{"id":272,"date":"2024-01-28T22:12:26","date_gmt":"2024-01-28T22:12:26","guid":{"rendered":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/?post_type=front-matter&p=272"},"modified":"2024-03-10T13:51:11","modified_gmt":"2024-03-10T13:51:11","slug":"list-of-definitions","status":"publish","type":"front-matter","link":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/front-matter\/list-of-definitions\/","title":{"raw":"List of Definitions","rendered":"List of Definitions"},"content":{"raw":"
    \r\n \t
  1. a<\/span>bsorption<\/span><\/strong>\u2014The attenuation process involving ultrasound energy lost to tissue in the form of heat.<\/li>\r\n \t
  2. a<\/span>coustic<\/span><\/strong>\u2014Having to do with sound.<\/li>\r\n \t
  3. a<\/span>mniotic <\/span>f<\/span>luid<\/span><\/strong>\u2014A liquid that surrounds the fetus in the uterus.<\/li>\r\n \t
  4. a<\/span>mplifier<\/span><\/strong>\u2014An electronic device that enhances a signal, making the output signal stronger than the input signal.<\/li>\r\n \t
  5. a<\/span>mplitude<\/span><\/strong> (of a wave)\u2014Maximum displacement of a point on a wave or vibrating object relative to equilibrium position.<\/li>\r\n \t
  6. a<\/span>mplitude <\/span>m<\/span>ode<\/span><\/strong>\u2014A one-dimensional display mode used in diagnostic sonography in which the echo depth is on the horizontal axis and the amplitude is on the vertical axis.<\/li>\r\n \t
  7. a<\/span>nechoic<\/span><\/strong>\u2014Areas that appear dark on ultrasound because they do not reflect sound waves back to the transducer.<\/li>\r\n \t
  8. a<\/span>nesthesiology<\/span><\/strong>\u2014A branch of medical science dealing with anesthesia and anesthetics.<\/li>\r\n \t
  9. a<\/span>neurysm<\/span><\/strong>\u2014An unexpected balloon-like bulge in an artery. If it bursts or leaks, it can cause dangerous bleeding or even death. According to the National Institutes<\/ins> of Health, about 13,000 people die yearly in the United States from abdominal aortic aneurysms.<\/li>\r\n \t
  10. a<\/span>ngle of <\/span>i<\/span>nsonation<\/span><\/strong>\u2014Within sonography, the angle that the ultrasound beam makes relative to the tissue or organ of interest.<\/li>\r\n \t
  11. a<\/span>nisotropy<\/span><\/strong>\u2014An artifact on ultrasound images caused by variations in the angles of insonation produced by varying properties of tissue.<\/li>\r\n \t
  12. a<\/span>nterior<\/span><\/strong>\u2014Relating to the front (for example, the kneecap is located on the anterior side of the leg).<\/li>\r\n \t
  13. artifact<\/strong>\u2014A false portrayal of image anatomy usually characterized by an inappropriate brightness, shape, size, or position<\/li>\r\n \t
  14. \u201cAs Low As Reasonably Achievable<\/strong>\u201d<\/span>\u2014Refers to responsibly exposing the patient to the minimum energy possible to obtain appropriate diagnostic information.<\/li>\r\n \t
  15. a<\/span>therosclerosis<\/span><\/strong>\u2014A disease in which plaque (buildup of fat, cholesterol, calcium, or other products) builds up, subsequently narrowing the arteries and thus limiting the flow of oxygenated blood to organs and other parts of the body. This condition can lead to heart attack, stroke, or even death.<\/li>\r\n \t
  16. a<\/span>ttenuation<\/span><\/strong>\u2014The decrease in the energy and amplitude of a wave as it passes through a medium due to the effects of absorption, reflection, and scattering. As the beam passes through tissue, its intensity decreases over time.<\/li>\r\n \t
  17. a<\/span>xial <\/span>r<\/span>esolution<\/span><\/strong>\u2014The minimum distance between two reflectors along the sound path that can be resolved to produce separate sound waves.<\/li>\r\n \t
