FACTOID # 15: A mere 0.8% of West Virginians were born in a foreign country.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Medical ultrasonography

Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structures and possible pathologies or lesions. Obstetric sonography is commonly used during pregnancy and is widely recognized by the public. There are a plethora of diagnostic and therapeutic applications practiced in medicine. Night writing was a system of code that used symbols of twelve dots arranged as two columns of six dots. ... For other uses, see Ultrasound (disambiguation). ... Medical imaging designates the ensemble of techniques and processes used to create images of the human body (or parts thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). ... Skin lesions caused by Chickenpox A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. ... This article is about human pregnancy in biological females. ...


In physics the term "ultrasound" applies to all acoustic energy with a frequency above human hearing (20,000 hertz or 20 kilohertz). Typical diagnostic sonographic scanners operate in the frequency range of 2 to 18 megahertz, hundreds of times greater than this limit. The choice of frequency is a trade-off between spatial resolution of the image and imaging depth: lower frequencies produce less resolution but image deeper into the body. This article is about the SI unit of frequency. ...

A fetus in the womb, viewed in a sonogram
A fetus in the womb, viewed in a sonogram
"3D ultrasound" of a developing fetus at 29 weeks
"3D ultrasound" of a developing fetus at 29 weeks

Contents

ImageMetadata File history File links Baby_in_ultrasound. ... ImageMetadata File history File links Baby_in_ultrasound. ... Image File history File links 3dultrasound. ... Image File history File links 3dultrasound. ... 4D Ultrasound (also known as 3D/4D Ultrasound) is the most advanced technology used by sonographers during pregnancy to evaluate the unborn fetus. ...

Diagnostic applications

Sonography (ultrasonography) is widely used in medicine. It is possible to perform diagnosis or therapeutic procedures with the guidance of sonography (for instance biopsies or drainage of fluid collections). Sonographers are medical professionals who perform scans for diagnostic purposes. Sonographers typically use a hand-held probe (called a transducer) that is placed directly on and moved over the patient. A water-based gel is used to couple the ultrasound between the transducer and patient. For the chemical substances known as medicines, see medication. ... In general, diagnosis (plural diagnoses) has two distinct dictionary definitions. ... Brain biopsy A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ... Sonographers are medical professionals who operate ultrasonic imaging devices to produce diagnostic images and scans, videos, or 3D volumes of anatomy and diagnostic data. ... This article is about people called professionals. ...


Sonography is effective for imaging soft tissues of the body. Superficial structures such as muscles, tendons, testes, breast and the neonatal brain are imaged at a higher frequency (7-18 MHz), which provides better axial and lateral resolution. Deeper structures such as liver and kidney are imaged at a lower frequency 1-6 MHz with lower axial and lateral resolution but greater penetration. For other uses of Muscles, see Muscles (disambiguation). ... A tendon (or sinew) is a tough band of fibrous connective tissue that connects muscle to bone and is built to withstand tension. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... For other uses, see Breast (disambiguation). ... A human infant The word Infant derives from the Latin in-fans, meaning unable to speak. ... For other uses, see Frequency (disambiguation). ... Angular resolution describes the resolving power of any optical device such as a telescope, a microscope, a camera, or an eye. ...


Medical sonography is used in, for example:

