View source for Medical ultrasound

{{About|imaging the human body|imaging of animals in research|Preclinical imaging|therapeutic use of ultrasound|Therapeutic ultrasound}}
{{hatnote|"Echography" and "Echograph" redirect here. Not to be confused with [[Echo sounding]].}}
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{{Use mdy dates|date=February 2023}}
{{Infobox interventions
| Name = Medical ultrasound
| Image = Sonographer doing pediatric echocardiography.JPG
| Caption = Sonographer carrying out [[echocardiography]] on a child
| ICD10 = B?4
| ICD9 = {{ICD9proc|88.7}}
| OPS301 = {{OPS301|3-03...3-05}}
| MeshID = D014463
| OtherCodes =
}}

'''Medical ultrasound''' includes [[Medical diagnosis|diagnostic techniques]] (mainly [[medical imaging|imaging]]) using [[ultrasound]], as well as [[therapeutic ultrasound|therapeutic]] applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as [[tendons]], [[muscles]], joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound. The usage of ultrasound to produce visual images for medicine is called '''medical ultrasonography''' or simply '''sonography'''. Sonography using ultrasound reflection is called '''echography'''. There are also transmission methods, such as [[ultrasound transmission tomography]]. The practice of examining [[pregnant]] women using ultrasound is called [[obstetric ultrasonography]], and was an early development of clinical ultrasonography. The machine used is called an '''ultrasound machine''', a '''sonograph''' or an '''echograph'''. The visual image formed using this technique is called an '''ultrasonogram''', a '''sonogram''' or an '''echogram'''.

[[File:Carotid ultrasound.jpg|thumb|[[Ultrasound]] of [[Common carotid artery|carotid artery]]]]
Ultrasound is composed of [[sound wave]]s with [[frequencies]] greater than 20,000&nbsp;[[Hz]], which is the approximate upper threshold of human hearing.<ref>{{cite journal |last1=Aldrich |first1=John E. |title=Basic physics of ultrasound imaging |journal=Critical Care Medicine |date=May 2007 |volume=35 |issue=Suppl |pages=S131–S137 |doi=10.1097/01.CCM.0000260624.99430.22|pmid=17446771 |s2cid=41843663 }}</ref> Ultrasonic images, also known as sonograms, are created by sending pulses of ultrasound into [[Tissue (biology)|tissue]] using a [[ultrasound transducer#Use in medicine|probe]]. The ultrasound [[echo|pulses echo]] off tissues with different reflection properties and are returned to the probe which records and displays them as an image.

A general-purpose [[ultrasonic transducer]] may be used for most imaging purposes but some situations may require the use of a specialized transducer. Most ultrasound examination is done using a transducer on the surface of the body, but improved visualization is often possible if a transducer can be placed inside the body. For this purpose, special-use transducers, including [[Transvaginal sonography|transvaginal]], endorectal, and [[Transesophageal echocardiogram|transesophageal]] transducers are commonly employed. At the extreme, very small transducers can be mounted on small diameter catheters and placed within blood vessels to image the walls and disease of those vessels.

==Types<span class="anchor" id="Modes"></span>==
The imaging mode refers to probe and machine settings that result in specific dimensions of the ultrasound image.<ref>{{cite book | vauthors=Postema M | title=Fundamentals of Medical Ultrasonics | doi=10.1201/9781482266641 | publisher=CRC Press | location=London | year=2011 | isbn=978-0-429-17648-7| url=https://hal.science/hal-03192439 }}</ref>
Several modes of ultrasound are used in medical imaging:<ref>The Gale Encyclopedia of Medicine, 2nd Edition, Vol. 1 A-B. p. 4</ref><ref name="Cobbold 422">{{cite book|author=Cobbold, Richard S. C. |title=Foundations of Biomedical Ultrasound|url=https://books.google.com/books?id=Hwb5D60vb5IC&pg=PA422|year=2007|publisher=Oxford University Press|isbn=978-0-19-516831-0|pages=422–423}}</ref>
* '''A-mode''': Amplitude mode refers to the mode in which the amplitude of the [[transducer]] voltage is recorded as a function of two-way travel time of an ultrasound pulse. A single pulse is transmitted through the body and scatters back to the same transducer element. The voltage amplitudes recorded correlate linearly to acoustic pressure amplitudes. A-mode is one-dimensional.
* '''B-mode''': In brightness mode, an array of transducer elements scans a plane through the body resulting in a two-dimensional image. Each pixel value of the image correlates to voltage amplitude registered from the backscattered signal. The dimensions of B-mode images are voltage as a function of angle and two-way time.
* '''M-mode''': In motion mode, A-mode pulses are emitted in succession. The backscattered signal is converted to lines of bright pixels, whose brightness linearly correlates to backscattered voltage amplitudes. Each next line is plotted adjacent to the previous, resulting in an image that looks like a B-mode image. The M-mode image dimensions are however voltage as a function of two-way time and recording time. This mode is an ultrasound analogy to streak [[video]] recording in high-speed photography. As moving tissue transitions produce backscattering, this can be used to determine the displacement of specific organ structures, most commonly the heart.

Most machines convert two-way time to imaging depth using as assumed speed of sound of 1540&nbsp;m/s. As the actual speed of sound varies greatly in different tissue types, an [[ultrasound]] image is therefore not a true tomographic representation of the body.<ref>{{cite book|vauthors=Postema M, Kotopoulis S, Jenderka KV|chapter=Physical principles of medical ultrasound|edition=2nd|publisher=EFSUMB|location=London|year=2019|pages=1–23|editor=Dietrich CF|title=EFSUMB Course Book|doi=10.37713/ECB01|s2cid=216415694 |url=https://hal.archives-ouvertes.fr/hal-03191256/file/2019EFSUMB2.pdf }}</ref>

Three-dimensional imaging is done by combining B-mode images, using dedicated rotating or stationary probes. This has also been referred to as '''C-mode'''.<ref name="Cobbold 422"/>

An imaging technique refers to a method of signal generation and processing that results in a specific application.
Most imaging techniques are operating in B-mode.
* '''[[Doppler sonography]]''': This imaging technique makes use of the [[Doppler effect]] in detection and measuring moving targets, typically blood.
* '''Harmonic imaging''': backscattered signal from tissue is filtered to comprise only frequency content of at least twice the centre frequency of the transmitted ultrasound. Harmonic imaging used for perfusion detection when using ultrasound [[contrast agents]] and for the detection of tissue harmonics. Common pulse schemes for the creation of harmonic response without the need of real-time [[Fourier analysis]] are pulse inversion and power modulation.<ref name="Starkoff 2014"/>

[[File:B-flow ultrasonography of venous reflux.jpg|thumb|B-flow image of [[chronic venous insufficiency|venous reflux]]. {{noprint|[[:File:B-flow ultrasonography of venous reflux.gif|Video is available]].}}]]
*'''B-flow''' is an imaging technique that digitally highlights moving reflectors (mainly [[red blood cell]]s) while suppressing the signals from the surrounding stationary tissue. It aims to visualize flowing blood and surrounding stationary tissues simultaneously.<ref name="WangChou2005">{{cite journal |last1=Wang |first1=Hsin-Kai |last2=Chou |first2=Yi-Hong |last3=Chiou |first3=Hong-Jen |last4=Chiou |first4=See-Ying |last5=Chang |first5=Cheng-Yen |title=B-flow Ultrasonography of Peripheral Vascular Diseases |journal=Journal of Medical Ultrasound |date=2005 |volume=13 |issue=4 |pages=186–195 |doi=10.1016/S0929-6441(09)60108-9 |doi-access=free }}</ref> It is thus an alternative or complement to [[Doppler ultrasonography]] in visualizing blood flow.<ref name="Wachsberg2007">{{cite journal |last1=Wachsberg |first1=Ronald H. |title=B-Flow Imaging of the Hepatic Vasculature: Correlation with Color Doppler Sonography |journal=American Journal of Roentgenology |date=June 2007 |volume=188 |issue=6 |pages=W522–W533 |doi=10.2214/AJR.06.1161 |pmid=17515342 }}</ref>

[[Therapeutic ultrasound]] aimed at a specific tumor or calculus is not an imaging mode. However, for positioning a treatment probe to focus on a specific region of interest, A-mode and B-mode are typically used, often during treatment.<ref>{{cite journal |last1=Tzou |first1=David T. |last2=Usawachintachit |first2=Manint |last3=Taguchi |first3=Kazumi |last4=Chi |first4=Thomas |title=Ultrasound Use in Urinary Stones: Adapting Old Technology for a Modern-Day Disease |journal=Journal of Endourology |date=April 2017 |volume=31 |issue=S1 |pages=S–89–S-94 |doi=10.1089/end.2016.0584|pmid=27733052 |pmc=5397246 }}</ref>

==Advantages and drawbacks==
{{Unreferenced section|date=May 2025}}
Compared to other medical imaging modalities, ultrasound has several advantages. It provides images in real-time,<ref>{{cite book |last1=Van Woudenberg |first1=Nathan |last2=Liao |first2=Zhibin |last3=Abdi |first3=Amir H. |last4=Girgis |first4=Hani |last5=Luong |first5=Christina |last6=Vaseli |first6=Hooman |last7=Behnami |first7=Delaram |last8=Zhang |first8=Haotian |last9=Gin |first9=Kenneth |last10=Rohling |first10=Robert |last11=Tsang |first11=Teresa |last12=Abolmaesumi |first12=Purang |title=Simulation, Image Processing, and Ultrasound Systems for Assisted Diagnosis and Navigation |chapter=Quantitative Echocardiography: Real-Time Quality Estimation and View Classification Implemented on a Mobile Android Device |series=Lecture Notes in Computer Science |date=2018 |volume=11042 |pages=74–81 |doi=10.1007/978-3-030-01045-4_9 |isbn=978-3-030-01044-7 }}</ref> is [[Portable ultrasound|portable]], and can consequently be brought to the bedside. It is substantially lower in cost than other imaging strategies. Drawbacks include various limits on its field of view, the need for patient cooperation, dependence on patient physique, difficulty imaging structures obscured by [[bone]], air or gases,<ref group="note">It is for this reason that the person subjected to ultrasound of organs that can contain quantities of air or gas, such as the stomach, intestine and bladder, must follow a food preparation designed to reduce their quantity: specific diet and supplements for the intestine and intake of non-carbonated water to fill the bladder; sometimes, during the examination, it may be required to fill the stomach with non-carbonated water.</ref> and the necessity of a skilled operator, usually with professional training.

==Uses==
[[File:UltrasoundBPH.jpg|thumb|[[Urinary bladder]] (black butterfly-like shape) and hyperplastic [[prostate]] (BPH) visualized by medical ultrasound]]
Sonography (ultrasonography) is widely used in [[medicine]]. It is possible to perform both [[medical diagnosis|diagnosis]] and [[Therapeutic ultrasound|therapeutic procedures]], using [[ultrasound]] to guide interventional procedures such as [[biopsies]] or to drain collections of fluid, which can be both diagnostic and therapeutic. [[Sonographer]]s are medical professionals who perform scans which are traditionally interpreted by radiologists, physicians who specialize in the application and interpretation of medical imaging modalities, or by cardiologists in the case of cardiac ultrasonography ([[echocardiography]]). Sonography is effective for imaging soft tissues of the body.<ref>{{cite journal |last1=Izadifar |first1=Zahra |last2=Babyn |first2=Paul |last3=Chapman |first3=Dean |title=Mechanical and Biological Effects of Ultrasound: A Review of Present Knowledge |journal=Ultrasound in Medicine & Biology |date=June 2017 |volume=43 |issue=6 |pages=1085–1104 |doi=10.1016/j.ultrasmedbio.2017.01.023|pmid=28342566 |s2cid=3687095 |doi-access=free }}</ref> Superficial structures such as [[muscle]], [[tendon]], [[testis]], [[breast]], [[thyroid]] and parathyroid glands, and the [[neonatal]] brain are imaged at higher [[frequencies]] (7–18&nbsp;MHz), which provide better linear (axial) and horizontal (lateral) [[Angular resolution|resolution]]. Deeper structures such as liver and kidney are imaged at lower frequencies (1–6&nbsp;MHz) with lower axial and lateral resolution as a price of deeper tissue penetration.{{citation needed|date=July 2024}}

=== Anesthesiology ===
In [[anesthesiology]], ultrasound is commonly used to guide the placement of needles when injecting local anesthetic solutions in the proximity of [[nerve]]s identified within the ultrasound image (nerve block). It is also used for vascular access such as [[cannulation]] of large central veins and for difficult [[arterial cannulation]]. [[Transcranial Doppler]] is frequently used by neuro-anesthesiologists for obtaining information about flow-velocity in the basal [[Cerebral circulation|cerebral vessels]].{{citation needed|date=April 2022}}

=== Angiology (vascular) ===
[[Image:IVUS of CAD (1).png|right|thumb|Intravascular ultrasound image of a coronary artery (left), with color-coding on the right, delineating the lumen (yellow), external elastic membrane (blue) and the atherosclerotic plaque burden (green)]]
{{Further|Doppler ultrasonography|Intravascular ultrasound}}
In [[angiology]] or [[Blood vessel|vascular]] medicine, [[duplex ultrasound]]  (B Mode imaging combined with Doppler flow measurement) is used to diagnose arterial and venous disease. This is particularly important in [[neurology|potential neurologic problems]], where [[Carotid ultrasonography|carotid ultrasound]] is commonly used for assessing blood flow and potential or suspected stenosis in the [[carotid artery|carotid arteries]], while [[transcranial Doppler]] is used for imaging flow in the intracerebral arteries.{{citation needed|date=April 2022}}

[[Intravascular ultrasound]] (''IVUS'') uses a specially designed [[catheter]] with a miniaturized [[ultrasound]] probe attached to its distal end, which is then threaded inside a blood vessel. The proximal end of the [[catheter]] is attached to computerized [[ultrasound]] equipment and allows the application of [[ultrasound]] technology, such as a [[piezoelectric transducer]] or [[capacitive micromachined ultrasonic transducer]], to visualize the [[endothelium]] of [[blood vessel]]s in living individuals.<ref name="pmid21327914">{{cite journal | vauthors = Garcìa-Garcìa HM, Gogas BD, Serruys PW, Bruining N | title = IVUS-based imaging modalities for tissue characterization: similarities and differences | journal = Int J Cardiovasc Imaging | volume = 27 | issue = 2 | pages = 215–24 | date = February 2011 | pmid = 21327914 | pmc = 3078312 | doi = 10.1007/s10554-010-9789-7 }}</ref>

In the case of the common and potentially, serious problem of blood clots in the deep veins of the leg, [[ultrasonography of deep venous thrombosis|ultrasound]] plays a key diagnostic role, while [[ultrasonography of chronic venous insufficiency of the legs]] focuses on more [[superficial vein]]s to assist with planning of suitable interventions to relieve symptoms or improve cosmetics.{{citation needed|date=August 2022}}

=== Cardiology (heart) ===
{{Main|Echocardiography}}
[[File:Ultrasound of human heart apical 4-cahmber view.gif|thumb|Ultrasound of human [[heart]] showing the four chambers and mitral and [[tricuspid]] valves]]

[[Echocardiography]] is an essential tool in [[cardiology]], assisting in evaluation of [[heart valve]] function, such as [[Mitral valve stenosis|stenosis]] or [[Aortic valve insufficiency|insufficiency]], strength of [[cardiac muscle]] contraction, and [[Ventricular hypertrophy|hypertrophy]] or [[Ventricular dilation|dilatation]] of the main chambers. ([[Ventricle (heart)|ventricle]] and [[Atrium (heart)|atrium]]){{citation needed|date=April 2022}}

=== Emergency medicine ===
{{Main|Emergency ultrasound}}
[[Point-of-care ultrasound|Point of care]] ultrasound has many applications in [[emergency medicine]].<ref>{{cite journal |title=Ultrasound Guidelines: Emergency, Point-of-Care and Clinical Ultrasound Guidelines in Medicine |journal=Annals of Emergency Medicine |date=May 2017 |volume=69 |issue=5 |pages=e27–e54 |doi=10.1016/j.annemergmed.2016.08.457|pmid=28442101 |s2cid=42739523 }}</ref> These include differentiating cardiac from pulmonary causes of [[Pulmonary edema|acute breathlessness]], and the [[Focused assessment with sonography for trauma|Focused Assessment with Sonography for Trauma (FAST) exam]], extended to include assessment for significant [[hemoperitoneum]] or [[pericardial tamponade]] after [[Physical trauma|trauma]] ([[EFAST]]). Other uses include assisting with differentiating causes of abdominal pain such as [[gallstone]]s and [[kidney stones]]. Emergency Medicine Residency Programs have a substantial history of promoting the use of bedside ultrasound during physician training.{{citation needed|date=August 2022}}

=== Gastroenterology/Colorectal surgery ===
{{Further|Abdominal ultrasonography|Endoanal ultrasound}}

Both [[abdominal ultrasonography|abdominal]] and [[endoanal ultrasound]] are frequently used in [[gastroenterology]] and [[colorectal surgery]]. In abdominal sonography, the major organs of the abdomen such as the [[pancreas]], [[aorta]], [[inferior vena cava]], [[liver]], [[gall bladder]], [[bile duct]]s, [[kidney]]s, and [[spleen]] may be imaged. However, sound waves may be blocked by gas in the [[bowel]] and attenuated to differing degrees by fat, sometimes limiting diagnostic capabilities. The [[Vermiform appendix|appendix]] can sometimes be seen when inflamed (e.g.: [[appendicitis]]) and ultrasound is the initial imaging choice, avoiding radiation if possible, although it frequently needs to be followed by other imaging methods such as [[computerised tomography|CT]]. [[Endoanal ultrasound]] is used particularly in the investigation of anorectal symptoms such as [[fecal incontinence]] or [[obstructed defecation]].{{citation needed|date=July 2021}} It images the immediate [[perianal]] anatomy and is able to detect occult defects such as tearing of the [[Anal sphincterotomy|anal sphincter]].