  18. Baker\u2019s <\/span>c<\/span>yst<\/span><\/strong>\u2014A fluid-filled growth behind the knee.<\/li>\r\n \t
  19. b<\/span>ioeffects of <\/span>u<\/span>ltrasound<\/span><\/strong>\u2014Within sonography, refers to the adverse effects of ultrasound beams on tissues (including soft tissue, body fluids, and bone).<\/li>\r\n \t
  20. b<\/span>iohazard<\/span><\/strong>\u2014Biological organisms or substances that can threaten human health.<\/li>\r\n \t
  21. b<\/span>iopsy<\/span><\/strong>\u2014A procedure medical professionals use to remove a piece of tissue or a sample of cells from the body for laboratory analysis.<\/li>\r\n \t
  22. b<\/span>lood <\/span>p<\/span>ressure<\/span><\/strong>\u2014Pressure created by blood against the walls of the arteries as the heart pumps it through the body.<\/li>\r\n \t
  23. b<\/span>rightness <\/span>m<\/span>ode<\/span><\/strong>\u2014A two-dimensional display mode used in diagnostic sonography in which the image is composed of bright dots representing the ultrasound echoes. The brightness of each dot is determined by the amplitude of the returned echo signal.<\/li>\r\n \t
  24. c<\/span>alcification<\/span><\/strong>\u2014A process of calcium buildup in body tissue that causes the tissue to harden.<\/li>\r\n \t
  25. c<\/span>ardiac <\/span>a<\/span>rrest<\/span><\/strong>\u2014An abrupt inability of the heart to contract and generate a pulse and adequate blood flow leading to starvation of blood in the brain and other organs.<\/li>\r\n \t
  26. c<\/span>ardiology<\/span><\/strong>\u2014A medical specialty that involves finding, treating, and preventing diseases of the heart and blood vessels.<\/li>\r\n \t
  27. c<\/span>ardiopulmonary <\/span>r<\/span>esuscitation<\/span><\/strong>\u2014A lifesaving procedure performed by combining rescue breathing (mouth-to-mouth) and chest compressions to temporarily pump enough blood to the brain when the heart stops beating and until specialized treatment is available.<\/li>\r\n \t
  28. c<\/span>audal<\/span><\/strong>\u2014See <\/em>i<\/em>nferior<\/em><\/span>.<\/li>\r\n \t
  29. c<\/span>avitation<\/span><\/strong>\u2014Production and dynamics of bubbles caused by sound waves. The bubbles oscillate inside the tissue due to the rapidly changing acoustic pressure.<\/li>\r\n \t
  30. c<\/span>ircle of Willis<\/span><\/strong>\u2014A complete ring of arteries at the base of the brain that is formed by the cerebral and communicating arteries.<\/li>\r\n \t
  31. c<\/span>olor Doppler <\/span>d<\/span>isplay<\/span><\/strong>\u2014Two-dimensional, real-time Doppler shift information superimposed on a real-time, grayscale, anatomic cross-sectional image. Flow directions display different colors.<\/li>\r\n \t
  32. c<\/span>omet <\/span>t<\/span>ail<\/span><\/strong>\u2014A series of closely spaced reverberation echoes.<\/li>\r\n \t
  33. c<\/span>ompression<\/span><\/strong>\u2014A region in a longitudinal wave (like sound waves) where the particles are closest together.<\/li>\r\n \t
  34. c<\/span>omputerized <\/span>t<\/span>omography<\/span><\/strong>\u2014An imaging technique that combines a series of X-ray images taken from different angles around the body.<\/li>\r\n \t
  35. c<\/span>ontinuous <\/span>w<\/span>ave Doppler<\/span><\/strong>\u2014An imaging mode in which the transducer uses two crystals: one for continuous transmission and the other for reception of ultrasound signals. This technique allows measurements of high-velocity flows, especially in the heart.<\/li>\r\n \t
  36. c<\/span>ontrast <\/span>r<\/span>esolution<\/span><\/strong>\u2014The ability to distinguish echoes of slightly different intensities on a grayscale display.<\/li>\r\n \t
  37. Coronavirus <\/span>d<\/span>isease 2019<\/span><\/strong>\u2014An infectious disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus that was discovered in 2019.<\/li>\r\n \t