A general-purpose sonographic machine may be able to be used for most imaging purposes. Usually specialty applications may be served only by use of a specialty transducer. The dynamic nature of many studies generally requires specialized features in a sonographic machine for it to be effective; such as endovaginal, endorectal, or transesophageal transducers. Cardiology is the branch of medicine pertaining to the heart. ... An echocardiogram. ... Endocrinology is a branch of medicine dealing with disorders of the endocrine system and its specific secretions called hormones. ... Gastroenterology (MeSH heading[2] ) is the branch of medicine where the digestive system and its disorders are studied. ... The shamefulness associated with the examination of female genitalia has long inhibited the science of gynaecology. ... Gynecologic ultrasonography or Gyn sonography refers to the application of medical ultrasonography to the female pelvic organs, specifically the uterus, the ovaries, the Fallopian tubes, as well as the bladder, the Pouch of Douglas, and any findings in the pelvis of relevance outsite of pregnancy. ... Obstetrics (from the Latin obstare, to stand by) is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth). ... Obstetric sonogram of a fetus at 16 weeks. ... This article is about the branch of medicine. ... A-scan ultrasound biometry, commonly referred to as an A-scan, is routine type of diagnostic test used in ophthalmology. ... B-scan ultrasonography, or B-scan, is a diagnostic test used in ophthalmology to produce a two-dimensional, cross-sectional view of the eye and the orbit. ... This article or section is in need of attention from an expert on the subject. ... The human musculoskeletal system is the musculoskeletal system that gives us the ability to move. ... f you all The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... Intravascular ultrasound (IVUS) is an medical imaging methodology using (a) specially designed long thin complex manufactured catheters attached to (b) computerized ultrasound equipment. ... Needle aspiration biopsy is a procedure performed to diagnose and treat certain kind of illnesses. ... An injection is a method of putting liquid into the body with a hollow needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body. ... Interventional Thyroid Ultrasound for thyroid cysts, and metastatic thyroid cancer lymph nodes The high frequency thyroid ultrasound,HFUS can be used to treat several gland conditions. ... Brain biopsy A biopsy (in Greek: bios = life and opsy = look/appearance) is a medical test involving the removal of cells or tissues for examination. ... Blood transfusion is the taking of blood or blood-based products from one individual and inserting them into the circulatory system of another. ... Hemolytic disease of the newborn, also known as HDN, is an alloimmune condition that develops in a fetus, when the IgG antibodies that have been produced by the mother and have passed through the placenta include ones which attack the red blood cells in the fetal circulation. ... Contrast-enhanced ultrasound (CEU) is the application of ultrasound contrast agents to traditional medical sonography. ...

Sonograph showing the image of a fetal head in the womb
Sonograph showing the image of a fetal head in the womb

Obstetrical ultrasound is commonly used during pregnancy to check on the development of the fetus. Image File history File linksMetadata Download high resolution version (1200x1600, 200 KB) Summary ultrasound machine showing a fetuses head Licensing File links The following pages link to this file: Medical ultrasonography Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize... Image File history File linksMetadata Download high resolution version (1200x1600, 200 KB) Summary ultrasound machine showing a fetuses head Licensing File links The following pages link to this file: Medical ultrasonography Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize... Obstetric sonogram of a fetus at 16 weeks. ... This article is about human pregnancy in biological females. ... For other uses, see Fetus (disambiguation). ...


In a pelvic sonogram, organs of the pelvic region are imaged. This includes the uterus and ovaries or urinary bladder. Men are sometimes given a pelvic sonogram to check on the health of their bladder and prostate. There are two methods of performing a pelvic sonography - externally or internally. The internal pelvic sonogram is performed either transvaginally (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.[1] This article is about female reproductive anatomy. ... // For ovary as part of plants see ovary (plants) An ovary is an egg-producing reproductive organ found in female organisms. ... This article is about the urinary bladder. ... The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ...


In abdominal sonography, the solid organs of the abdomen such as the pancreas, aorta, inferior vena cava, liver, gall bladder, bile ducts, kidneys, and spleen are imaged. Sound waves are blocked by gas in the bowel, therefore there are limited diagnostic capabilities in this area. The appendix can sometimes be seen when inflamed eg: appendicitis. The pancreas is a gland organ in the digestive and endocrine systems of vertebrates. ... The aorta (generally pronounced [eɪˈɔːtə] or ay-orta) is the largest artery in the human body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation. ... This article may be too technical for most readers to understand. ... For the bird, see Liver bird. ... The gallbladder (or cholecyst) is a pear-shaped organ that stores bile (or gall) until the body needs it for digestion. ... A bile duct is any of a number of long tube-like structures that carry bile. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... The spleen is an organ located in the abdomen, where it functions in the destruction of old red blood cells and holding a reservoir of blood. ... In human anatomy, the vermiform appendix (or appendix, pl. ... Appendicitis (or epityphlitis) is a condition characterized by inflammation of the appendix[1]. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy. ...