=== Hepatology ===

[[Ultrasonography of liver tumors]] allows for both detection and characterization.<ref>{{cite journal |last1=Harvey |first1=Christopher J. |last2=Albrecht |first2=Thomas |title=Ultrasound of focal liver lesions |journal=European Radiology |date=September 2001 |volume=11 |issue=9 |pages=1578–1593 |doi=10.1007/s003300101002|pmid=11511877 |s2cid=20513478 }}</ref>
Ultrasound imaging studies are often obtained during the evaluation process of [[Fatty liver disease]]. Ultrasonography reveals a "bright" liver with increased echogenicity. Pocket-sized ultrasound devices might be used as point-of-care screening tools to diagnose liver steatosis.<ref>{{cite journal | last1=Miles | first1=D. A. | last2=Levi | first2=C. S. | last3=Uhanova | first3=J. | last4=Cuvelier | first4=S. | last5=Hawkins | first5=K. | last6=Minuk | first6=G. Y. | title=Pocket-Sized Versus Conventional Ultrasound for Detecting Fatty Infiltration of the Liver | journal=Digestive Diseases and Sciences | date=2020 | volume=65 | issue=1 | pages=82–85 | doi=10.1007/s10620-019-05752-x | pmid=31376083 }}</ref><ref>{{cite journal | last1=Costantino | first1=Andrea | last2=Piagnani | first2=Alessandra | last3=Caccia | first3=Riccardo | last4=Sorge | first4=Andrea | last5=Maggioni | first5=Marco | last6=Perbellini | first6=Riccardo | last7=Donato | first7=Francesca | last8=d'Ambrosio | first8=Roberta | last9=Sed | first9=Nicole Piazza O. | last10=Valenti | first10=Luca | last11=Prati | first11=Daniele | last12=Vecchi | first12=Maurizio | last13=Lampertico | first13=Pietro | last14=Fraquelli | first14=Mirella | title=Reproducibility and accuracy of a pocket-size ultrasound device in assessing liver steatosis | journal=Digestive and Liver Disease | date=2024 | volume=56 | issue=6 | pages=1032–1038 | doi=10.1016/j.dld.2023.11.014 | pmid=38016894 }}</ref>

=== Gynecology and obstetrics ===
{{Main|Gynecologic ultrasonography|Obstetric ultrasonography}}

[[File:Head-3D.jpg|thumb|right|Orthogonal planes of a three-dimensional sonographic volume with transverse and coronal measurements for estimating fetal cranial volume<ref>{{cite journal |doi=10.1177/875647938500100504 |title=Fetal Biometry: Vertical Calvarial Diameter and Calvarial Volume |year=1985 |last1=Dubose |first1=T. J. |journal=[[Journal of Diagnostic Medical Sonography]] |volume=1 |issue=5 |pages=205–217|s2cid=73129628 }}</ref><ref>{{cite web|url=http://hcp.obgyn.net/ultrasound/content/article/1760982/1906113|title=3D BPD Correction|last=Dubose|first=Terry|date=July 14, 2011|archive-url=https://web.archive.org/web/20160303035029/http://www.obgyn.net/articles/3d-bpd-correction|archive-date=March 3, 2016|access-date=2015-01-14}}</ref>]]
[[Gynecologic ultrasonography]] examines female pelvic organs (specifically the [[uterus]], [[ovaries]], and [[fallopian tubes]]) as well as the [[bladder]], [[Adnexa of uterus|adnexa]], and [[pouch of Douglas]]. It uses transducers designed for approaches through the lower abdominal wall, curvilinear and sector, and specialty transducers such as [[transvaginal ultrasound]].<ref>{{Cite web |url=https://www.bmus.org/for-patients/what-to-expect-from-different-types-of-ultrasound-examination/pelvic-gynaecology-ultrasound-including-transvaginal/ |title=Pelvic / Gynaecology Ultrasound (including transvaginal) |access-date=2023-12-20 |website=The British Medical Ultrasound Society}}</ref>

[[Obstetrical ultrasonography|Obstetrical sonography]] was originally developed in the late 1950s and 1960s by Sir [[Ian Donald]]<ref>{{cite journal |last1=Hellman |first1=LouisM. |last2=Duffus |first2=GillianM. |last3=Donald |first3=Ian |last4=Sundén |first4=Bertil |title=Safety of Diagnostic Ultrasound in Obstetrics |journal=The Lancet |date=May 1970 |volume=295 |issue=7657 |pages=1133–1135 |doi=10.1016/s0140-6736(70)91212-2|pmid=4192094 }}</ref><ref>{{cite journal |last1=Campbell |first1=S |title=A short history of sonography in obstetrics and gynaecology. |journal=Facts, Views & Vision in ObGyn |date=2013 |volume=5 |issue=3 |pages=213–29 |pmid=24753947|pmc=3987368 }}</ref> and is commonly used during [[pregnancy]] to check the development and presentation of the [[fetus]]. It can be used to identify many conditions that could be potentially harmful to the mother and/or baby possibly remaining undiagnosed or with delayed diagnosis in the absence of sonography. It is currently believed that the risk of delayed diagnosis is greater than the small risk, if any, associated with undergoing an ultrasound scan. However, its use for non-medical purposes such as fetal "keepsake" videos and photos is discouraged.<ref name="keepsake">{{cite web|url=https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm095508.htm|title=Avoid Fetal "Keepsake" Images, Heartbeat Monitors|website=U.S. food and Drug Administration|publisher=U.S. Government|archive-url=https://web.archive.org/web/20190423055443/https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm095508.htm|archive-date=April 23, 2019|access-date=11 September 2017}}</ref>

Obstetric ultrasound is primarily used to:{{citation needed|date=July 2024}}
* Date the pregnancy ([[gestational age]])
* Confirm fetal viability
* Determine location of [[fetus]], intrauterine vs [[Ectopic pregnancy|ectopic]]
* Check the location of the placenta in relation to the cervix
* Check for the number of fetuses ([[multiple pregnancy]])
* Check for major physical abnormalities.
* Assess fetal growth (for evidence of [[intrauterine growth restriction]] (IUGR))
* Check for fetal movement and heartbeat.
* Determine the sex of the baby

According to the European Committee of Medical Ultrasound Safety (ECMUS)<ref>[http://www.efsumb.org/ecmus/ecmus-ss-uk.asp Clinical Safety Statements] {{webarchive|url=https://web.archive.org/web/20120626122956/http://www.efsumb.org/ecmus/ecmus-ss-uk.asp |date=2012-06-26 }}. Efsumb.org. Retrieved on 2011-11-13.</ref>
{{blockquote|Ultrasonic examinations should only be performed by competent personnel who are trained and updated in safety matters. Ultrasound produces heating, pressure changes and mechanical disturbances in tissue. Diagnostic levels of ultrasound can produce temperature rises that are hazardous to sensitive organs and the embryo/fetus. Biological effects of non-thermal origin have been reported in animals but, to date, no such effects have been demonstrated in humans, except when a micro-bubble [[contrast agent]] is present.}}Nonetheless, care should be taken to use low power settings and avoid pulsed wave scanning of the fetal brain unless specifically indicated in high risk pregnancies.{{citation needed|date=August 2022}}

Figures released for the period 2005–2006 by the UK Government (Department of Health) show that non-obstetric ultrasound examinations constituted more than 65% of the total number of ultrasound scans conducted.

=== Hemodynamics (blood circulation) ===
Blood velocity can be measured in various blood vessels, such as [[middle cerebral artery]] or [[descending aorta]], by relatively inexpensive and low risk ultrasound Doppler probes attached to portable monitors.<ref>{{Cite web | url=https://www.uscom.com.au/products/uscom1a/applications/ |title = Applications » Uscom}}</ref> These provide non-invasive or transcutaneous (non-piercing) minimal invasive blood flow assessment. Common examples are [[transcranial Doppler]], [[Esophogeal doppler|esophageal Doppler]] and [[Transthoracic echocardiogram|suprasternal Doppler]].{{citation needed|date=April 2022}}

=== Otolaryngology (head and neck) ===
{{Anchor|Head ultrasonography|Neck ultrasonography|Thyroid ultrasonography}}
[[File:Neck ultrasound.jpg|thumb|Neck ultrasound]]
Most structures of the neck, including the [[thyroid]] and [[parathyroid gland]]s,<ref>Ghervan C. Thyroid and parathyroid ultrasound. Med Ultrason. 2011 Mar;13(1):80-4. PMID 21390348.</ref> [[lymph nodes]], and [[salivary glands]], are well-visualized by high-frequency ultrasound with exceptional anatomic detail. Ultrasound is the preferred imaging modality for thyroid tumors and lesions, and its use is important in the evaluation, preoperative planning, and postoperative surveillance of patients with [[thyroid cancer]]. Many other benign and malignant conditions in the head and neck can be differentiated, evaluated, and managed with the help of diagnostic ultrasound and ultrasound-guided procedures.{{citation needed|date=August 2022}}

=== Neonatology ===
In [[neonatology]], [[transcranial Doppler]] can be used for basic assessment of intracerebral structural abnormalities, suspected hemorrhage, [[ventriculomegaly]] or [[hydrocephalus]] and anoxic insults ([[periventricular leukomalacia]]). It can be performed through the soft spots in the skull of a newborn infant ([[Fontanelle]]) until these completely close at about 1 year of age by which time they have formed a virtually impenetrable acoustic barrier to ultrasound.<ref>{{cite journal |last1=Yoshida |first1=Hiroko |last2=Yasuhara |first2=Akihiro |last3=Kobayashi |first3=Yohnosuke |title=Transcranial Doppler sonographic studies of cerebral blood flow velocity in neonates |journal=Pediatric Neurology |date=March 1991 |volume=7 |issue=2 |pages=105–110 |doi=10.1016/0887-8994(91)90005-6|pmid=2059249 }}</ref> The most common site for [[cranial ultrasound]] is the anterior fontanelle. The smaller the fontanelle, the more the image is compromised.{{citation needed|date=July 2024}}

Lung ultrasound has been found to be useful in diagnosing common neonatal respiratory diseases such as transient tachypnea of the newborn, respiratory distress syndrome, congenital pneumonia, meconium aspiration syndrome, and pneumothorax.<ref>{{Cite journal |last1=Singh |first1=Yogen |last2=Tissot |first2=Cecile |last3=Fraga |first3=María V. |last4=Yousef |first4=Nadya |last5=Cortes |first5=Rafael Gonzalez |last6=Lopez |first6=Jorge |last7=Sanchez-de-Toledo |first7=Joan |last8=Brierley |first8=Joe |last9=Colunga |first9=Juan Mayordomo |last10=Raffaj |first10=Dusan |last11=Da Cruz |first11=Eduardo |last12=Durand |first12=Philippe |last13=Kenderessy |first13=Peter |last14=Lang |first14=Hans-Joerg |last15=Nishisaki |first15=Akira |date=2020-02-24 |title=International evidence-based guidelines on Point of Care Ultrasound (POCUS) for critically ill neonates and children issued by the POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC) |journal=Critical Care |volume=24 |issue=1 |page=65 |doi=10.1186/s13054-020-2787-9 |doi-access=free |issn=1466-609X |pmc=7041196 |pmid=32093763}}</ref> A neonatal lung ultrasound score, first described by Brat et al., has been found to highly correlate with oxygenation in the newborn.<ref>{{Cite journal |last1=Brat |first1=Roselyne |last2=Yousef |first2=Nadya |last3=Klifa |first3=Roman |last4=Reynaud |first4=Stephanie |last5=Shankar Aguilera |first5=Shivani |last6=De Luca |first6=Daniele |date=August 2015 |title=Lung Ultrasonography Score to Evaluate Oxygenation and Surfactant Need in Neonates Treated With Continuous Positive Airway Pressure |journal=JAMA Pediatrics |volume=169 |issue=8 |pages=e151797 |doi=10.1001/jamapediatrics.2015.1797 |issn=2168-6211 |pmid=26237465}}</ref><ref>{{Cite journal |last1=Kelner |first1=Jacob |last2=Moote |first2=Douglas |last3=Shah |first3=Rahul |last4=Anuar |first4=Amirul |last5=Golioto |first5=Annmarie |date=2024-08-09 |title=Lung Ultrasound Score for Prediction of Surfactant Administration in Preterm Infants with Respiratory Failure |journal=Journal of Perinatology|volume=44 |issue=9 |pages=1258–1263 |doi=10.1038/s41372-024-02090-3 |issn=1476-5543 |pmid=39122885}}</ref>

=== Ophthalmology ({{visible anchor|eyes}}) ===
In [[ophthalmology]] and [[optometry]], there are two major forms of eye exam using ultrasound:
* [[A-scan ultrasound biometry]], is commonly referred to as an ''A-scan'' (''amplitude scan''). [[#Modes|A-mode]] provides data on the length of the [[human eye|eye]], which is a major determinant in [[eye disease|common sight disorders]], especially for determining the power of an intraocular lens after cataract extraction.{{citation needed|date=April 2022}}
* ''B-scan ultrasonography'', or ''B-scan-Brightness scan'', is a [[#Modes|B-mode]] scan that produces a cross-sectional view of the [[human eye|eye]] and the [[orbit (anatomy)|orbit]]. It is an essential tool in ophthalmology for diagnosing and managing a wide array of conditions affecting the posterior segment of the eye.It is non invasive and uses frequency 10–15&nbsp;MHz. It is often used in conjunction with other imaging techniques (like OCT or fluorescein angiography) for a more comprehensive evaluation of ocular conditions.