  38. c<\/span>oupling <\/span>m<\/span>edium<\/span><\/strong>\u2014Within sonography, a gel that is applied between the tissue surface, typically skin, and the ultrasound transducer to displace air at the boundary surface and transmit sound waves through the skin.<\/li>\r\n \t
  39. c<\/span>ranial<\/span><\/strong>\u2014See <\/em>s<\/em>uperior<\/em><\/span>.<\/li>\r\n \t
  40. c<\/span>ritical <\/span>c<\/span>are<\/span><\/strong>\u2014A branch of medicine focused on the care of people with life-threatening or critical injuries and illnesses requiring more specialized care.<\/li>\r\n \t
  41. c<\/span>ross<\/span> section<\/span><\/strong>\u2014A transverse cut through a structure or tissue.<\/li>\r\n \t
  42. c<\/span>ycle<\/span><\/strong>\u2014Within sonography, represents the combination of one rarefaction and one compression of a sound wave.<\/li>\r\n \t
  43. c<\/span>yst<\/span><\/strong>\u2014An abnormal sac or cavity in the body containing fluid or semisolid material.<\/li>\r\n \t
  44. d<\/span>eep<\/span><\/strong>\u2014Position that is closer to the interior center of the body.<\/li>\r\n \t
  45. d<\/span>ermatology<\/span><\/strong>\u2014A branch of medicine dealing with the skin, its structure, and its diseases.<\/li>\r\n \t
  46. d<\/span>iastole<\/span><\/strong>\u2014A phase in the cardiac cycle during which the heart relaxes and allows blood to refill.<\/li>\r\n \t
  47. d<\/span>iffraction<\/span><\/strong>\u2014Refers to the bending of an ultrasound beam when it passes around an edge or through a narrow opening.<\/li>\r\n \t
  48. d<\/span>istal<\/span><\/strong>\u2014Away from or farthest from the trunk or the point or origin of a part (for example, the hand is located at the distal end of the forearm).<\/li>\r\n \t
  49. Doppler <\/span>a<\/span>ngle<\/span><\/strong>\u2014The angle between the sound beam and the flow direction.<\/li>\r\n \t
  50. Doppler <\/span>e<\/span>ffect<\/span><\/strong>\u2014A shift in frequency received by the transducer secondary to the sound wave reflecting off a moving object, such as a moving collection of red blood cells. Within sonography, this phenomenon is used to measure the flow velocity of the blood during echocardiography.<\/li>\r\n \t
  51. Doppler <\/span>e<\/span>quation<\/span><\/strong>\u2014Relates the various parameters that affect the Doppler shift frequency. The equation is<\/li>\r\n<\/ol>\r\n

    \"Equation<\/p>\r\n

    where f<\/em>s<\/em><\/sub><\/span> is the Doppler shift frequency, v<\/em><\/span> is the receiver (target) velocity, \u03b8<\/em><\/span> is the Doppler angle, and c<\/em><\/span> is the speed of sound in tissue, which is 1540 m\/s.<\/p>\r\n\r\n

      \r\n \t
    1. Doppler <\/span>s<\/span>hift <\/span>f<\/span>requency<\/span><\/strong>\u2014The amount of change in frequency caused by the Doppler effect.<\/li>\r\n \t
    2. d<\/span>orsal<\/span><\/strong>\u2014See <\/em>p<\/em>osterior<\/em><\/span>.<\/li>\r\n \t
    3. d<\/span>uplex <\/span>i<\/span>maging<\/span><\/strong>\u2014A process of combining two-dimensional real-time imaging with Doppler signal processing.<\/li>\r\n \t
    4. e<\/span>cho<\/span><\/strong>\u2014Within sonography, a reflected ultrasound signal. The signals are converted by the processor into gray dots on the ultrasound display.<\/li>\r\n \t
    5. e<\/span>chocardiography<\/span><\/strong>\u2014A diagnostic ultrasound test used to evaluate cardiac anatomy and physiology.<\/li>\r\n \t
    6. e<\/span>ddies<\/span><\/strong>\u2014Regions of circular flow patterns present within turbulent flow patterns.<\/li>\r\n \t
    7. e<\/span>dema<\/span><\/strong>\u2014Swelling caused by too much fluid trapped in the body\u2019s tissues.<\/li>\r\n \t
    8. e<\/span>ffusion<\/span><\/strong>\u2014An excessive accumulation of fluid in a region or a structure.<\/li>\r\n \t