Therapeutic applications

Therapeutic applications use ultrasound to bring heat or agitation into the body. Therefore much higher energies are used than in diagnostic ultrasound. In many cases the range of frequencies used are also very different.

  • Ultrasound may be used to clean teeth in dental hygiene.
  • Ultrasound sources may be used to generate regional heating in biological tissue, e.g. in occupational therapy, physical therapy and cancer treatment.
  • Focused ultrasound may be used to generate highly localized heating to treat cysts and tumors (benign or malignant), This is known as Focused Ultrasound Surgery (FUS) or High Intensity Focused Ultrasound (HIFU). These procedures generally use lower frequencies than medical diagnostic ultrasound (from 250 kHz to 2000 kHz), but significantly higher energies. HIFU treatment is often guided by MRI.
  • Focused ultrasound may be used to break up kidney stones by lithotripsy.
  • Ultrasound may be used for cataract treatment by phacoemulsification.
  • Additional physiological effects of low-intensity ultrasound have recently been discovered, e.g. its ability to stimulate bone-growth and its potential to disrupt the blood-brain barrier for drug delivery.

A Dental hygienist attends to a patient A dental hygienist is a licensed dental auxiliary who specializes in preventive dental care, typically but not limited to focusing on techniques in oral hygiene . ... Occupational therapy refers to the use of meaningful occupation to assist people who have difficulty in achieving healthy and balanced life; and to enable an inclusive society so that all people can participate to their potential in daily occupations of life. ... Physical therapy (or physiotherapy[1]) is the provision of services to people and populations to develop, maintain and restore maximum movement and functional ability throughout the lifespan. ... Experimental cancer treatments are medical therapies intended or claimed to treat cancer (see also tumor) by improving on, supplementing or replacing conventional methods (surgery, chemotherapy, radiation, and immunotherapy). ... HIFU, or high intensity focused ultrasound, also referred to as Focused Ultrasound Surgery (FUS), is a term used describe a minimally or non-invasive method to deposit acoustic energy into tissue. ... HIFU, or high intensity focused ultrasound, also referred to as Focused Ultrasound Surgery (FUS), is a term used describe a minimally or non-invasive method to deposit acoustic energy into tissue. ... The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ... “Bladder stone” redirects here. ... A lithotriptor is a medical device used in the non-invasive treatment of kidney stones (urinary calculosis) and biliary calculi (stones in the gallbladder or in the liver). ... Human eye cross-sectional view, showing position of human lens. ... Phacoemulsification: Cataract surgery, by a temporal approach, using a phacoemulsification probe (in right hand) and chopper(in left hand), being done under operating microscope at a Navy medical center Phacoemulsification refers to modern cataract surgery in which the eyes internal lens is emulsified with an ultrasonic handpiece, and aspirated... The blood-brain barrier (BBB) is a membranic structure that acts primarily to protect the brain from chemicals in the blood, while still allowing essential metabolic function. ...

From sound to image

The creation of an image from sound is done in three steps - producing a sound wave, receiving echoes, and interpreting those echoes. This article is about compression waves. ... In audio signal processing and acoustics, an echo (plural echoes) is a reflection of sound, arriving at the listener some time after the direct sound. ...


Producing a sound wave

Medical Sonographic Scanner
Medical Sonographic Scanner

A sound wave is typically produced by a piezoelectric transducer encased in a probe. Strong, short electrical pulses from the ultrasound machine make the transducer ring at the desired frequency. The frequencies can be anywhere between 2 and 15 MHz. 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 machine. 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. Image File history File linksMetadata AlokaPhoto2006a. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ... A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ... Look up probe in Wiktionary, the free dictionary. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ...


Older technology transducers focus their beam with physical lenses. Newer technology transducers use phased array techniques to enable the sonographic machine to change the direction and depth of focus. Almost all piezoelectric transducers are made of ceramic. For the ultrasonic and medical imaging application, see phased array ultrasonics. ... This article is about ceramic materials. ...