=== {{anchor|Pulmonology (lungs)}}Pulmonology (lungs) ===
Ultrasound is used to assess the [[lung]]s in a variety of settings including critical care, emergency medicine, trauma surgery, as well as general medicine and nursing. This imaging modality is used at the bedside or examination table to evaluate a number of different lung abnormalities as to guide [[respiratory therapy]] and [[mechanical ventilation]], and procedures such as [[thoracentesis]], (drainage of pleural fluid (effusion)), needle aspiration biopsy, and [[catheter]] placement.<ref>{{Cite web|url=https://www.uptodate.com/contents/bedside-pleural-ultrasonography-equipment-technique-and-the-identification-of-pleural-effusion-and-pneumothorax|title=UpToDate|website=www.uptodate.com|access-date=2019-07-23}}</ref> Although air present in the lungs does not allow good penetration of ultrasound waves, interpretation of specific artifacts created on the lung surface can be used to detect abnormalities.<ref>{{Cite web|url=https://lus.mstech.eu|title=Lung Ultrasound Simulator|access-date=2021-09-30}}</ref>

Lung, or pulmonary ultrasound does not visualise the lung itself, but the tissue-air-interface at the pleural line. The fact that artefact interpretation is essential sets lung ultrasound apart from modalities aimed at imaging an actual organ. This distinction has mechanical implications that are important when trying to interpret artifactual patterns. Where modern sonography is aided by software filters and acoustic harmonics to enhance visualisation of organs such as the heart or liver, they corrupt the specific patterns sought in lung ultrasound. Therefore, a software preset void of imaging filters, harmonic imaging, and beam compounding, is preferred.<ref>{{Cite journal|title=New International Guidelines and Consensus on the Use of Lung Ultrasound|journal=Journal of Ultrasound in Medicine |date=2023 |volume=42 |issue=2 |pages=309–344 |doi=10.1002/jum.16088 |pmid=35993596 |pmc=10086956 | vauthors = Demi L, Wolfram F, Klersy C, De Silvestri A, Ferretti VV, Muller M, Miller D, Feletti F, Wełnicki M, Buda N, Skoczylas A, Pomiecko A, Damjanovic D, Olszewski R, Kirkpatrick AW, Breitkreutz R, Mathis G, Soldati G, Smargiassi A, Inchingolo R, Perrone T }}</ref>

==== Lung ultrasound basics ====
* '''The Normal Lung Surface:''' The lung surface is composed of visceral and parietal [[pleura]]. These two surfaces are typically pushed together and make up the pleural line, which is the basis of lung (or pleural) ultrasound. This line is visible less than a centimeter below the rib line in most adults. On ultrasound, it is visualized as a [[hyperechoic]] (bright white) horizontal line if the ultrasound probe is applied perpendicularly to the skin.
* '''Artifacts:''' Lung ultrasound relies on artifacts, which would otherwise be considered a hindrance in imaging. Air blocks the ultrasound beam and thus visualizing healthy lung tissue itself with this mode of imaging is not practical. Consequently, physicians and sonographers have learned to recognize patterns that ultrasound beams create when imaging healthy versus diseased lung tissue. Three commonly seen and utilized artifacts in lung ultrasound include lung sliding, A-lines, and B-lines.<ref name=":0">{{Cite book|title=Lung Ultrasound in the Critically Ill: The BLUE Protocol|last=Lichtenstein|first=Daniel|publisher=Springer|year=2016|isbn=978-3-319-15370-4}}</ref>
** §&nbsp; '''Lung Sliding:''' The presence of lung sliding, which indicates the shimmering of the pleural line that occurs with movement of the visceral and parietal pleura against one another with respiration (sometimes described as 'ants marching'), is the most important finding in normal aerated lung.<ref name=":1">{{cite journal |last1=Husain |first1=LubnaF |last2=Hagopian |first2=Laura |last3=Wayman |first3=Derek |last4=Baker |first4=WilliamE |last5=Carmody |first5=KristinA |title=Sonographic diagnosis of pneumothorax |journal=Journal of Emergencies, Trauma, and Shock |date=2012 |volume=5 |issue=1 |pages=76–81 |doi=10.4103/0974-2700.93116 |pmid=22416161 |pmc=3299161 |doi-access=free }}</ref> Lung sliding indicates both that the lung is present at the chest wall and that the lung is functioning.<ref name=":0" />
** §&nbsp; '''A-lines:''' When the ultrasound beam makes contact with the [[Pulmonary pleurae|pleural line]], it is reflected back creating a bright white horizontal line. The subsequent reverberation artifacts that appear as equally spaced horizontal lines deep to the pleura are A-lines. Ultimately, A-lines are a reflection of the ultrasound beam from the pleura with the space between A-lines corresponding to the distance between the parietal pleura and the skin surface.<ref name=":0" /> A-lines indicate the presence of air, which means that these artifacts can be present in normal healthy lung (and also in patients with pneumothorax).<ref name=":1" />
** §&nbsp; '''B-lines:''' B-lines are also reverberation artifacts. They are visualized as [[hyperechoic]] vertical lines extending from the pleura to the edge of the ultrasound screen. These lines are sharply defined and laser-like and typically do not fade as they progress down the screen.<ref name=":0" /> A few B-lines that move along with the sliding pleura can be seen in normal lung due to acoustic impedance differences between water and air. However, excessive B-lines (three or more) are abnormal and are typically indicative of underlying lung pathology.<ref name=":1" />

==== Lung pathology assessed with ultrasound ====
* '''[[Pulmonary edema]]''': Lung ultrasound has been shown to be very sensitive for the detection of pulmonary edema. It allows for improvement in diagnosis and management of critically ill patients, particularly when used in combination with echocardiography. The sonographic feature that is present in pulmonary edema is multiple B-lines. B-lines can occur in a healthy lung; however, the presence of 3 or more in the anterior or lateral lung regions is always abnormal. In pulmonary edema, B-lines indicate an increase in the amount of water contained in the lungs outside of the pulmonary vasculature. B-lines can also be present in a number of other conditions including pneumonia, pulmonary contusion, and lung infarction.<ref>{{Cite journal|last1=Blanco|first1=Pablo A.|last2=Cianciulli|first2=Tomás F.|date=2016|title=Pulmonary Edema Assessed by Ultrasound: Impact in Cardiology and Intensive Care Practice|journal=Echocardiography|language=en|volume=33|issue=5|pages=778–787|doi=10.1111/echo.13182|pmid=26841270|s2cid=37476194}}</ref> Additionally, it is important to note that there are multiple types of interactions between the pleural surface and the ultrasound wave that can generate artifacts with some similarity to B-lines but which do not have pathologic significance.<ref>{{cite journal |last1=Soldati |first1=Gino |last2=Demi |first2=Marcello |title=The use of lung ultrasound images for the differential diagnosis of pulmonary and cardiac interstitial pathology |journal=Journal of Ultrasound |date=June 2017 |volume=20 |issue=2 |pages=91–96 |doi=10.1007/s40477-017-0244-7 |pmid=28592998 |pmc=5440336 }}</ref>
* '''[[Atelectasis]]''': Consolidations are, as opposed to artifactual patterns, directly visualised on lung ultrasound. Differentiation of consolidations within the lung can be made with qualitative methods such as the presence of dynamic, or static air bronchograms, being air trapped within smaller airways inside of consolidations. Pathognomic changes in resorptive and [[compressive atelectasis]], respectively can thus be distinguished. 
* '''[[Pneumothorax]]''': In clinical settings when pneumothorax is suspected, lung ultrasound can aid in diagnosis.<ref>{{cite journal |last1=Volpicelli |first1=Giovanni |last2=Elbarbary |first2=Mahmoud |last3=Blaivas |first3=Michael |last4=Lichtenstein |first4=Daniel A. |last5=Mathis |first5=Gebhard |last6=Kirkpatrick |first6=Andrew W. |last7=Melniker |first7=Lawrence |last8=Gargani |first8=Luna |last9=Noble |first9=Vicki E. |last10=Via |first10=Gabriele |last11=Dean |first11=Anthony |last12=Tsung |first12=James W. |last13=Soldati |first13=Gino |last14=Copetti |first14=Roberto |last15=Bouhemad |first15=Belaid |last16=Reissig |first16=Angelika |last17=Agricola |first17=Eustachio |last18=Rouby |first18=Jean-Jacques |last19=Arbelot |first19=Charlotte |last20=Liteplo |first20=Andrew |last21=Sargsyan |first21=Ashot |last22=Silva |first22=Fernando |last23=Hoppmann |first23=Richard |last24=Breitkreutz |first24=Raoul |last25=Seibel |first25=Armin |last26=Neri |first26=Luca |last27=Storti |first27=Enrico |last28=Petrovic |first28=Tomislav |title=International evidence-based recommendations for point-of-care lung ultrasound |journal=Intensive Care Medicine |date=April 2012 |volume=38 |issue=4 |pages=577–591 |doi=10.1007/s00134-012-2513-4 |pmid=22392031 |doi-access=free }}</ref> In pneumothorax, air is present between the two layers of the pleura and lung sliding on ultrasound is therefore absent. The [[negative predictive value]] for lung sliding on ultrasound is reported as 99.2–100%&nbsp;– briefly, if lung sliding is present, a pneumothorax is effectively ruled out.<ref name=":1" /> The absence of lung sliding, however, is not necessarily specific for pneumothorax as there are other conditions that also cause this finding including [[acute respiratory distress syndrome]], [[Pulmonary consolidation|lung consolidations]], pleural adhesions, and [[pulmonary fibrosis]].<ref name=":1" />
* '''[[Pleural effusion]]''': Lung ultrasound is a cost-effective, safe, and non-invasive imaging method that can aid in the prompt visualization and diagnosis of pleural effusions. Effusions can be diagnosed by a combination of physical exam, percussion, and [[auscultation]] of the chest. However, these exam techniques can be complicated by a variety of factors including the presence of [[mechanical ventilation]], obesity, or patient positioning, all of which reduce the sensitivity of the physical exam. Consequently, lung ultrasound can be an additional tool to augment plain [[Chest radiograph|chest Xray]] and [[CT scan|chest CT]].<ref name=":2">{{cite journal |last1=Brogi |first1=E. |last2=Gargani |first2=L. |last3=Bignami |first3=E. |last4=Barbariol |first4=F. |last5=Marra |first5=A. |last6=Forfori |first6=F. |last7=Vetrugno |first7=L. |title=Thoracic ultrasound for pleural effusion in the intensive care unit: a narrative review from diagnosis to treatment |journal=Critical Care |date=December 2017 |volume=21 |issue=1 |page=325 |doi=10.1186/s13054-017-1897-5 |pmid=29282107 |pmc=5745967 |doi-access=free }}</ref> Pleural effusions on ultrasound appear as structural images within the thorax rather than an artifact. They will typically have four distinct borders including the pleural line, two rib shadows, and a deep border.<ref name=":0" /> In critically ill patients with pleural effusion, ultrasound may guide procedures including needle insertion, [[thoracentesis]], and [[Chest tube|chest-tube insertion]].<ref name=":2" />
* '''[[Lung cancer]] staging:''' In [[pulmonology]], endobronchial ultrasound (EBUS) probes are applied to standard flexible endoscopic probes and used by pulmonologists to allow for direct visualization of endobronchial lesions and lymph nodes prior to transbronchial needle aspiration.  Among its many uses, EBUS aids in lung cancer staging by allowing for lymph node sampling without the need for major surgery.<ref>{{cite journal |doi=10.1136/thx.2005.047829 |title=Real-time endobronchial ultrasound guided transbronchial needle aspiration for sampling mediastinal lymph nodes |year=2006 |last1=Herth |first1=F J F |last2=Eberhardt |first2=R |last3=Vilmann |first3=P |last4=Krasnik |first4=M |last5=Ernst |first5=A |journal=Thorax |volume=61 |issue=9 |pages=795–8 |pmid=16738038 |pmc=2117082}}</ref>
* '''[[COVID-19]]''': Lung ultrasound has proved useful in the diagnosis of COVID-19 especially in cases where other investigations are not available.<ref>{{cite journal |last1=Lesser |first1=FD |last2=Smallwood |first2=N |last3=Dachsel |first3=M |title=Point-of-care lung ultrasound during and after the COVID-19 pandemic |journal=Ultrasound |date=1 August 2021 |volume=29 |issue=3 |page=140 |pmid=34567225|  doi=10.1177/1742271X211033737| pmc=8366220 |s2cid=236980540 |doi-access=free }}</ref><ref>{{cite journal |last1=Knight |first1=T. |last2=Parulekar |first2=P. |last3=Rudge |first3=G. |last4=Lesser |first4=F. |last5=Dachsel |first5=M. |last6=Aujayeb |first6=A. |last7=Lasserson |first7=D. |last8=Smallwood |first8=N. |title=S68 National COVID point of care lung ultrasound evaluation (society for acute medicine with the intensive care society) |journal=Thorax |date=1 November 2021 |volume=76 |issue=Suppl 2 |pages=A44–A45 |doi=10.1136/thorax-2021-BTSabstracts.74|s2cid=243885812 |doi-access=free }}</ref><ref>{{cite journal |last1=Lesser |first1=FD |last2=Dachsel |first2=M |last3=Smallwood |first3=N |title=The Diagnostic Accuracy and Prognostic Value of Lung ultrasound in Suspected COVID-19 a retrospective service evaluation. |journal=Acute Medicine |date=2022 |volume=21 |issue=1 |pages=56–58 |doi=10.52964/AMJA.0895 |pmid=35342913|s2cid=247762623 |doi-access=free }}</ref>

=== Urinary tract ===
{{main|Urinary tract ultrasound}}
[[File:UltrasoundBPH.jpg|thumb|right|[[Urinary bladder]] (black butterfly-like shape) and hyperplastic [[prostate]] ([[Benign prostatic hyperplasia|BPH]]) visualized by medical sonographic technique]]

Ultrasound is routinely used in [[urology]] to determine the amount of fluid retained in a patient's bladder. In a pelvic sonogram, images include the [[uterus]] and [[ovaries]] or [[urinary bladder]] in females. In males, a sonogram will provide information about the bladder, [[prostate]], or [[testicles]] (for example to urgently distinguish [[epididymitis]] from [[testicular torsion]]). In young males, it is used to distinguish more benign testicular masses ([[varicocele]] or [[hydrocele]]) from [[testicular cancer]], which is curable but must be treated to preserve health and fertility. There are two methods of performing pelvic sonography – externally or internally. The internal pelvic sonogram is performed either trans[[vagina]]lly (in a woman) or transrectally (in a man). Sonographic imaging of the pelvic floor can produce important diagnostic information regarding the precise relationship of abnormal structures with other pelvic organs and it represents a useful hint to treat patients with symptoms related to pelvic prolapse, double incontinence and obstructed defecation.{{Citation needed|date=July 2021}} It is also used to diagnose and, at higher frequencies, to treat (break up) kidney stones or kidney crystals ([[nephrolithiasis]]).<ref>{{cite journal |url=http://www.pelviperineology.org/practical/sonography_female_pelvic_floor_clinical_indications_and_techniques.html |title=Sonography of the female pelvic floor:clinical indications and techniques |first1=Vittorio Luigi |last1=Piloni |first2=Liana |last2=Spazzafumo |journal=Pelviperineology |volume=26 |issue=2 |date=June 2007 |pages=59–65 |access-date=August 7, 2007 |archive-date=January 31, 2009 |archive-url=https://web.archive.org/web/20090131101200/http://pelviperineology.org/practical/sonography_female_pelvic_floor_clinical_indications_and_techniques.html }}</ref>

=== Penis and scrotum ===
{{Main|Scrotal ultrasound|Penile ultrasonography}}
[[Scrotal ultrasonography]] is used in the evaluation of [[testicular pain]], and can help identify solid masses.<ref name="GrahamKeane2009">{{cite book|first1=Sam D.|last1=Graham|author2=Thomas E Keane|title=Glenn's Urologic Surgery|url=https://books.google.com/books?id=GahMzaKgMKAC&pg=PA433|access-date=1 July 2011|date=25 September 2009|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-9141-0|pages=433–}}</ref>

Ultrasound is an excellent method for the study of the [[penis]], such as indicated in trauma, priapism, erectile dysfunction or suspected [[Peyronie's disease]].<ref name="FernandesSouza2018">{{cite journal |last1=Fernandes |first1=Maitê Aline Vieira |last2=Souza |first2=Luis Ronan Marquez Ferreira de |last3=Cartafina |first3=Luciano Pousa |title=Ultrasound evaluation of the penis |journal=Radiologia Brasileira |date=23 July 2018 |volume=51 |issue=4 |pages=257–261 |doi=10.1590/0100-3984.2016.0152 |pmid=30202130 |pmc=6124582 }}</ref>

=== Musculoskeletal ===
[[Musculoskeletal]] ultrasound is used to examine tendons, muscles, nerves, ligaments, soft tissue masses, and bone surfaces.<ref>Arend CF. Ultrasound of the Shoulder. Porto Alegre: Master Medical Books; 2013. (Free access at [https://web.archive.org/web/20171224065120/http://www.shoulderus.com/sample-chapters/ultrasound-of-the-shoulder-book ShoulderUS.com]){{page needed|date=November 2013}}</ref>
It is helpful in diagnosing ligament sprains, muscles strains and joint pathology. It is an alternative or supplement to x-ray imaging in detecting fractures of the wrist, elbow and shoulder for patients up to 12 years<ref>{{cite journal |last1=Hübner |first1=U. |last2=Schlicht |first2=W. |last3=Outzen |first3=S. |last4=Barthel |first4=M. |last5=Halsband |first5=H. |title=Ultrasound in the diagnosis of fractures in children |journal=The Journal of Bone and Joint Surgery. British Volume |date=November 2000 |volume=82-B |issue=8 |pages=1170–1173 |doi=10.1302/0301-620x.82b8.10087|pmid=11132281 }}</ref> ([[Fracture sonography]]).

Quantitative ultrasound is an adjunct musculoskeletal test for myopathic disease in children;<ref>{{Cite journal|last1=Zaidman|first1=Craig M.|last2=van Alfen|first2=Nens|date=2016-04-01|title=Ultrasound in the Assessment of Myopathic Disorders|journal=Journal of Clinical Neurophysiology|volume=33|issue=2|pages=103–111|doi=10.1097/WNP.0000000000000245|pmid=27035250|s2cid=35805733}}</ref><ref>{{Cite journal|last1=Harris-Love|first1=Michael O.|last2=Monfaredi|first2=Reza|last3=Ismail|first3=Catheeja|last4=Blackman|first4=Marc R.|last5=Cleary|first5=Kevin|date=2014-01-01|title=Quantitative ultrasound: measurement considerations for the assessment of muscular dystrophy and sarcopenia|journal=Frontiers in Aging Neuroscience|volume=6|page=172|doi=10.3389/fnagi.2014.00172|pmc=4094839|pmid=25071570|doi-access=free}}</ref> estimates of lean body mass in adults;<ref>{{Cite journal|last1=Abe|first1=Takashi|last2=Loene|first2=Jeremy P.|last3=Young|first3=Kaelin C.|last4=Thiebaud|first4=Robert S.|last5=Nahar|first5=Vinayak K.|last6=Hollaway|first6=Kaitlyn M.|last7=Stover|first7=Caitlin D.|last8=Ford|first8=M. Allison|last9=Bass|first9=Martha A.|date=2015-02-01|title=Validity of ultrasound prediction equations for total and regional muscularity in middle-aged and older men and women|journal=Ultrasound in Medicine & Biology|volume=41|issue=2|pages=557–564|doi=10.1016/j.ultrasmedbio.2014.09.007|pmid=25444689}}</ref> proxy measures of muscle quality (i.e., tissue composition)<ref>{{Cite journal|last1=McGregor|first1=Robin A.|last2=Cameron-Smith|first2=David|last3=Poppitt|first3=Sally D.|author3-link=Sally Poppitt|date=2014-01-01|title=It is not just muscle mass: a review of muscle quality, composition and metabolism during ageing as determinants of muscle function and mobility in later life|journal=Longevity & Healthspan|volume=3|issue=1|page=9|doi=10.1186/2046-2395-3-9|pmc=4268803|pmid=25520782 |doi-access=free }}</ref> in older adults with [[sarcopenia]]<ref>{{Cite journal|last1=Watanabe|first1=Yuya|last2=Yamada|first2=Yosuke|last3=Fukumoto|first3=Yoshihiro|last4=Ishihara|first4=Tatsuro|last5=Yokoyama|first5=Keiichi|last6=Yoshida|first6=Tsukasa|last7=Miyake|first7=Motoko|last8=Yamagata|first8=Emi|last9=Kimura|first9=Misaka|date=2013-01-01|title=Echo intensity obtained from ultrasonography images reflecting muscle strength in elderly men|journal=Clinical Interventions in Aging|volume=8|pages=993–998|doi=10.2147/CIA.S47263|pmc=3732157|pmid=23926426 |doi-access=free }}</ref><ref>{{Cite journal|last1=Ismail|first1=Catheeja|last2=Zabal|first2=Johannah|last3=Hernandez|first3=Haniel J.|last4=Woletz|first4=Paula|last5=Manning|first5=Heather|last6=Teixeira|first6=Carla|last7=DiPietro|first7=Loretta|last8=Blackman|first8=Marc R.|last9=Harris-Love|first9=Michael O.|date=2015-01-01|title=Diagnostic ultrasound estimates of muscle mass and muscle quality discriminate between women with and without sarcopenia|journal=Frontiers in Physiology|volume=6|page=302|doi=10.3389/fphys.2015.00302|pmc=4625057|pmid=26578974|doi-access=free}}</ref>

Ultrasound can also be used for needle guidance in muscle or [[joint injection]]s, as in [[ultrasound-guided hip joint injection]].{{citation needed|date=July 2024}}

=== Kidneys ===
{{Main|Renal ultrasonography}}
In [[nephrology]], ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most pathological changes are distinguishable with ultrasound. It is an accessible, versatile, relatively economic, and fast aid for decision-making in patients with renal symptoms and for guidance in renal intervention.<ref name=Hansen2015>{{cite journal |last1=Hansen |first1=Kristoffer |last2=Nielsen |first2=Michael |last3=Ewertsen |first3=Caroline |title=Ultrasonography of the Kidney: A Pictorial Review |journal=Diagnostics |date=23 December 2015 |volume=6 |issue=1 |page=2 |doi=10.3390/diagnostics6010002 |pmid=26838799 |pmc=4808817 |doi-access=free }} [https://creativecommons.org/licenses/by/4.0/ (CC-BY 4.0)]</ref> Using [[B-mode imaging]], assessment of renal anatomy is easily performed, and US is often used as image guidance for renal interventions. Furthermore, novel applications in renal US have been introduced with contrast-enhanced ultrasound (CEUS), elastography and fusion imaging. However, renal US has certain limitations, and other modalities, such as CT (CECT) and MRI, should be considered for supplementary imaging in assessing renal disease.<ref name=Hansen2015/>

=== Venous access ===

Intravenous access, for the collection of blood samples to assist in diagnosis or laboratory investigation including blood culture, or for administration of intravenous fluids for fluid maintenance of replacement or blood transfusion in sicker patients, is a common medical procedure. The need for intravenous access occurs in the outpatient laboratory, in the inpatient hospital units, and most critically in the Emergency Room and Intensive Care Unit. In many situations, intravenous access may be required repeatedly or over a significant time period. In these latter circumstances, a needle with an overlying catheter is introduced into the vein and the catheter is then inserted securely into the vein while the needle is withdrawn.
The chosen veins are most frequently selected from the arm, but in challenging situations, a deeper vein from the neck ([[external jugular vein]]) or upper arm ([[subclavian vein]]) may need to be used.
There are many reasons why the selection of a suitable vein may be problematic.
These include, but are not limited to, obesity, previous injury to veins from inflammatory reaction to previous 'blood draws', previous injury to veins from recreational drug use.{{citation needed|date=August 2022}}

In these challenging situations, the insertion of a catheter into a vein has been greatly assisted by the use of ultrasound. The ultrasound unit may be 'cart-based' or 'handheld' using a linear transducer with a frequency of 10 to 15 [[megahertz]]. In most circumstances, choice of vein will be limited by the requirement that the vein is within 1.5 cms. from the skin surface.
The transducer may be placed longitudinally or transversely over the chosen vein.
Ultrasound training for intravenous cannulation is offered in most ultrasound training programs.{{citation needed|date=August 2022}}

== Mechanism ==
The creation of an image from sound has three steps – transmitting a [[sound wave]], receiving [[Echo (phenomenon)|echoes]], and interpreting those echoes.

=== Producing a sound wave ===
[[File:A modern medical ultrasound scanner.jpg|thumb|A modern medical ultrasound scanner]]
A sound wave is typically produced by a [[piezoelectric]] transducer encased in a plastic housing. Strong, short electrical pulses from the ultrasound machine drive the [[Ultrasonic sensor|transducer]] at the desired frequency. The [[frequencies]] can vary between 1 and 18 [[MHz]], though frequencies up to 50–100 megahertz have been used experimentally in a technique known as biomicroscopy in special regions, such as the anterior chamber of the eye.<ref>{{cite book |last1=Pavlin |first1=Charles |last2=Foster |first2=F. Stuart |year=1994 |title=Ultrasound Biomicroscopy of the Eye |publisher=Springer |isbn=978-0-387-94206-3}}</ref>

Older technology transducers focused their beam with physical lenses.{{citation needed|date=October 2021}} Contemporary technology transducers use [[digital antenna array]] techniques (piezoelectric elements in the transducer produce echoes at different times) to enable the ultrasound machine to change the direction and depth of focus. Near the transducer, the width of the ultrasound beam almost equals to the width of the transducer, after reaching a distance from the transducer (near zone length or [[Fresnel zone]]), the beam width narrows to half of the transducer width, and after that the width increases (far zone length or [[Fraunhofer diffraction|Fraunhofer's zone]]), where the lateral resolution decreases. Therefore, the wider the transducer width and the higher the frequency of ultrasound, the longer the Fresnel zone, and the lateral resolution can be maintained at a greater depth from the transducer.<ref>{{Cite journal |last1=Ng |first1=Alexander |last2=Swanevelder |first2=Justiaan |date=October 2011 |title=Resolution in ultrasound imaging |url=https://linkinghub.elsevier.com/retrieve/pii/S1743181617302068 |journal=Continuing Education in Anaesthesia, Critical Care & Pain |language=en |volume=11 |issue=5 |pages=186–192 |doi=10.1093/bjaceaccp/mkr030|doi-access=free |url-access=subscription }}</ref> Ultrasound waves travel in pulses. Therefore, a shorter pulse length requires higher bandwidth (greater number of frequencies) to constitute the ultrasound pulse.<ref name="Starkoff 2014">{{Cite journal |last=Starkoff |first=Brian |date=February 2014 |title=Ultrasound physical principles in today's technology |journal=Australasian Journal of Ultrasound in Medicine |language=en |volume=17 |issue=1 |pages=4–10 |doi=10.1002/j.2205-0140.2014.tb00086.x |pmc=5024924 |pmid=28191202}}</ref>

As stated, the sound is focused either by the shape of the transducer, a lens in front of the transducer, or a complex set of control pulses from the ultrasound scanner, in the [[beamforming]] or spatial filtering technique. This focusing produces an arc-shaped sound wave from the face of the transducer. The wave travels into the body and comes into focus at a desired depth.

Materials on the face of the transducer enable the sound to be transmitted efficiently into the body (often a rubbery coating, a form of [[impedance matching]]).<ref name="auto">{{cite web |last1=Leskiw |first1=Chris |last2=Gates |first2=Ian |title=EP2542914A1 - System and method for using orthogonally-coded active source signals for reflected signal analysis |url=https://patents.google.com/patent/EP2542914A1/en |website=Google Patents |publisher=European Patent Office |access-date=6 March 2024}}</ref> In addition, a water-based gel is placed between the patient's skin and the probe to facilitate ultrasound transmission into the body. This is because air causes total reflection of ultrasound; impeding the transmission of ultrasound into the body.<ref>{{cite book |last1=Ostensen |first1=Harald |title=Basic physics of ultrasound imaging |date=2005 |publisher=Diagnostic Imaging and Laboratory Technology - World Health Organisation |location=Geneva |pages=25–26 |url=https://apps.who.int/iris/bitstream/handle/10665/43179/9241592990_eng.pdf |access-date=2 October 2021}}</ref>

The sound wave is partially reflected from the layers between different tissues or scattered from smaller structures. Specifically, sound is reflected anywhere where there are acoustic impedance changes in the body: e.g. [[blood cell]]s in [[blood plasma]], small structures in organs, etc. Some of the reflections return to the transducer.<ref name="auto"/>

=== Receiving the echoes ===
The return of the sound wave to the transducer results in the same process as sending the sound wave, in reverse. The returned sound wave vibrates the transducer and the transducer turns the vibrations into electrical pulses that travel to the ultrasonic scanner where they are processed and transformed into a digital image.<ref name="WearableUSG">{{cite journal |last1=Srivastav |first1=A. |last2=Bhogi |first2=K. |last3=Mandal |first3=S. | last4=Sharad | first4=M.|title=An Adaptive Low-Complexity Abnormality Detection Scheme for Wearable Ultrasonography |journal=IEEE Transactions on Circuits and Systems |date=Aug 2019 |volume=66 |issue=8 |pages=1466–1470 |doi=10.1109/TCSII.2018.2881612 |bibcode=2019ITCSE..66.1466S |s2cid=117391787 }}</ref>

=== Forming the image ===
To make an image, the ultrasound scanner must determine two characteristics from each received echo:
# How long it took the echo to be received from when the sound was transmitted. (Time and distance are equivalent.)
# How strong the echo was.

Once the ultrasonic scanner determines these two, it can locate which pixel in the image to illuminate and with what intensity.

Transforming the received signal into a digital image may be explained by using a blank spreadsheet as an analogy. First picture a long, flat transducer at the top of the sheet. Send pulses down the 'columns' of the spreadsheet (A, B, C, etc.). Listen at each column for any return echoes. When an echo is heard, note how long it took for the echo to return. The longer the wait, the deeper the row (1,2,3, etc.). The strength of the echo determines the brightness setting for that cell (white for a strong echo, black for a weak echo, and varying shades of grey for everything in between.) When all the echoes are recorded on the sheet, a [[greyscale image]] has been accomplished.

In modern ultrasound systems, images are derived from the combined reception of echoes by multiple elements, rather than a single one. These elements in the transducer array work together to receive signals, a process essential for optimizing the ultrasonic beam's focus and producing detailed images. One predominant method for this is "delay-and-sum" beamforming. The time delay applied to each element is calculated based on the geometrical relationship between the imaging point, the transducer, and receiver positions. By integrating these time-adjusted signals, the system pinpoints focus onto specific tissue regions, enhancing image resolution and clarity. The utilization of multiple element reception combined with the delay-and-sum principles underpins the high-quality images characteristic of contemporary ultrasound scans.<ref>{{cite book |last1=Szabo |first1=Thomas L. |title=Diagnostic Ultrasound Imaging: Inside Out |date=2004 |publisher=Academic Press |isbn=978-0-12-680145-3}}</ref>

=== Displaying the image ===
Images from the ultrasound scanner are transferred and displayed using the [[DICOM]] standard.  Normally, very little post processing is applied.{{citation needed|date=August 2022}}

== Sound in the body ==
[[File:A medical ultrasound linear array probe, scan head, transducer.jpg|thumb|Curvilinear array transducer]]
Ultrasonography ([[sonography]]) uses a probe containing multiple acoustic [[transducer]]s to send pulses of sound into a material. Whenever a sound wave encounters a material with a different density (acoustical impedance), some of the sound wave is scattered but part is reflected back to the probe and is detected as an echo. The time it takes for the [[echo]] to travel back to the probe is measured and used to calculate the depth of the tissue interface causing the echo. The greater the difference between acoustic impedances, the larger the echo is. If the pulse hits gases or solids, the density difference is so great that most of the acoustic energy is reflected and it becomes impossible to progress further.{{citation needed|date=July 2024}}

The frequencies used for medical imaging are generally in the range of 1 to 18&nbsp;MHz Higher frequencies have a correspondingly smaller wavelength, and can be used to make more detailed sonograms. However, the attenuation of the sound wave is increased at higher frequencies, so penetration of deeper tissues necessitates a lower frequency (3–5&nbsp;MHz).

Penetrating deep into the body with sonography is difficult. Some acoustic energy is lost each time an echo is formed, but most of it (approximately <math>\textstyle 0.5 \frac{\mbox{dB}}{\mbox{cm depth}\cdot\mbox{MHz}}</math>) is lost from acoustic absorption. (See [[Acoustic attenuation]] for further details on modeling of acoustic attenuation and absorption.)

The speed of sound varies as it travels through different materials, and is dependent on the [[acoustical impedance]] of the material. However, the sonographic instrument assumes that the acoustic velocity is constant at 1540&nbsp;m/s. An effect of this assumption is that in a real body with non-uniform tissues, the beam becomes somewhat de-focused and image resolution is reduced.