Materials on the face of the transducer enable the sound to be transmitted efficiently into the body (usually seeming to be a rubbery coating, a form of impedance matching). In addition, a water-based gel is placed between the patient's skin and the probe. Impedance matching is the practice of attempting to make the output impedance of a source equal to the input impedance of the load to which it is ultimately connected, usually in order to maximize the power transfer and minimize reflections from the load. ...


The sound wave is partially reflected from the layers between different tissues. In detail, sound is reflected anywhere there are density changes in the body: e.g. blood cells in blood plasma, small structures in organs, etc. Some of the reflections return to the transducer.


Receiving the echoes

The return of the sound wave to the transducer results in the same process that it took to send the sound wave, except in reverse. The return sound wave vibrates the transducer, the transducer turns the vibrations into electrical pulses that travel to the ultrasonic scanner where they are processed and transformed into a digital image. A digital image is a representation of a two-dimensional image as a finite set of digital values, called picture elements or pixels. ...


Forming the image

The sonographic scanner must determine three things from each received echo:

  • The direction of the echo.
  • How strong the echo was.
  • How long it took the echo to be received from when the sound was transmitted.

Once the ultrasonic scanner determines these three things, it can locate which pixel in the image to light up and to what intensity.


Transforming the received signal into a digital image may be explained by using a blank spreadsheet as an analogy. We imagine our transducer is a long, flat transducer at the top of the sheet. We will send pulses down the 'columns' of our spreadsheet (A, B, C, etc.). We listen at each column for any return echoes. When we hear an echo, we 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, we have a greyscale image.


Sound in the body

Linear Array Transducer
Linear Array Transducer

Ultrasonography (sonography) uses a probe containing one or more acoustic transducers to send pulses of sound into a material. Whenever a sound wave encounters a material with a different density (acoustical impedance), part of the sound wave 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 see deeper. Image File history File linksMetadata UltrasoundProbe2006a. ... Night writing was a system of code that used symbols of twelve dots (2 wide and 6 high) designed by Charles Barbier in response to Napoleons demand for a code that soldiers could use to communicate silently and without light at night. ... A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ... In audio signal processing and acoustics, an echo (plural echoes) is a reflection of sound, arriving at the listener some time after the direct sound. ...


The frequencies used for medical imaging are generally in the range of 1 to 18 MHz. Higher frequencies have a correspondingly smaller wavelength, and can be used to make sonograms with smaller details. However, the attenuation of the sound wave is increased at higher frequencies, so in order to have better penetration of deeper tissues, a lower frequency (3-5 MHz) is used.


Seeing deep into the body with sonography is very difficult. Some acoustic energy is lost every time an echo is formed, but most of it (approximately textstyle 0.3 frac{mbox{dB}}{mbox{cm depth}cdotmbox{MHz}})is lost from acoustic absorption.


The speed of sound is different in 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 m/s. An effect of this assumption is that in a real body with non-uniform tissues, the beam become somewhat de-focused and image resolution is reduced. The acoustic impedance Z (or sound impedance) is a frequency f dependent parameter and is very useful, for example, for describing the behaviour of musical wind instruments. ...


To generate a 2D-image, the ultrasonic beam is swept. A transducer may be swept mechanically by rotating or swinging. Or a 1D phased array transducer may be use to sweep the beam electronically. The received data is processed and used to construct the image. The image is then a 2D representation of the slice into the body. For the ultrasonic and medical imaging application, see phased array ultrasonics. ...


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


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. A source of waves moving to the left. ...