To generate a [[2D computer graphics|2-D]] image, the ultrasonic beam is swept. A transducer may be swept mechanically by rotating or swinging or a 1-D [[phased array]] transducer may be used to sweep the beam electronically. The received data is processed and used to construct the image. The image is then a 2-D representation of the slice into the body.

[[3D computer graphics|3-D]] images can be generated by acquiring a series of adjacent 2-D images. Commonly a specialized probe that mechanically scans a conventional 2-D image transducer is used. However, since the mechanical scanning is slow, it is difficult to make 3D images of moving tissues. Recently, 2-D phased array transducers that can sweep the beam in 3-D have been developed. These can image faster and can even be used to make live 3-D images of a beating heart.

[[Doppler]] ultrasonography is used to study blood flow and muscle motion. The different detected speeds are represented in color for ease of interpretation, for example leaky heart valves: the leak shows up as a flash of unique color. Colors may alternatively be used to represent the amplitudes of the received echoes.

==Expansions==
An additional expansion of ultrasound is '''bi-planar ultrasound''', in which the probe has two 2D planes perpendicular to each other, providing more efficient localization and detection.<ref name=reves/> Furthermore, an '''omniplane''' probe can rotate 180° to obtain multiple images.<ref name=reves>Page 161 (part II > Two-dimensional Echocardiography) in: {{cite book |author1=Reves, J. G. |author2=Estafanous, Fawzy G. |author3=Barash, Paul G. |title=Cardiac anesthesia: principles and clinical practice |publisher=Lippincott Williams & Wilkins |location=Hagerstwon, MD |year=2001 |isbn=978-0-7817-2195-0 |url=https://books.google.com/books?id=45DKiUj1hLUC}}</ref> In [[3D ultrasound]], many 2D planes are digitally added together to create a 3-dimensional image of the object.

{{anchor|doppler}}

=== Doppler ultrasonography ===
{{Main|Doppler ultrasonography}}
[[File:ColourDopplerA.jpg|thumb|right|Duplex scan of the common carotid artery]]

[[Doppler ultrasonography]] employs the [[Doppler effect]] to assess whether structures (usually blood)<ref name="WearableUSG"/><ref name="L'Investigation vasculaire par ultrasonographie doppler">{{cite book | first= Claude | last= Franceschi | title=L'Investigation vasculaire par ultrasonographie doppler| publisher= Masson|year=1978 |isbn=978-2-225-63679-0}}</ref> are moving towards or away from the probe, and their relative velocity. By calculating the frequency shift of a particular sample volume, flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized, as an example. ''Color Doppler'' is the measurement of velocity by color scale. Color Doppler images are generally combined with gray scale ([[#Modes|B-mode]]) images to display ''duplex ultrasonography'' images.<ref>{{cite journal |last1=Saxena |first1=A |last2=Ng |first2=EYK |last3=Lim |first3=ST |title=Imaging modalities to diagnose carotid artery stenosis: progress and prospect. |journal=BioMedical Engineering OnLine |date=28 May 2019 |volume=18 |issue=1 |page=66 |doi=10.1186/s12938-019-0685-7 |pmid=31138235|pmc=6537161 |doi-access=free }}</ref> Uses include:
* [[Doppler echocardiography]] is the use of Doppler ultrasonography to examine the [[heart]].<ref>{{cite web|url=https://medlineplus.gov/ency/article/003869.htm|title=Echocardiogram|website=[[MedlinePlus]]|access-date=2017-12-15}}</ref> An echocardiogram can, within certain limits, produce accurate assessment of the direction of [[blood flow]] and the [[velocity]] of blood and cardiac tissue at any arbitrary point using the Doppler effect. Velocity measurements allow assessment of [[cardiac valve]] areas and function, abnormal communications between the left and right side of the heart, leaking of blood through the valves ([[valvular regurgitation]]), and calculation of the [[cardiac output]] and [[E/A ratio]]<ref name="Mohamed">[http://www.bioline.org.br/request?mj04008] Abdul Latif Mohamed, Jun Yong, Jamil Masiyati, Lee Lim, Sze Chec Tee. ''The Prevalence Of Diastolic Dysfunction In Patients With Hypertension Referred For Echocardiographic Assessment of Left Ventricular Function.'' Malaysian Journal of Medical Sciences, Vol. 11, No. 1, January 2004, pp. 66–74</ref> (a measure of [[diastolic dysfunction]]). Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related measurements of interest.
* [[Transcranial Doppler]] (TCD) and transcranial color Doppler (TCCD), measure the velocity of [[blood flow]] through the [[brain]]'s [[blood vessel]]s through the [[cranium]]. They are useful in the diagnosis of [[emboli]], [[stenosis]], [[vasospasm]] from a subarachnoid [[hemorrhage]] (bleeding from a ruptured [[aneurysm]]), and other problems.
* [[Doppler fetal monitor]]s use the Doppler effect to detect the [[fetal heartbeat]] during [[prenatal care]]. These are hand-held, and some models also display the [[heart rate]] in beats per minute (BPM). Use of this monitor is sometimes known as ''Doppler [[auscultation]]''. The Doppler fetal monitor is commonly referred to simply as a ''Doppler'' or ''fetal Doppler'' and provides information similar to that provided by a [[fetal stethoscope]].

=== Contrast ultrasonography (ultrasound contrast imaging) ===
{{Main|Contrast-enhanced ultrasound}}

A [[contrast medium]] for medical ultrasonography is a formulation of encapsulated gaseous microbubbles<ref>{{cite journal |doi=10.1111/j.1540-8175.1999.tb00144.x |title=Characteristics of SonoVue™ |year=1999 |last1=Schneider |first1=Michel |journal=Echocardiography |volume=16 |pages=743–746 |pmid=11175217 |issue=7, Pt 2|s2cid=73314302 }}</ref> to increase [[echogenicity]] of blood, discovered by Dr. Raymond Gramiak in 1968<ref>{{cite journal |doi=10.1097/00004424-196809000-00011 |title=Echocardiography of the Aortic Root |year=1968 |last1=Gramiak |first1=Raymond |last2=Shah |first2=Pravin M. |journal=Investigative Radiology |volume=3 |issue=5 |pages=356–66 |pmid=5688346}}</ref> and named [[contrast-enhanced ultrasound]]. This contrast [[medical imaging]] modality is used throughout the world,<ref>{{cite web|url=http://www.icus-society.org/attachments/article/103/ICUS%20CEUS%20Use%20Around%20the%20World-2.pdf |title=CEUS Around the World – The International Contrast Ultrasound Society (ICUS) |date=October 2013 |access-date=2013-10-27 |archive-url=https://web.archive.org/web/20131029213232/http://www.icus-society.org/attachments/article/103/ICUS%20CEUS%20Use%20Around%20the%20World-2.pdf |archive-date=October 29, 2013 }}</ref> for [[echocardiography]] in particular in the United States and for ultrasound [[radiology]] in [[Europe]] and [[Asia]].

Microbubbles-based contrast media is administered [[intravenously]] into the patient [[blood stream]] during the ultrasonography examination. Due to their size, the microbubbles remain confined in [[blood vessels]] without extravasating towards the [[interstitial fluid]]. An [[ultrasound]] contrast media is therefore purely intravascular, making it an ideal agent to image [[Biological system|organ]] microvasculature for [[Medical diagnosis|diagnostic]] purposes. A typical clinical use of contrast ultrasonography is detection of a [[hypervascular]] [[metastatic]] tumor, which exhibits a contrast uptake (kinetics of microbubbles concentration in blood circulation) faster than healthy [[biological tissue]] surrounding the [[tumor]].<ref>{{cite journal |doi=10.1016/j.ultrasmedbio.2012.09.002 |title=Guidelines and Good Clinical Practice Recommendations for Contrast Enhanced Ultrasound (CEUS) in the Liver – Update 2012 |year=2013 |last1=Claudon |first1=Michel |last2=Dietrich |first2=Christoph F. |last3=Choi |first3=Byung Ihn |last4=Cosgrove |first4=David O. |last5=Kudo |first5=Masatoshi |last6=Nolsøe |first6=Christian P. |last7=Piscaglia |first7=Fabio |last8=Wilson |first8=Stephanie R. |last9=Barr |first9=Richard G. |last10=Chammas |first10=Maria C. |last11=Chaubal |first11=Nitin G. |last12=Chen |first12=Min-Hua |last13=Clevert |first13=Dirk Andre |last14=Correas |first14=Jean Michel |last15=Ding |first15=Hong |last16=Forsberg |first16=Flemming |last17=Fowlkes |first17=J. Brian |last18=Gibson |first18=Robert N. |last19=Goldberg |first19=Barry B. |last20=Lassau |first20=Nathalie |last21=Leen |first21=Edward L.S. |last22=Mattrey |first22=Robert F. |last23=Moriyasu |first23=Fuminori |last24=Solbiati |first24=Luigi |last25=Weskott |first25=Hans-Peter |last26=Xu |first26=Hui-Xiong |journal=Ultrasound in Medicine & Biology |volume=39 |issue=2 |pages=187–210 |pmid=23137926 |author27=World Federation for Ultrasound in Medicine |author28=European Federation of Societies for Ultrasound|hdl=11585/144895 |s2cid=2224370 }}</ref> Other clinical applications using contrast exist, as in echocardiography to improve delineation of [[left ventricle]] for visualizing contractibility of [[heart]] muscle after a [[myocardial infarction]]. Finally, applications in quantitative perfusion<ref>{{cite journal |doi=10.1055/s-0031-1281676 |title=The EFSUMB Guidelines and Recommendations on the Clinical Practice of Contrast Enhanced Ultrasound (CEUS): Update 2011 on non-hepatic applications |year=2011 |last1=Piscaglia |first1=F. |last2=Nolsøe |first2=C. |last3=Dietrich |first3=C. |last4=Cosgrove |first4=D. |last5=Gilja |first5=O. |last6=Bachmann Nielsen |first6=M. |last7=Albrecht |first7=T. |last8=Barozzi |first8=L. |last9=Bertolotto |first9=M. |last10=Catalano |first10=O. |last11=Claudon |first11=M. |last12=Clevert |first12=D. |last13=Correas |first13=J. |last14=d'Onofrio |first14=M. |last15=Drudi |first15=F. |last16=Eyding |first16=J. |last17=Giovannini |first17=M. |last18=Hocke |first18=M. |last19=Ignee |first19=A. |last20=Jung |first20=E. |last21=Klauser |first21=A. |last22=Lassau |first22=N. |last23=Leen |first23=E. |last24=Mathis |first24=G. |last25=Saftoiu |first25=A. |last26=Seidel |first26=G. |last27=Sidhu |first27=P. |last28=Ter Haar |first28=G. |last29=Timmerman |first29=D. |last30=Weskott |first30=H. |journal=Ultraschall in der Medizin |volume=33 |pages=33–59 |pmid=21874631 |issue=1|doi-access=free }}</ref> (relative measurement of [[blood flow]]<ref>{{cite journal |doi=10.1098/rsfs.2011.0026 |title=Quantitative contrast-enhanced ultrasound imaging: A review of sources of variability |year=2011 |last1=Tang |first1=M.- X. |last2=Mulvana |first2=H. |last3=Gauthier |first3=T. |last4=Lim |first4=A. K. P. |last5=Cosgrove |first5=D. O. |last6=Eckersley |first6=R. J. |last7=Stride |first7=E. |journal=Interface Focus |volume=1 |issue=4 |pages=520–39 |pmid=22866229 |pmc=3262271}}</ref>) have emerged for identifying early patient response to anti-cancerous drug treatment (methodology and clinical study by Dr. Nathalie Lassau in 2011<ref>{{cite journal |doi=10.1148/radiol.10091870 |title=Advanced Hepatocellular Carcinoma: Early Evaluation of Response to Bevacizumab Therapy at Dynamic Contrast-enhanced US with Quantification—Preliminary Results |year=2010 |last1=Lassau |first1=N. |last2=Koscielny |first2=S. |last3=Chami |first3=L. |last4=Chebil |first4=M. |last5=Benatsou |first5=B. |last6=Roche |first6=A. |last7=Ducreux |first7=M. |last8=Malka |first8=D. |last9=Boige |first9=V. |journal=Radiology |volume=258 |pages=291–300 |pmid=20980447 |issue=1  }}</ref>), enabling the best oncological [[Therapeutic ultrasound|therapeutic]] options to be determined.<ref>{{cite journal |doi=10.1111/liv.12098 |title=Hepatocellular carcinoma treated with sorafenib: Early detection of treatment response and major adverse events by contrast-enhanced US |year=2013 |last1=Sugimoto |first1=Katsutoshi |last2=Moriyasu |first2=Fuminori |last3=Saito |first3=Kazuhiro |last4=Rognin |first4=Nicolas |last5=Kamiyama |first5=Naohisa |last6=Furuichi |first6=Yoshihiro |last7=Imai |first7=Yasuharu |journal=Liver International |volume=33 |issue=4 |pages=605–15 |pmid=23305331|s2cid=19338115 }}</ref>

[[File:Parametric Imaging of Vascular Signatures.jpg|thumb|Parametric imaging of vascular signatures (diagram)]]

In [[oncological]] practice of medical contrast ultrasonography, clinicians use 'parametric imaging of vascular signatures'<ref>{{cite journal |doi=10.1109/TUFFC.2010.1716 |title=Parametric imaging for characterizing focal liver lesions in contrast-enhanced ultrasound |year=2010 |last1=Rognin |first1=N G |last2=Arditi |first2=M |last3=Mercier |first3=L |last4=Frinking |first4=P J A |last5=Schneider |first5=M |last6=Perrenoud |first6=G |last7=Anaye |first7=A |last8=Meuwly |first8=J |last9=Tranquart |first9=F |journal=IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control |volume=57 |issue=11 |pages=2503–11 |pmid=21041137  |bibcode=2010ITUFF..57.2503R |s2cid=19339331 }}</ref> invented by Dr. Nicolas Rognin in 2010.<ref>{{cite web|title=Parametric images based on dynamic behavior over time|url=http://patentscope.wipo.int/search/en/WO2011026866|website= International Patent|publisher=World Intellectual Property Organization (WIPO) |vauthors=Rognin N, etal |pages=1–44|year=2010}}</ref> This method is conceived as a [[cancer]] aided diagnostic tool, facilitating characterization of a suspicious [[tumor]] ([[Malignant tumor|malignant]] versus [[benign]]) in an organ. This method is based on medical [[computational science]]<ref>{{cite journal |doi=10.1055/s-0032-1312894 |title=Perfusion Quantification in Contrast-Enhanced Ultrasound (CEUS) – Ready for Research Projects and Routine Clinical Use |year=2012 |last1=Tranquart |first1=F. |last2=Mercier |first2=L. |last3=Frinking |first3=P. |last4=Gaud |first4=E. |last5=Arditi |first5=M. |journal=Ultraschall in der Medizin |volume=33 |pages=S31–8 |pmid=22723027|s2cid=8513304 }}</ref><ref>{{cite journal |doi=10.1016/j.cag.2010.12.005 |title=Interactive visual analysis of contrast-enhanced ultrasound data based on small neighborhood statistics |year=2011 |last1=Angelelli |first1=Paolo |last2=Nylund |first2=Kim |last3=Gilja |first3=Odd Helge |last4=Hauser |first4=Helwig |journal=Computers & Graphics |volume=35 |issue=2 |pages=218–226}}</ref> to analyze a time sequence of ultrasound contrast images, a digital video recorded in real-time during patient examination. Two consecutive [[signal processing]] steps are applied to each [[pixel]] of the tumor:
# calculation of a vascular signature (contrast uptake difference with respect to healthy tissue surrounding the tumor);
# automatic [[Pattern recognition|classification]] of the vascular signature into a unique [[parameter]], the latter coded in one of the four following [[color]]s:
#* [[green]] for continuous hyper-enhancement (contrast uptake higher than healthy tissue one),
#* [[blue]] for continuous hypo-enhancement (contrast uptake lower than healthy tissue one),
#* [[red]] for fast hyper-enhancement (contrast uptake before healthy tissue one) or
#* [[yellow]] for fast hypo-enhancement (contrast uptake after healthy tissue one).