Modes of sonography

Four different modes of ultrasound are used in medical imaging[2]. These are:

  • A-mode: A-mode is the simplest type of ultrasound. A single transducer scans a line through the body with the echoes plotted on screen as a function of depth. Therapeutic ultrasound aimed at a specific tumor or calculus is also A-mode, to allow for pinpoint accurate focus of the destructive wave energy.
  • B-mode: In B-mode ultrasound, a linear array of transducers simultaneously scans a plane through the body that can be viewed as a two-dimensional image on screen.
  • M-mode: M stands for motion. In m-mode a rapid sequence of B-mode scans whose images follow each other in sequence on screen enables doctors to see and measure range of motion, as the organ boundaries that produce reflections move relative to the probe.
  • Doppler mode: This mode makes use of the Doppler effect.

Doppler sonography

Spectral Doppler of Common Carotid Artery
Spectral Doppler of Common Carotid Artery
Colour Doppler of Common Carotid Artery
Colour Doppler of Common Carotid Artery

Sonography can be enhanced with Doppler measurements, which employ the Doppler effect to assess whether structures (usually blood) are moving towards or away from the probe, and its relative velocity. By calculating the frequency shift of a particular sample volume, for example a jet of blood flow over a heart valve, its speed and direction can be determined and visualised. This is particularly useful in cardiovascular studies (sonography of the vasculature system and heart) and essential in many areas such as determining reverse blood flow in the liver vasculature in portal hypertension. The Doppler information is displayed graphically using spectral Doppler, or as an image using color Doppler (directional Doppler) or power Doppler (non directional Doppler). This Doppler shift falls in the audible range and is often presented audibly using stereo speakers: this produces a very distinctive, although synthetic, pulsing sound. Image File history File linksMetadata SpectralDopplerA.jpg Summary Medical spectral Doppler of common carotid artery By Daniel W. Rickey 2006 Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata ColourDopplerA.jpg Summary Medical colour Doppler of common carotid artery By Daniel W. Rickey 2006 Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A source of waves moving to the left. ... In medicine, portal hypertension is hypertension (high blood pressure) in the portal vein and its branches. ...


Strictly speaking, most modern sonographic machines do not use the Doppler effect to measure velocity, as they rely on pulsed wave Doppler (PW). Pulsed wave machines transmit pulses of ultrasound, and then switch to receive mode. As such, the reflected pulse that they receive is not subject to a frequency shift, as the insonation is not continuous. However, by making several measurements, the phase change in subsequent measurements can be used to obtain the frequency shift (since frequency is the rate of change of phase). To obtain the phase shift between the received and transmitted signals, one of two algorithms is typically used: the Kasai algorithm or cross-correlation. Older machines, that use continuous wave (CW) Doppler, exhibit the Doppler effect as described above. To do this, they must have separate transmission and reception transducers. The major drawback of CW machines, is that no distance information can be obtained (this is the major advantage of PW systems - the time between the transmitted and received pulses can be converted into a distance with knowledge of the speed of sound). Pulse-Doppler is a radar system capable of not only detecting target location (bearing, range, and altitude), but also measuring its radial velocity (range-rate). ... The autocorrelation technique is a method for estimating the dominating frequency in a complex signal, as well as its variance. ... In statistics, the term cross-correlation is sometimes used to refer to the covariance cov(X, Y) between two random vectors X and Y, in order to distinguish that concept from the covariance of a random vector X, which is understood to be the matrix of covariances between the scalar...


In the sonographic community (although not in the signal processing community), the terminology "Doppler" ultrasound, has been accepted to apply to both PW and CW Doppler systems despite the different mechanisms by which the velocity is measured.


Microbubbles

The use of microbubble contrast media in medical sonography to improve ultrasound signal backscatter is known as contrast-enhanced ultrasound. This technique is currently used in echocardiography, and may have future applications in molecular imaging and drug delivery. Backscatter is the reflection of waves, particles, or signals back to the direction they came from. ... Contrast-enhanced ultrasound (CEU) is the application of ultrasound contrast agents to traditional medical sonography. ... An echocardiogram. ...


Strengths of sonography

  • It images muscle and soft tissue very well and is particularly useful for delineating the interfaces between solid and fluid-filled spaces.
  • It renders "live" images, where the operator can dynamically select the most useful section for diagnosing and documenting changes, often enabling rapid diagnoses.
  • It shows the structure of organs.
  • It has no known long-term side effects and rarely causes any discomfort to the patient.
  • Equipment is widely available and comparatively flexible.
  • Small, easily carried scanners are available; examinations can be performed at the bedside.
  • Relatively inexpensive compared to other modes of investigation (e.g. computed X-ray tomography, DEXA or magnetic resonance imaging).

For other uses of Muscles, see Muscles (disambiguation). ... In medicine, the term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body. ... negron305 Cat scan redirects here. ... Dual energy X-ray absorptiometry (DXA, previously DEXA) is a means of measuring bone mineral density (BMD). ... MRI redirects here. ...

Weaknesses of ultrasonic imaging

  • Sonographic devices have trouble penetrating bone. For example, sonography of the adult brain is very limited.
  • Sonography performs very poorly when there is a 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, and lung imaging is not possible (apart from demarcating pleural effusions).
  • Even in the absence of bone or air, the depth penetration of ultrasound is limited, making it difficult to image structures deep in the body, especially in obese patients.
  • The method is operator-dependent. A high level of 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 MR. Once an image has been acquired there is no exact way to tell which part of the body was imaged.

This article is about the skeletal organs. ... In electrical engineering, Impedance is a measure of opposition to a sinusoidal electric current. ... The pancreas is a gland organ in the digestive and endocrine systems of vertebrates. ...

Risks and side-effects

Ultrasonography is generally considered a "safe" imaging modality.[citation needed] However slight detrimental effects have been occasionally observed (see below). Diagnostic ultrasound studies of the fetus are generally considered to be safe during pregnancy. 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 achievable" or ALARA principle. ALARA Alara king of Nubia The unifier of Kush and grandfather of king Taharqa ...


The promotion, selling, or leasing of ultrasound equipment for making "keepsake fetal videos" is considered by the US Food and Drug Administration to be an unapproved use of a medical device. Use of a diagnostic ultrasound system for these purposes, without a physician’s order, may be in violation of state laws or regulations.


Studies on the safety of ultrasound

  • A study at the Yale Medical School found a correlation between prolonged and frequent use of ultrasound and abnormal neuronal migration in mice.[3]
  • A study published in 2001 by a team working at the Karolinska Institute in Stockholm found a correlation between the number of scans received by male fetuses and subsequent left-handedness. [4]
  • A meta-analysis of several ultrasonography studies found no statistically significant harmful effects from ultrasonography, but mentioned that there was a lack of data on long-term substantive outcomes such as neurodevelopment.[5]

The Yale School of Medicine is a private medical school located in New Haven, Connecticut. ... The Karolinska Institute or Karolinska institutet is a medical university in Stockholm, Sweden. ...

Regulation

Diagnostic sonography is regulated in the USA by the FDA, and world-wide by other national regulatory agencies. The FDA limits acoustic output using several metrics. Generally other regulatory agencies around the world accept the FDA-established guidelines.


The primary regulated metrics are MI (Mechanical Index) a metric associated with the cavitation bio-effect, and TI (Thermal Index) a metric associated with the tissue heating bio-effect. The FDA requires that the machine not exceed limits that they have established. This requires self-regulation on the part of the manufacturer in terms of the calibration of the machine. The established limits are reasonably conservative so as to maintain diagnostic ultrasound as a safe imaging modality.[citation needed]


History

United States

Ultrasonic energy was first applied to the human body for medical purposes by Dr. George Ludwig at the Naval Medical Research Institute, Bethesda, Maryland in the late 1940s.[6][7] George Döring Ludwig, M.D., was an American professor of medicine and medical researcher noted for developing the first application of ultrasonic energy to the human body for medical purposes, at the Naval Medical Research Institute, Bethesda, Maryland, in the late 1940s. ...