Once [[signal processing]] in each pixel is completed, a color spatial map of the parameter is displayed on a [[computer monitor]], summarizing all [[Blood vessel|vascular]] information of the tumor in a single image called a parametric image (see last figure of press article<ref>Barnes E, [http://www.auntminnie.com/index.aspx?sec=ser&sub=def&pag=dis&ItemID=91487 Contrast US processing tool shows malignant liver lesions], AuntMinnie.com, 2010.</ref> as clinical examples). This parametric image is interpreted by clinicians based on predominant colorization of the tumor: red indicates a suspicion of [[malignancy]] (risk of cancer), green or yellow – a high probability of benignity. In the first case (suspicion of [[malignant tumor]]), the clinician typically prescribes a biopsy to confirm the diagnostic or a [[CT scan]] examination as a second opinion. In the second case (quasi-certain of [[benign tumor]]), only a follow-up is needed with a contrast ultrasonography examination a few months later. The main clinical benefits are to avoid a systemic biopsy (with inherent risks of invasive procedures) of benign tumors or a CT scan examination exposing the patient to [[X-ray]] radiation. The parametric imaging of vascular signatures method proved to be effective in humans for characterization of tumors in the liver.<ref>{{cite journal |doi=10.1148/radiol.11101866 |title=Differentiation of Focal Liver Lesions: Usefulness of Parametric Imaging with Contrast-enhanced US |year=2011 |last1=Anaye |first1=A. |last2=Perrenoud |first2=G. |last3=Rognin |first3=N. |last4=Arditi |first4=M. |last5=Mercier |first5=L. |last6=Frinking |first6=P. |last7=Ruffieux |first7=C. |last8=Peetrons |first8=P. |last9=Meuli |first9=R. |last10=Meuwly |first10=J.-Y. |journal=Radiology |volume=261 |pages=300–10 |pmid=21746815 |issue=1|doi-access=free }}</ref> In a [[cancer screening]] context, this method might be potentially applicable to other organs such as [[Breast cancer|breast]]<ref>{{cite journal |doi=10.4048/jbc.2013.16.2.208 |title=Diagnostic Value of Contrast-Enhanced Ultrasound Parametric Imaging in Breast Tumors |year=2013 |last1=Yuan |first1=Zhang |last2=Quan |first2=Jiang |last3=Yunxiao |first3=Zhang |last4=Jian |first4=Chen |last5=Zhu |first5=He |last6=Liping |first6=Gong |journal=Journal of Breast Cancer |volume=16 |issue=2 |pages=208–13 |pmid=23843855 |pmc=3706868}}</ref> or [[Prostate cancer|prostate]].

=== Molecular ultrasonography (ultrasound molecular imaging) ===
The current future of contrast ultrasonography is in [[molecular imaging]] with potential clinical applications expected in [[cancer screening]] to detect [[malignant tumor]]s at their earliest stage of appearance. Molecular ultrasonography (or ultrasound molecular imaging) uses targeted microbubbles originally designed by Dr [[Alexander Klibanov (biologist)|Alexander Klibanov]] in 1997;<ref>{{cite journal |pmid=9240089 |year=1997|last1=Klibanov|first1=A. L. |last2=Hughes |first2=M. S. |last3=Marsh |first3=J. N. |last4=Hall |first4=C. S. |last5=Miller |first5=J. G. |last6=Wilble |first6=J. H. |last7=Brandenburger |first7=G. H. |title=Targeting of ultrasound contrast material. An in vitro feasibility study |volume=412 |pages=113–120 |journal=Acta Radiologica Supplementum}}</ref><ref>{{cite journal |doi=10.1016/S0169-409X(98)00104-5 |title=Targeted delivery of gas-filled microspheres, contrast agents for ultrasound imaging |year=1999 |last1=Klibanov |first1=A |journal=Advanced Drug Delivery Reviews |volume=37 |pages=139–157 |pmid=10837732 |issue=1–3}}</ref> such targeted microbubbles specifically bind or adhere to tumoral microvessels by targeting [[biomolecular]] cancer expression (overexpression of certain biomolecules that occurs during [[Angiogenesis|neo-angiogenesis]]<ref>{{cite journal |pmid=20027118 |year=2010 |last1=Pochon |first1=S |last2=Tardy |first2=I |last3=Bussat |first3=P |last4=Bettinger |first4=T |last5=Brochot |first5=J |last6=Von Wronski |first6=M |last7=Passantino |first7=L |last8=Schneider |first8=M |title=BR55: A lipopeptide-based VEGFR2-targeted ultrasound contrast agent for molecular imaging of angiogenesis |volume=45 |issue=2 |pages=89–95 |doi=10.1097/RLI.0b013e3181c5927c |journal=Investigative Radiology|s2cid=24089981 }}</ref><ref>{{cite journal |doi=10.2967/jnumed.109.068007 |title=Targeted Contrast-Enhanced Ultrasound Imaging of Tumor Angiogenesis with Contrast Microbubbles Conjugated to Integrin-Binding Knottin Peptides |year=2010 |last1=Willmann |first1=J. K. |last2=Kimura |first2=R. H. |last3=Deshpande |first3=N. |last4=Lutz |first4=A. M. |last5=Cochran |first5=J. R. |last6=Gambhir |first6=S. S. |journal=Journal of Nuclear Medicine |volume=51 |issue=3 |pages=433–40 |pmid=20150258 |pmc=4111897}}</ref> or [[inflammation]]<ref>{{cite journal |pmid=15052252 |year=2004 |last1=Lindner |first1=JR |title=Molecular imaging with contrast ultrasound and targeted microbubbles |volume=11 |issue=2 |pages=215–21 |doi=10.1016/j.nuclcard.2004.01.003 |journal=Journal of Nuclear Cardiology|s2cid=36487102 }}</ref> in malignant tumors). As a result, a few minutes after their injection in blood circulation, the targeted microbubbles accumulate in the malignant tumor; facilitating its localization in a unique ultrasound contrast image. In 2013, the very first exploratory [[clinical trial]] in humans for [[prostate cancer]] was completed at [[Amsterdam]] in the [[Netherlands]] by Dr. Hessel Wijkstra.<ref>{{ClinicalTrialsGov|NCT01253213|BR55 in Prostate Cancer: an Exploratory Clinical Trial}}</ref>

In molecular ultrasonography, the technique of [[acoustic radiation force]] (also used for [[shear wave elastography]]) is applied in order to literally push the targeted microbubbles towards microvessels wall; first demonstrated by Dr. Paul Dayton in 1999.<ref>{{cite journal |doi=10.1016/S0301-5629(99)00062-9 |title=Acoustic radiation force in vivo: A mechanism to assist targeting of microbubbles |year=1999 |last1=Dayton |first1=Paul |last2=Klibanov |first2=Alexander |last3=Brandenburger |first3=Gary |author4-link=Ferrara, Kathy |last4=Ferrara, Kathy |journal=Ultrasound in Medicine & Biology |volume=25 |issue=8 |pages=1195–1201 |pmid=10576262}}</ref> This allows maximization of binding to the malignant tumor; the targeted microbubbles being in more direct contact with cancerous biomolecules expressed at the inner surface of tumoral microvessels. At the stage of scientific [[preclinical]] research, the technique of acoustic radiation force was implemented as a prototype in clinical ultrasound systems and validated ''[[in vivo]]'' in 2D<ref>{{cite journal |doi=10.1016/j.ultrasmedbio.2012.03.018 |title=Effects of Acoustic Radiation Force on the Binding Efficiency of BR55, a VEGFR2-Specific Ultrasound Contrast Agent |year=2012 |last1=Frinking |first1=Peter J.A. |last2=Tardy |first2=Isabelle |last3=Théraulaz |first3=Martine |last4=Arditi |first4=Marcel |last5=Powers |first5=Jeffry |last6=Pochon |first6=Sibylle |last7=Tranquart |first7=François |journal=Ultrasound in Medicine & Biology |volume=38 |issue=8 |pages=1460–9 |pmid=22579540}}</ref> and 3D<ref>{{cite journal |doi=10.1016/j.ultrasmedbio.2011.12.005 |title=An In Vivo Validation of the Application of Acoustic Radiation Force to Enhance the Diagnostic Utility of Molecular Imaging Using 3-D Ultrasound |year=2012 |last1=Gessner |first1=Ryan C. |last2=Streeter |first2=Jason E. |last3=Kothadia |first3=Roshni |last4=Feingold |first4=Steven |last5=Dayton |first5=Paul A. |journal=Ultrasound in Medicine & Biology |volume=38 |issue=4 |pages=651–60 |pmid=22341052|pmc=3355521 }}</ref><ref>{{cite journal|last=Rognin N |title=Molecular Ultrasound Imaging Enhancement by Volumic Acoustic Radiation Force (VARF): Pre-clinical in vivo Validation in a Murine Tumor Model |journal=World Molecular Imaging Congress, Savannah, GA, USA |year=2013 |url=http://wmis2013.omnibooksonline.com/data/papers/P380.htm |display-authors=etal |archive-url=https://web.archive.org/web/20131011213605/http://wmis2013.omnibooksonline.com/data/papers/P380.htm |archive-date=October 11, 2013 }}</ref> imaging modes.

=== Elastography (ultrasound elasticity imaging) ===
{{Main|Elastography}}
Ultrasound is also used for elastography, which is a relatively new imaging modality that maps the elastic properties of soft tissue.<ref name=Wells>{{cite journal | author = Wells P. N. T. | year = 2011 | title = Medical ultrasound: imaging of soft tissue strain and elasticity | journal = Journal of the Royal Society, Interface | volume = 8 | issue = 64| pages = 1521–1549 | doi = 10.1098/rsif.2011.0054 | pmid = 21680780 | pmc = 3177611 | bibcode = 2011JRSI....8.1521W }}</ref><ref name=Sarv>{{cite journal|vauthors=Sarvazyan A, Hall TJ, Urban MW, Fatemi M, Aglyamov SR, Garra BS |pmc=3269947 |title=Overview of elastography–an emerging branch of medical imaging|journal=Current Medical Imaging Reviews |volume=7 |issue=4 |pages=255–282 |year=2011 |pmid=22308105 |doi=10.2174/157340511798038684}}</ref> This modality emerged in the last two decades. Elastography is useful in medical diagnoses as it can discern healthy from unhealthy tissue for specific organs/growths. For example, cancerous tumors will often be harder than the surrounding tissue, and diseased livers are stiffer than healthy ones.<ref name=Wells/><ref name=Sarv/><ref>{{cite journal|author1=Ophir, J. |author2=Céspides, I. |author3=Ponnekanti, H. |author4=Li, X. |title=Elastography: A quantitative method for imaging the elasticity of biological tissues|journal=Ultrasonic Imaging|volume=13|issue=2|pages=111–34|doi=10.1016/0161-7346(91)90079-W|pmid=1858217|year=1991}}</ref><ref>{{cite journal|author1=Parker, K J |author2=Doyley, M M |author3=Rubens, D J |title=Corrigendum: Imaging the elastic properties of tissue: The 20 year perspective|journal=Physics in Medicine and Biology|volume=57|issue=16|pages=5359–5360|doi=10.1088/0031-9155/57/16/5359|year=2012|bibcode=2012PMB....57.5359P|doi-access=free}}</ref>

There are many ultrasound elastography techniques.<ref name=Sarv/>

===Interventional ultrasonography===
Interventional ultrasonography involves [[biopsy]], emptying fluids, intrauterine [[Blood transfusion]] ([[Hemolytic disease of the newborn]]).
* [[Thyroid cyst]]s: High frequency thyroid [[ultrasound]] (HFUS) can be used to treat several gland conditions. The recurrent thyroid cyst that was usually treated in the past with surgery, can be treated effectively by a new procedure called percutaneous ethanol injection, or PEI.<ref>{{cite journal |last1=Halenka |first1=Milan |last2=Karasek |first2=David |last3=Schovanek |first3=Jan |last4=Frysak |first4=Zdenek |title=Safe and effective percutaneous ethanol injection therapy of 200 thyroid cysts |journal=Biomedical Papers |date=18 June 2020 |volume=164 |issue=2 |pages=161–167 |doi=10.5507/bp.2019.007|pmid=30945701 |s2cid=92999405 |doi-access=free }}</ref><ref>{{cite journal |last1=Ozderya |first1=Aysenur |last2=Aydin |first2=Kadriye |last3=Gokkaya |first3=Naile |last4=Temizkan |first4=Sule |title=Percutaneous Ethanol Injection for Benign Cystic and Mixed Thyroid Nodules |journal=Endocrine Practice |date=June 2018 |volume=24 |issue=6 |pages=548–555 |doi=10.4158/EP-2018-0013|pmid=29624094 |s2cid=4665114 }}</ref> With ultrasound guided placement of a 25 gauge needle within the cyst, and after evacuation of the cyst fluid, about 50% of the cyst volume is injected back into the cavity, under strict operator visualization of the needle tip. The procedure is 80% successful in reducing the cyst to minute size.
* Metastatic thyroid cancer neck lymph nodes: HFUS may also be used to treat metastatic thyroid cancer neck lymph nodes that occur in patients who either refuse, or are no longer candidates, for surgery. Small amounts of ethanol are injected under ultrasound guided needle placement. A power doppler blood flow study is done prior to injection. The blood flow can be destroyed and the node rendered inactive. Power doppler visualized blood flow can be eradicated, and there may be a drop in the cancer blood marker test, [[thyroglobulin]], TG, as the node become non-functional. Another interventional use for HFUS is to mark a cancer node prior to surgery to help locate the node cluster at the surgery. A minute amount of methylene dye is injected, under careful ultrasound guided placement of the needle on the anterior surface, but not in the node. The dye will be evident to the thyroid surgeon when opening the neck. A similar localization procedure with methylene blue, can be done to locate parathyroid adenomas.<ref name="YeapRobinson2017">{{cite journal |last1=Yeap |first1=Phey Ming |last2=Robinson |first2=Philip |title=Ultrasound Diagnostic and Therapeutic Injections of the Hip and Groin |journal=Journal of the Belgian Society of Radiology |date=16 December 2017 |volume=101 |issue=Suppl 2 |page=6 |doi=10.5334/jbr-btr.1371 |pmid=30498802 |pmc=6251072 |doi-access=free }}</ref>
* [[Joint injection]]s can be guided by medical ultrasound, such as in [[ultrasound-guided hip joint injection]]s.

=== Compression ultrasonography ===
Compression ultrasonography is when the probe is pressed against the skin. This can bring the target structure closer to the probe, increasing spatial resolution of it. Comparison of the shape of the target structure before and after compression can aid in diagnosis.