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.[8]


Sweden

Medical ultrasonography was used 1953 at Lund University by cardiologist Inge Edler and Carl Hellmuth Hertz, the son of Gustav Ludwig Hertz, who was a graduate student at the department of nuclear physics. January 7 - President Harry S. Truman announces the United States has developed a hydrogen bomb. ... Lund University (Swedish: ), located in Lund in southernmost Sweden, is one of Swedens most prestigious universities[2] and Scandinavias largest institution for education and research[3], frequently ranked among the worlds top 100 universities[4][5]. The university was founded in 1666 and is the second oldest... Cardiology is the branch of medicine pertaining to the heart. ... Carl Hellmuth Hertz (1920-1990) was the son of Gustav Ludwig Hertz. ... Gustav Ludwig Hertz (July 22, 1887, Hamburg – October 30, 1975, Berlin) was a German physicist, and a nephew of Heinrich Rudolf Hertz. ... Nuclear physics is the branch of physics concerned with the nucleus of the atom. ...


Edler had asked Hertz if it was possible to use radar to look into the body, but Hertz said this was impossible. However, he said, it might be possible to use ultrasonography. Hertz was familiar with using ultrasonic reflectoscopes for nondestructive materials testing, and together they developed the idea of using this method in medicine. For other uses, see Radar (disambiguation). ... // Nondestructive testing (also called NDT, nondestructive evaluation, NDE, and nondestructive inspection, NDI) is testing that does not destroy the test object. ...


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 used to generate an echo-encephalogram (ultrasonic probe of the brain). Edler and Hertz published their findings in 1954. is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... January 7 - President Harry S. Truman announces the United States has developed a hydrogen bomb. ... Kockums in Malmö, 1970 Foto: PÃ¥l-Nils Nilsson. ... Motto: FrÃ¥n arbetarstad till kunskapsstad (eng: From industrial city to knowledge city) Location of Malmö in northern Europe Coordinates: , Country  Sweden Municipality Malmö Municipality County SkÃ¥ne County Province Scania (SkÃ¥ne) Charter 13th century Government  - Mayor Illmar Reepalu Area  - City 335. ... is the 350th day of the year (351st in leap years) in the Gregorian calendar. ... Human brain In animals, the brain (enkephale) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ...


Scotland

Parallel developments in Glasgow, Scotland (coincidentally also a major shipbuilding centre) by Professor Ian Donald and colleagues at the Glasgow Royal Maternity Hospital (GRMH) led to the first diagnostic applications of the technique. 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 Babcock & Wilcox at Renfrew, where he used their industrial ultrasound equipment to conduct experiments on various morbid anatomical specimens and assess their ultrasonic characteristics. Together with the medical physicist Tom Brown and fellow obstetrician Dr John MacVicar, Donald refined the equipment to enable differentiation of pathology in live volunteer patients. These findings were reported in The Lancet on 7th June 1958 as "Investigation of Abdominal Masses by Pulsed Ultrasound" - possibly one of the most important papers ever published in the field of diagnostic medical imaging. For other uses, see Glasgow (disambiguation). ... This article is about the country. ... Professor Ian Donald (born December 1910 - died June 19, 1987) was a Scottish doctor who pioneered the use of diagnostic ultrasound in medicine. ... Glasgow Royal Maternity Hospital was founded as the Glasgow Lying-in Hospital and Dispensary in 1834 in Greyfriars Wynd. ... Obstetrics (from the Latin obstare, to stand by) is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth). ... Renfrew (Rinn Friù in Scottish Gaelic) is a small town, located six miles west of Glasgow on the west coast of Scotland. ... The Lancet is one of the oldest and most respected peer-reviewed medical journals in the world, published weekly by Elsevier, part of Reed Elsevier. ... Medical imaging designates the ensemble of techniques and processes used to create images of the human body (or parts thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). ...


At GRMH, Professor Donald and Dr James Willocks then refined their techniques to obstetric applications including fetal head measurement to assess the size and growth of the foetus. With the opening of the new Queen Mother's Hospital on Yorkhill in 1964, it became possible to improve these methods even further. Dr Stuart Campbell's pioneering work on fetal cephalometry led to it acquiring long-term status as the definitive method of study of fetal 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. Yorkhill is a district in the Scottish city of Glasgow. ...


See also

4D Ultrasound (also known as 3D/4D Ultrasound) is the most advanced technology used by sonographers during pregnancy to evaluate the unborn fetus. ... This article or section does not cite its references or sources. ...

References

  • Donald I, MacVicar J, Brown TG. Investigation of abdominal masses by pulsed ultrasound. Lancet 1958;1(7032):1188-95. PMID 13550965
  • Edler I, Hertz CH. The use of ultrasonic reflectoscope for the continuous recording of movements of heart walls. Kungl Fzsiogr Sallsk i Lund Forhandl. 1954;24:5. Reproduced in Clin Physiol Funct Imaging 2004;24:118-36. PMID 15165281.
  • S. A. Kana (2003). Introduction to physics in modern medicine. Tsylor & Francis. ISBN 0-415-30171-8. 
  • C. Kasai et al. Real-time two-dimensional blood flow imaging using an autocorrelation technique. IEEE Transactions on Sonics and Ultrasonics 1985:458-464.
  • Ohanyido FO,. Basic Sonology for Doctors in Low Income Settings. Healthquest 2005;3:23.
  • Bushberg JT (2002). The essential physics of medical imaging. Lippincott Williams & Wilkins. ISBN 0-683-30118-7. 
  1. ^ Sonography of the female pelvic floor Clinical indications and techniques
  2. ^ The Gale Encyclopedia of Medicine, 2nd Edition Volume 1 A-B. Page no.4
  3. ^ Ang ES Jr, Gluncic V, Duque A, Schafer ME, Rakic P (2006). "Prenatal exposure to ultrasound waves impacts neuronal migration in mice". Proc Natl Acad Sci U S A 103 (34): 12903–10. PMID 16901978. 
  4. ^ Kieler H, Cnattingius S, Haglund B, Palmgren J, Axelsson O (2001). "Sinistrality--a side-effect of prenatal sonography: a comparative study of young men". Epidemiology (Cambridge, Mass.) 12 (6): 618-23. PMID 11679787. 
  5. ^ Bricker L, Garcia J, Henderson J, et al (2000). "Ultrasound screening in pregnancy: a systematic review of the clinical effectiveness, cost-effectiveness and women's views". Health technology assessment (Winchester, England) 4 (16): i-vi, 1-193. PMID 11070816. 
  6. ^ History of the AIUM. Retrieved on November 15, 2005.
  7. ^ The History of Ultrasound: A collection of recollections, articles, interviews and images. www.obgyn.net. Retrieved on 2006-05-11.
  8. ^ Doppler Ultrasound History. www.obgyn.net. Retrieved on 2006-05-11.

The Lancet is one of the oldest and most respected peer-reviewed medical journals in the world, published weekly by Elsevier, part of Reed Elsevier. ... is the 319th day of the year (320th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 131st day of the year (132nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 131st day of the year (132nd in leap years) in the Gregorian calendar. ...

External links


  Results from FactBites:
 
Medical ultrasonography - Wikipedia, the free encyclopedia (2791 words)
Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structure and any pathological lesions, making them useful for scanning the organs.
In medical ultrasonography, a sound wave is typically produced by creating short, strong pulses of sound from a phased array of piezoelectric transducers (usually a type of ceramic).
Medical ultrasonography was used 1953 at Lund University by cardiologist Inge Edler and Carl Hellmuth Hertz, the son of Gustav Ludwig Hertz, who was a graduate student at the department of nuclear physics.
Medical imaging - Wikipedia, the free encyclopedia (1852 words)
Medical imaging is the process by which physicians evaluate an area of the subject's body that is not externally visible (this may be termed clinical imaging), and could therefore involve any medical discipline, and scientists researching into new methods of creating these images.
The medical specialist directing medical imaging is a radiologist, and the medical aspects are known as radiology.
Medical ultrasonography uses high frequency sound waves of between 2.0 to 10.0 megahertz that are reflected by tissue to varying degrees to produce a 2D image, traditionally on a TV monitor.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m