It is used in [[ultrasonography of deep venous thrombosis]], wherein absence of vein compressibility is a strong indicator of thrombosis.<ref name="JAMA">{{cite journal |doi=10.1136/bmj.316.7124.17 |title=Compression ultrasonography for diagnostic management of patients with clinically suspected deep vein thrombosis: Prospective cohort study |year=1998 |last1=Cogo |first1=A. |last2=Lensing |first2=A. W A |last3=Koopman |first3=M. M W |last4=Piovella |first4=F. |last5=Siragusa |first5=S. |last6=Wells |first6=P. S |last7=Villalta |first7=S. |last8=Büller |first8=H. R |last9=Turpie |first9=A. G G |last10=Prandoni |first10=P. |journal=BMJ |volume=316 |issue=7124 |pages=17–20 |pmid=9451260 |pmc=2665362}}</ref> Compression ultrasonography has both high [[sensitivity and specificity]] for detecting proximal deep vein thrombosis in symptomatic patients. Results are not reliable when the patient is asymptomatic, for example in high risk postoperative orthopedic patients.<ref name=medscape>{{cite journal |doi=10.7326/0003-4819-128-8-199804150-00011 |title=Noninvasive Diagnosis of Deep Venous Thrombosis |year=1998 |last1=Kearon |first1=Clive |journal=Annals of Internal Medicine |volume=128 |issue=8 |pages=663–77 |pmid=9537941 |last2=Julian |first2=JA |last3=Newman |first3=TE |last4=Ginsberg |first4=JS|s2cid=13467218 }}</ref><ref>{{cite journal |doi=10.1016/S0140-6736(94)90240-2 |title=Limitations of compression ultrasound for the detection of symptomless postoperative deep vein thrombosis |year=1994 |last1=Jongbloets |first1=L.M.M. |last2=Koopman |first2=M.M.W. |last3=Büller |first3=H.R. |last4=Ten Cate |first4=J.W. |last5=Lensing |first5=A.W.A. |journal=The Lancet |volume=343 |issue=8906 |pages=1142–4 |pmid=7910237|s2cid=23576444 }}</ref>

<gallery heights="180" widths="230">
File:Ultrasonography of a normal appendix without and with compression.jpg|A normal [[appendix (anatomy)|appendix]] without and with compression. Absence of compressibility indicates [[appendicitis]].<ref>{{cite journal|last1=Reddan|first1=Tristan|last2=Corness|first2=Jonathan|last3=Mengersen|first3=Kerrie|author3-link= Kerrie Mengersen |last4=Harden|first4=Fiona|title=Ultrasound of paediatric appendicitis and its secondary sonographic signs: providing a more meaningful finding|journal=Journal of Medical Radiation Sciences|date=March 2016|volume=63|issue=1|pages=59–66|doi=10.1002/jmrs.154|pmid=27087976|pmc=4775827}}</ref>
File:Ultrasonographic measurement of aortic diameter at the navel.svg|Compression is used in this ultrasonograph to get closer to the [[abdominal aorta]], making the [[superior mesenteric vein]] and the [[inferior vena cava]] look rather flat.
</gallery>
{{Anchor|Panoramic}}

===Panoramic ultrasonography===
[[File:Panoramic ultrasonography of biceps tendon rupture - Annotated.jpg|thumb|Panoramic ultrasonography of a proximal [[biceps tendon rupture]]. Top image shows the contralateral normal side, and lower image shows a retracted muscle, with a [[hematoma]] filling out the proximal space.]]
Panoramic ultrasonography is the digital [[image stitching|stitching]] of multiple ultrasound images into a broader one.<ref name=Kumar2010>{{cite journal|title=Panoramic Ultrasound|journal=Conference: Proceedings of the Second National Conference on Signal & Image Processing, at S.M.K. Fomra Institute of Technology Chennai, India|first=Suresh|last=Kumar|url=https://www.researchgate.net/publication/282816212}} April 2010</ref> It can display an entire abnormality and show its relationship to nearby structures on a single image.<ref name=Kumar2010/>

=== Multiparametric ultrasonography ===
Multiparametric ultrasonography (mpUSS) combines multiple ultrasound techniques to produce a composite result. For example, one study combined B-mode, colour Doppler, real-time elastography, and contrast-enhanced ultrasound, achieving an accuracy similar to that of [[multiparametric MRI]].<ref>{{cite journal |last1=Grey |first1=Alistair D R |last2=Scott |first2=Rebecca |last3=Shah |first3=Bina |last4=Acher |first4=Peter |last5=Liyanage |first5=Sidath |last6=Pavlou |first6=Menelaos |last7=Omar |first7=Rumana |last8=Chinegwundoh |first8=Frank |last9=Patki |first9=Prasad |last10=Shah |first10=Taimur T |last11=Hamid |first11=Sami |last12=Ghei |first12=Maneesh |last13=Gilbert |first13=Kayleigh |last14=Campbell |first14=Diane |last15=Brew-Graves |first15=Chris |last16=Arumainayagam |first16=Nimalan |last17=Chapman |first17=Alex |last18=McLeavy |first18=Laura |last19=Karatziou |first19=Angeliki |last20=Alsaadi |first20=Zayneb |last21=Collins |first21=Tom |last22=Freeman |first22=Alex |last23=Eldred-Evans |first23=David |last24=Bertoncelli-Tanaka |first24=Mariana |last25=Tam |first25=Henry |last26=Ramachandran |first26=Navin |last27=Madaan |first27=Sanjeev |last28=Winkler |first28=Mathias |last29=Arya |first29=Manit |last30=Emberton |first30=Mark |last31=Ahmed |first31=Hashim U |title=Multiparametric ultrasound versus multiparametric MRI to diagnose prostate cancer (CADMUS): a prospective, multicentre, paired-cohort, confirmatory study |journal=The Lancet Oncology |date=March 2022 |volume=23 |issue=3 |pages=428–438 |doi=10.1016/S1470-2045(22)00016-X |pmid=35240084 |s2cid=247178444 |hdl=10044/1/94492 |url=https://discovery.ucl.ac.uk/id/eprint/10145157/ |hdl-access=free }}</ref>

=== Speed-of-Sound Imaging ===
Speed-of-sound (SoS) imaging aims to find the spatial distribution of the SoS within the tissue. The idea is to find relative delay measurements for different transmission events and solve the limited-angle tomographic reconstruction problem using delay measurements and transmission geometry. Compared to shear-wave elastography, SoS imaging has better ex-vivo tissue differentiation<ref>{{cite journal |last1=Glozman |first1=Tanya |last2=Azhari |first2=Haim |title=A Method for Characterization of Tissue Elastic Properties Combining Ultrasonic Computed Tomography With Elastography |journal=Journal of Ultrasound in Medicine |date=March 2010 |volume=29 |issue=3 |pages=387–398 |doi=10.7863/jum.2010.29.3.387 |pmid=20194935 |s2cid=14869006 }}</ref> for benign and malignant tumors.<ref>{{cite journal |last1=Li |first1=Cuiping |last2=Duric |first2=Nebojsa |last3=Littrup |first3=Peter |last4=Huang |first4=Lianjie |title=In vivo Breast Sound-Speed Imaging with Ultrasound Tomography |journal=Ultrasound in Medicine & Biology |date=October 2009 |volume=35 |issue=10 |pages=1615–1628 |doi=10.1016/j.ultrasmedbio.2009.05.011 |pmid=19647920 |pmc=3915527 }}</ref><ref>{{cite journal |last1=Goss |first1=S. A. |last2=Johnston |first2=R. L. |last3=Dunn |first3=F. |title=Compilation of empirical ultrasonic properties of mammalian tissues. II |journal=The Journal of the Acoustical Society of America |date=July 1980 |volume=68 |issue=1 |pages=93–108 |doi=10.1121/1.384509 |pmid=11683186 |bibcode=1980ASAJ...68R..93G }}</ref><ref>{{cite journal |last1=Goss |first1=S. A. |last2=Johnston |first2=R. L. |last3=Dunn |first3=F. |title=Comprehensive compilation of empirical ultrasonic properties of mammalian tissues |journal=The Journal of the Acoustical Society of America |date=August 1978 |volume=64 |issue=2 |pages=423–457 |doi=10.1121/1.382016 |pmid=361793 |bibcode=1978ASAJ...64..423G }}</ref>

==Attributes==
As with all imaging modalities, ultrasonography has positive and negative attributes.

===Strengths===
* [[Muscle]], [[soft tissue]], and bone surfaces are imaged very well including the delineation of interfaces between solid and fluid-filled spaces.
* "Live" images can be dynamically selected, permitting diagnosis and documentation often rapidly. Live images also permit ultrasound-guided biopsies or injections, which can be cumbersome with other imaging modalities.
* Organ structure can be demonstrated.
* There are no known long-term side effects when used according to guidelines, and discomfort is minimal.
* Ability to image local variations in the mechanical properties of soft tissue.<ref>{{cite journal | author = Nightingale KR, Soo MS, Nightingale R, Trahey GE | year = 2002 | title = Acoustic radiation force impulse imaging: in vivo demonstration of clinical feasibility | journal = Ultrasound in Medicine & Biology | volume = 28 | issue = 2| pages = 227–235 | doi = 10.1016/s0301-5629(01)00499-9 | pmid = 11937286 }}</ref>
* Equipment is widely available and comparatively flexible.
* Small, easily carried scanners are available which permit bedside examinations.
* Transducers have become relatively inexpensive compared to other modes of investigation, such as [[CT scan|computed X-ray tomography]], [[DEXA]] or [[magnetic resonance imaging]].
* [[Image resolution#Spatial resolution|Spatial resolution]] is better in high frequency ultrasound transducers than most other imaging modalities.
* Use of an [[ultrasound research interface]] can offer a relatively inexpensive, real-time, and flexible method for capturing data required for specific research purposes of tissue characterization and development of new image processing techniques.

=== Weaknesses ===
[[File:Aorta duplication artifact 131206105958250c.jpg|thumb|Double aorta artifact in sonography due to difference in velocity of sound waves in muscle and fat]]
* Sonographic devices have trouble penetrating [[bone]]. For example, sonography of the adult brain is currently very limited.
* Sonography performs very poorly when there is gas between the transducer and the organ of interest, due to the extreme differences in [[acoustic impedance]]. For example, overlying gas in the gastrointestinal tract often makes ultrasound scanning of the [[pancreas]] difficult. This is also the case for [[subcutaneous emphysema]] when attempting to examine the lungs.<ref>{{cite journal |last1=Liu |first1=Xiaolei |last2=Si |first2=Si |last3=Wu |first3=Hui |title=Limitations of Bedside Lung Ultrasound in Neonatal Lung Diseases |journal=Frontiers in Pediatrics |date=April 2022 |volume=10 |article-number=855958 |doi=10.3389/fped.2022.855958 |doi-access=free |pmid=35558371 |pmc=9086677 }}</ref> Lung imaging however can be useful in demarcating pleural effusions, detecting [[heart failure]] and pneumonia.<ref>{{cite journal |last1=Llamas-Álvarez |first1=Ana M. |last2=Tenza-Lozano |first2=Eva M. |last3=Latour-Pérez |first3=Jaime |title=Accuracy of Lung Ultrasonography in the Diagnosis of Pneumonia in Adults |journal=Chest |date=February 2017 |volume=151 |issue=2 |pages=374–382 |doi=10.1016/j.chest.2016.10.039 |pmid=27818332 |s2cid=24399240 }}</ref>
* Even in the absence of bone or air, the depth penetration of ultrasound may be limited depending on the frequency of imaging. Consequently, there might be difficulties imaging structures deep in the body, especially in obese patients.
* Image quality and accuracy of diagnosis is limited with obese patients and overlying subcutaneous fat attenuates the sound beam. A lower frequency transducer is required with subsequent lower resolution.
* The method is operator-dependent. Skill and experience is needed to acquire good-quality images and make accurate diagnoses.
* There is no scout image as there is with CT and MRI. Once an image has been acquired there is no exact way to tell which part of the body was imaged.
* 80% of sonographers experience Repetitive Strain Injuries (RSI) or so-called Work-Related Musculoskeletal Disorders (WMSD) because of bad ergonomic positions.

==Risks and side-effects==
Ultrasonography is generally considered safe imaging,<ref>{{cite journal |doi=10.1148/radiology.173.2.2678243 |pmid=2678243 |year=1989 |last1=Merritt |first1=CR |title=Ultrasound safety: What are the issues? |volume=173 |issue=2 |pages=304–6 |journal=Radiology}}{{ dead link|date=May 2015}}</ref> with the World Health Organization stating:<ref>{{cite book |title=Training in diagnostic ultrasound: essentials, principles and standards: report of a WHO study group |date=1998 |publisher=World Health Organization |isbn=978-92-4-120875-8 |hdl=10665/42093 |page=2 }}</ref>
:"Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion".

Diagnostic ultrasound studies of the fetus are generally considered to be safe during pregnancy. However, this diagnostic procedure should be performed only when there is a valid medical indication, and the lowest possible ultrasonic exposure setting should be used to gain the necessary diagnostic information under the "as low as reasonably practicable" or [[ALARP]] principle.<ref>{{Cite web|title=Official Statement|url=https://www.aium.org/officialStatements/39|website=www.aium.org|access-date=2020-05-19|archive-date=April 20, 2021|archive-url=https://web.archive.org/web/20210420191242/https://aium.org/officialStatements/39}}</ref>

Although there is no evidence that ultrasound could be harmful to the fetus, medical authorities typically strongly discourage the promotion, selling, or leasing of ultrasound equipment for making "keepsake fetal videos".<ref name="keepsake"/><ref>{{cite web|last1=Lockwook|first1=Charles J.|title=Keepsake fetal ultrasounds (November 01, 2010)|url=http://contemporaryobgyn.modernmedicine.com/contemporary-obgyn/news/modernmedicine/modern-medicine-now/keepsake-fetal-ultrasounds?page=full|website=Modern Medicine Network|access-date=11 September 2017|archive-url=https://web.archive.org/web/20170911071553/http://contemporaryobgyn.modernmedicine.com/contemporary-obgyn/news/modernmedicine/modern-medicine-now/keepsake-fetal-ultrasounds?page=full|archive-date=2017-09-11|date=November 2010}}</ref>

===Studies on the safety of ultrasound===
* A meta-analysis of several ultrasonography studies published in 2000 found no statistically significant harmful effects from ultrasonography. It was noted that there is a lack of data on long-term substantive outcomes such as neurodevelopment.<ref>{{cite journal |pmid=11070816 |year=2000 |last1=Bricker |first1=L |last2=Garcia |first2=J |last3=Henderson |first3=J |last4=Mugford |first4=M |last5=Neilson |first5=J |last6=Roberts |first6=T |last7=Martin |first7=MA |title=Ultrasound screening in pregnancy: A systematic review of the clinical effectiveness, cost-effectiveness and women's views |volume=4 |issue=16 |pages=i–vi, 1–193 |journal=Health Technology Assessment|doi=10.3310/hta4160 |doi-access=free }}</ref>
* A study at the [[Yale School of Medicine]] published in 2006 found a small but significant correlation between prolonged and frequent use of ultrasound and abnormal neuronal migration in mice.<ref>{{cite journal |doi=10.1073/pnas.0605294103 |title=Prenatal exposure to ultrasound waves impacts neuronal migration in mice |year=2006 |last1=Ang |first1=E. S. B. C. |last2=Gluncic |first2=V. |last3=Duque |first3=A. |last4=Schafer |first4=M. E. |last5=Rakic |first5=P. |journal=Proceedings of the National Academy of Sciences |volume=103 |issue=34 |pages=12903–10 |pmid=16901978 |pmc=1538990|bibcode=2006PNAS..10312903A |doi-access=free }}{{primary source inline|date=April 2013}}</ref>
* A study performed in Sweden in 2001<ref>{{cite journal |doi=10.1097/00001648-200111000-00007 |title=Sinistrality—a side-effect of prenatal sonography: A comparative study of young men |year=2001 |last1=Kieler |first1=Helle |last2=Cnattingius |first2=Sven |last3=Haglund |first3=Bengt |last4=Palmgren |first4=Juni |last5=Axelsson |first5=Ove |journal=Epidemiology |volume=12 |issue=6 |pages=618–23 |pmid=11679787|s2cid=32614593 |doi-access=free }}{{primary source inline|date=April 2013}}</ref> has shown that subtle effects of neurological damage linked to ultrasound were implicated by an increased incidence in left-handedness in boys (a marker for brain problems when not hereditary) and speech delays.<ref>{{cite journal |doi=10.1136/bmj.307.6897.159 |title=Routine ultrasonography in utero and subsequent handedness and neurological development |year=1993 |last1=Salvesen |first1=K A |last2=Vatten |first2=L J |last3=Eik-Nes |first3=S H |last4=Hugdahl |first4=K |last5=Bakketeig |first5=L S |journal=BMJ |volume=307 |issue=6897 |pages=159–64 |pmid=7688253 |pmc=1678377}}{{primary source inline|date=April 2013}}</ref><ref>{{cite journal |doi=10.1016/S0378-3782(97)00097-2|year=1998 |title=Routine ultrasound screening in pregnancy and the children's subsequent handedness |last1=Kieler |first1=Helle |last2=Axelsson |first2=Ove |last3=Haglund |first3=Bengt |last4=Nilsson |first4=Staffan |last5=Salvesen |first5=Kjell Å. |journal=Early Human Development |volume=50 |issue=2 |pages=233–45 |pmid=9483394}}{{primary source inline|date=April 2013}}</ref>
** The above findings, however, were not confirmed in a follow-up study.<ref>{{cite journal |doi=10.1002/uog.8962 |pmid=21305639 |title=Handedness in the Helsinki Ultrasound Trial |year=2011 |last1=Heikkilä |first1=K. |last2=Vuoksimaa |first2=E. |last3=Oksava |first3=K. |last4=Saari-Kemppainen |first4=A. |last5=Iivanainen |first5=M. |journal=Ultrasound in Obstetrics & Gynecology |volume=37 |issue=6 |pages=638–642|s2cid=23916007 |doi-access=free }}{{primary source inline|date=April 2013}}</ref>
** A later study, however, performed on a larger sample of 8865 children, has established a statistically significant, albeit weak association of ultrasonography exposure and being non-right handed later in life.<ref>{{cite journal |doi=10.1002/uog.9055 |pmid=21584892 |title=Ultrasound in pregnancy and non-right handedness: Meta-analysis of randomized trials |year=2011 |last1=Salvesen |first1=K. Å. |journal=Ultrasound in Obstetrics & Gynecology |volume=38 |issue=3 |pages=267–271|s2cid=5135695 |doi-access=free }}</ref>

== Regulation ==
Diagnostic and [[therapeutic ultrasound]] equipment is regulated in the US by the [[Food and Drug Administration]], and worldwide by other national regulatory agencies. The FDA limits acoustic output using several metrics; generally, other agencies accept the FDA-established guidelines.

Currently, [[New Mexico]], [[Oregon]], and [[North Dakota]] are the only US states that regulate diagnostic medical sonographers.<ref>[http://www.ardms.org/Discover-ARDMS/about-us/Pages/Legislation.aspx Legislation]. ardms.org</ref> Certification examinations for sonographers are available in the US from three organizations: the [[American Registry for Diagnostic Medical Sonography]], [[Cardiovascular Credentialing International]] and the [[American Registry of Radiologic Technologists]].<ref>{{Cite web|title=Medical Technologist Certification & Degree Programs|url=https://www.medicaltechnologyschools.com/|website=MTS|language=en-US|access-date=2020-05-19}}</ref>

The primary regulated metrics are [[Mechanical Index]] (MI), a metric associated with the cavitation bio-effect, and Thermal Index (TI) a metric associated with the tissue heating bio-effect. The FDA requires that the machine not exceed established limits, which are reasonably conservative in an effort to maintain diagnostic ultrasound as a safe imaging modality. This requires [[Industry self-regulation|self-regulation]] on the part of the manufacturer in terms of machine calibration.<ref>{{cite book |chapter-url=http://sonoworld.com/Client/Fetus/html/doppler/capitulos-html/chapter_02.htm |chapter=Safety of diagnostic ultrasound in fetal scanning |author=Deane, Collin |year=2002 |title=Doppler in Obstetrics |editor-first1=Kypros |editor-last1=Nicolaides |editor-first2=Giuseppe |editor-last2=Rizzo |editor-first3=Kurt |editor-last3=Hecker |editor-first4=Renato |editor-last4=Ximenes |access-date=December 4, 2014 |archive-date=January 4, 2022 |archive-url=https://web.archive.org/web/20220104181032/https://sonoworld.com/Client/Fetus/html/doppler/capitulos-html/chapter_02.htm }}</ref>

Ultrasound-based pre-natal care and sex screening technologies were launched in India in the 1980s. With concerns about its misuse for [[sex-selective abortion]], the Government of India passed the [[Pre-Conception and Pre-Natal Diagnostic Techniques Act, 1994|Pre-natal Diagnostic Techniques Act (PNDT)]] in 1994 to distinguish and regulate legal and illegal uses of ultrasound equipment.<ref>[http://jskvrc.gov.in/ipas/2.pdf MTP and PCPNDT Initiatives Report] {{Webarchive|url=https://web.archive.org/web/20140601012501/http://jskvrc.gov.in/ipas/2.pdf |date=2014-06-01 }} Government of India (2011)</ref> The law was further amended as the Pre-Conception and Pre-natal Diagnostic Techniques (Regulation and Prevention of Misuse) (PCPNDT) Act in 2004 to deter and punish prenatal sex screening and sex selective abortion.<ref>[https://web.archive.org/web/20170502044453/http://www.wbhealth.gov.in/download/IMPLEMENTATION%20OF%20THE%20PCPNDT%20ACT%20IN%20INDIA.pdf IMPLEMENTATION OF THE PCPNDT ACT IN INDIA – Perspectives and Challenges]. Public Health Foundation of India, Supported by United Nations FPA (2010)</ref> It is currently illegal and a punishable crime in India to determine or disclose the sex of a fetus using ultrasound equipment.<ref>{{cite web|url=http://mohfw.nic.in/THE%20PNDT%20ACT%20%28PRINCIPAL%20ACT%291994.htm |title=THE PRE-NATAL DIAGNOSTIC TECHNIQUES (REGULATION AND PREVENTION OF MISUSE) ACT, 1994 |date=20 September 1994 |website=mohfw.nic.in |archive-url=https://web.archive.org/web/20050124122932/http://mohfw.nic.in/THE%20PNDT%20ACT%20%28PRINCIPAL%20ACT%291994.htm |archive-date=24 January 2005 }}</ref>

== Use in other animals ==
Ultrasound is also a valuable tool in [[veterinary medicine]], offering the same non-invasive imaging that helps in the diagnosis and monitoring of conditions in animals.

==History==
After the [[French people|French]] [[physicist]] [[Pierre Curie]]'s discovery of [[piezoelectricity]] in 1880, ultrasonic waves could be deliberately generated for industry. In 1940, the [[American people|American]] acoustical physicist [[Floyd Firestone]] devised the first ultrasonic echo imaging device, the Supersonic Reflectoscope, to detect internal flaws in metal castings. In 1941, [[Austrian people|Austrian]] [[neurologist]] [[Karl Theo Dussik]], in collaboration with his brother, Friedrich, a physicist, was likely the first person to image the human body ultrasonically, outlining the ventricles of a human brain.<ref>{{Cite journal |pmc=2170493 |author1=Siddharth, S. |author2=Goyal, A. |title=The origin of echocardiography |journal=Texas Heart Institute Journal |volume= 34|issue= 4|pages= 431–438|year= 2007|pmid= 18172524}}</ref><ref>Levine, H., III (2010). ''Medical Imaging''. Santa Barbara, California: ABC-CLIO, p. 62, describing earlier not completely successful attempt by the brothers to image a brain in 1937, which may be the same experiment.</ref> Ultrasonic energy was first applied to the human body for medical purposes by Dr&nbsp;[[George Ludwig]] at the Naval Medical Research Institute, [[Bethesda, Maryland]], in the late 1940s.<ref name="AIUM">{{cite web | title=History of the AIUM | url=http://www.aium.org/aboutAIUM/timeline/1950.asp | access-date=November 15, 2005 |archive-url = https://web.archive.org/web/20051103064941/http://www.aium.org/aboutAIUM/timeline/1950.asp  |archive-date = November 3, 2005}}</ref><ref name="ObGyn-Ultrasound">{{cite web|title=The History of Ultrasound: A collection of recollections, articles, interviews and images |publisher=www.obgyn.net |url=http://www.obgyn.net/us/us.asp?page=/us/news_articles/ultrasound_history/asp-history-toc |access-date=2006-05-11 |archive-url=https://web.archive.org/web/20060805163201/http://www.obgyn.net/us/us.asp?page=%2Fus%2Fnews_articles%2Fultrasound_history%2Fasp-history-toc |archive-date=5 August 2006 }}</ref> [[English people|English]]-born physicist [[John J. Wild|John Wild]] (1914–2009) first used ultrasound to assess the thickness of [[bowel]] tissue as early as 1949; he has been described as the "father of medical ultrasound".<ref>{{cite journal |doi=10.1136/bmj.b4428 |title=John Wild |year=2009 |last1=Watts |first1=G. |journal=BMJ |volume=339 |article-number=b4428|s2cid=220114494 }}</ref> Subsequent advances took place concurrently in several countries but it was not until 1961 that David Robinson and George Kossoff's work at the [[Australia]]n [[Department of Health]] resulted in the first commercially practical water bath ultrasonic scanner.<ref>{{Cite web|url=https://www.asum.com.au/wp-content/uploads/2015/09/Ultrasound-Australian-Innovation.pdf|title=Australian Ultrasound Innovation}}</ref> In 1963 Meyerdirk & Wright launched production of the first commercial, hand-held, articulated arm, compound contact B-mode scanner, which made ultrasound generally available for medical use.

===France===
Léandre Pourcelot, a researcher and teacher at INSA ([[Institut National des Sciences Appliquées]]), Lyon, co-published a report in 1965 at the Académie des sciences, "Effet Doppler et mesure du débit sanguin" ("Doppler effect and measure of the blood flow"), the basis of his design of a Doppler flow meter in 1967.

===Scotland===
Parallel developments in [[Glasgow]], Scotland by Professor [[Ian Donald]] and colleagues at the [[Glasgow Royal Maternity Hospital]] (GRMH) led to the first diagnostic applications of the technique.<ref>{{Cite Q|Q29581634}}</ref> Donald was an [[obstetrician]] with a self-confessed "childish interest in machines, electronic and otherwise", who, having treated the wife of one of the company's directors, was invited to visit the Research Department of boilermakers [[Doosan Babcock|Babcock & Wilcox]] at [[Renfrew]]. He adapted their industrial ultrasound equipment to conduct experiments on various anatomical specimens and assess their ultrasonic characteristics. Together with the medical physicist [[Tom Brown (engineer)|Tom Brown]].<ref name="LatU">{{cite book|title=Looking at the Unborn: Historical aspects of obstetric ultrasound|url=https://archive.org/details/lookingatunbornh00witn|year=2000|publisher=[[History of Modern Biomedicine Research Group]]|isbn=978-1-84129-011-9|url-access=registration}}</ref> and fellow obstetrician [[John MacVicar]], Donald refined the equipment to enable differentiation of pathology in live volunteer patients. These findings were reported in ''[[The Lancet]]'' on 7 June 1958<ref>{{cite journal |doi=10.1016/S0140-6736(58)91905-6 |title=Investigation of Abdominal Masses by Pulsed Ultrasound |year=1958 |last1=Donald |first1=Ian |last2=MacVicar |first2=J |last3=Brown |first3=T.G |journal=The Lancet |volume=271 |issue=7032 |pages=1188–95 |pmid=13550965}}</ref> as "Investigation of Abdominal Masses by Pulsed Ultrasound" – possibly one of the most important papers published in the field of diagnostic [[medical imaging]].

At GRMH, Professor Donald and James Willocks then refined their techniques to obstetric applications including [[fetal]] head measurement to assess the size and growth of the fetus. With the opening of the new Queen Mother's Hospital in [[Yorkhill]] in 1964, it became possible to improve these methods even further. [[Stuart Campbell (Obstetrician and Gynaecologist)|Stuart Campbell]]'s pioneering work on fetal [[cephalometry]] led to it acquiring long-term status as the definitive method of study of foetal growth. As the technical quality of the scans was further developed, it soon became possible to study pregnancy from start to finish and diagnose its many complications such as multiple pregnancy, fetal abnormality and ''[[placenta praevia]]''. Diagnostic ultrasound has since been imported into practically every other area of medicine.

===Sweden===
Medical ultrasonography was used in 1953 at [[Lund University]] by [[cardiologist]] [[Inge Edler]] and [[Gustav Ludwig Hertz]]'s son [[Carl Hellmuth Hertz]], who was then a graduate student at the university's department of [[nuclear physics]].

Edler had asked Hertz if it was possible to use [[radar]] to look into the body, but Hertz said this was [[millimeter wave scanner|impossible]]. However, he said, it might be possible to use ultrasonography. Hertz was familiar with using ultrasonic reflectoscopes of the American acoustical physicist [[Floyd Firestone]]'s invention for [[nondestructive testing|nondestructive materials testing]], and together Edler and Hertz developed the idea of applying this methodology in medicine.

The first successful measurement of heart activity was made on October 29, 1953, using a device borrowed from the ship construction company [[Kockums]] in [[Malmö]]. On December 16 the same year, the method was applied to generate an echo-encephalogram (ultrasonic probe of the [[brain]]). Edler and Hertz published their findings in 1954.<ref>{{cite journal |doi=10.1111/j.1475-097X.2004.00539.x |title=The Use of Ultrasonic Reflectoscope for the Continuous Recording of the Movements of Heart Walls |year=2004 |last1=Edler |first1=I. |last2=Hertz |first2=C. H. |journal=Clinical Physiology and Functional Imaging |volume=24 |issue=3 |pages=118–36 |pmid=15165281|s2cid=46092067 }}</ref>

===United States===
In 1962, after about two years of work, Joseph Holmes, William Wright, and Ralph Meyerdirk developed the first compound contact B-mode scanner. Their work had been supported by [[U.S. Public Health Services]] and the [[University of Colorado Denver|University of Colorado]]. Wright and Meyerdirk left the university to form Physionic Engineering Inc., which launched the first commercial hand-held articulated arm compound contact B-mode scanner in 1963. This was the start of the most popular design in the history of ultrasound scanners.<ref>{{cite web | last = Woo | first = Joseph | title = A short History of the development of Ultrasound in Obstetrics and Gynecology | publisher = ob-ultrasound.net | year = 2002 | url = http://www.ob-ultrasound.net/history1.html | access-date = 2007-08-26 }}</ref>

In the late 1960s [[Gene Strandness]] and the bio-engineering group at the [[University of Washington]] conducted research on Doppler ultrasound as a diagnostic tool for vascular disease. Eventually, they developed technologies to use duplex imaging, or Doppler in conjunction with B-mode scanning, to view vascular structures in real time while also providing hemodynamic information.<ref>{{cite journal|journal=Journal of Ultrasound|volume= 21 |issue=11 |pages=1323–1325 |doi=10.1067/mva.2002.123028 |title=D. Eugene Strandness, Jr, MD, 1928–2002 |last=Zierler |first=R. Eugene |date=2002|doi-access=free }}</ref>

The first demonstration of color Doppler was by Geoff Stevenson, who was involved in the early developments and medical use of Doppler shifted ultrasonic energy.<ref>{{cite book|title=Medical Imaging Past Present and Future: 2 ARRT category A continuing education credits are available by way of an online post test at XRayCeRT.com|url=https://books.google.com/books?id=DForAgAAQBAJ|publisher=XRayCeRT|id=GGKEY:6WU7UCYWQS7}}</ref>

==Manufacturers==
Major manufacturers of Medical Ultrasound Devices and Equipment are:<ref>{{cite web|url=https://www.fortunebusinessinsights.com/industry-reports/ultrasound-equipment-market-100515|title=Ultrasound Equipment Market Size, Share & Covid-19 Impact Analysis|date=September 2021|access-date=17 April 2022}}</ref>
* {{flagicon|Japan}} [[Canon Medical Systems Corporation]]
* {{flagicon|Italy}} [[Esaote]]
* {{flagicon|USA}} [[GE Healthcare]]
* {{flagicon|Japan}} [[Fujifilm]]
* {{flagicon|China}} [[Mindray Medical International Limited]]
* {{flagicon|Netherlands}} [[Koninklijke Philips N.V.]]
* {{flagicon|Korea}} [[Samsung Medison]]
* {{flagicon|Germany}} [[Siemens Healthineers]]

== Gallery ==
<gallery>

Ultrasound result.jpg|An ultrasound result on fetal biometry printed on a piece of paper

Hip joint injection by anterior longitudinal approach.jpg|[[Ultrasound-guided hip joint injection]]

</gallery>

==See also==

{{col div|colwidth=30em}}
* [[Ultrasound]] ([[3D ultrasound]])
* [[Doppler fetal monitor]]
* [[Elastography]]
* [[POCUS]]
* [[Polybiography]]
* [[Radiographer]]
* [[Voluson 730]]
{{colend}}

== Explanatory notes ==
{{Reflist|group="note"|1}}

==References==
{{Reflist|30em}}

==External links==
{{Commons category}}
* [http://www.ob-ultrasound.net/ingehertz.html About the discovery of medical ultrasonography] on ob-ultrasound.net
* [http://www.ob-ultrasound.net/history1.html History of medical sonography (ultrasound)] on ob-ultrasound.net

{{Medical imaging}}
{{obstetrical procedures}}
{{Authority control}}

{{DEFAULTSORT:Medical Ultrasonography}}
[[Category:Medical imaging]]
[[Category:Acoustics]]
[[Category:Medical equipment]]
[[Category:Medical ultrasonography| ]]
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[[Category:Australian inventions]]