    9. e<\/span>mergency <\/span>m<\/span>edicine<\/span><\/strong>\u2014A medical specialty involving care for patients with acute illnesses or injuries requiring immediate medical attention.<\/li>\r\n \t
    10. e<\/span>mphysema<\/span><\/strong>\u2014A lung condition that causes shortness of breath due to damaged air sacs in the lungs.<\/li>\r\n \t
    11. f<\/span>ascia<\/span><\/strong>\u2014A thin casing of connective tissue that surrounds and holds every organ, blood vessel, bone, nerve fiber, and muscle in place.<\/li>\r\n \t
    12. f<\/span>ibrosis<\/span><\/strong>\u2014Scarring and hardening of tissues and organs.<\/li>\r\n \t
    13. f<\/span>lexion<\/span><\/strong>\u2014Bending of an arm or leg. It\u2019s a physical position that decreases the angle between the bones of the limb at a joint.<\/li>\r\n \t
    14. f<\/span>ocal <\/span>l<\/span>ength<\/span><\/strong>\u2014The distance from the scanning face of a transducer to the focus.<\/li>\r\n \t
    15. f<\/span>ocus<\/span><\/strong>\u2014A narrow point in the cross section of the ultrasound beam. To improve the resolution at a given depth, the transducer must be focused in order to narrow the beam width. This is performed by varying the number of transmitting and receiving elements and delaying the signal once received.<\/li>\r\n \t
    16. f<\/span>rame<\/span><\/strong>\u2014A single image produced by one complete scan of the sound beam.<\/li>\r\n \t
    17. f<\/span>rame <\/span>r<\/span>ate<\/span><\/strong>\u2014The number of frames of echo information stored each second.<\/li>\r\n \t
    18. f<\/span>requency<\/span><\/strong>\u2014The number of cycles per second. In diagnostic ultrasound, it is usually demonstrated in megahertz.<\/li>\r\n \t
    19. f<\/span>riction<\/span><\/strong>\u2014Within sonography, the force that resists the relative motion between blood and the cardiovascular walls.<\/li>\r\n \t
    20. g<\/span>ain<\/span><\/strong>\u2014The degree of amplification of the returning echo.<\/li>\r\n \t
    21. g<\/span>ate<\/span><\/strong>\u2014A device that allows only echoes from selected depths to pass.<\/li>\r\n \t
    22. g<\/span>estation<\/span><\/strong>\u2014The process or period of development inside the womb between conception and birth.<\/li>\r\n \t
    23. g<\/span>rating<\/span><\/strong>\u2014The process in which an input ultrasound beam splits into multiple beams after passing tissue, resulting in the formation of side lobe artifacts.<\/li>\r\n \t
    24. g<\/span>rayscale<\/span><\/strong>\u2014The range of brightness between white and black. The dark color indicates the total absence of reflected light, and the bright represents reflected light.<\/li>\r\n \t
    25. g<\/span>ynecology<\/span><\/strong>\u2014A specialty of the female reproductive system, including the diagnosis and treatment of conditions, disorders, and diseases.<\/li>\r\n \t
    26. h<\/span>armonics<\/span><\/strong>\u2014Frequencies that are even and odd multiples of one another.<\/li>\r\n \t
    27. h<\/span>ertz<\/span><\/strong>\u2014Unit of frequency, one cycle per second.<\/li>\r\n \t
    28. h<\/span>ydrocephalus<\/span><\/strong>\u2014A neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles or cavities deep within the brain.<\/li>\r\n \t
    29. h<\/span>ydronephrosis<\/span><\/strong>\u2014Swelling of a kidney due to urine failing to drain properly from the kidney to the bladder.<\/li>\r\n \t
    30. h<\/span>yperechoic<\/span><\/strong>\u2014Areas on the image with more reflected echoes that appear brighter than the surrounding tissue.<\/li>\r\n \t
    31. h<\/span>ypertension<\/span><\/strong>\u2014High systolic and\/or diastolic blood pressure.<\/li>\r\n \t
    32. h<\/span>ypoechoic<\/span><\/strong>\u2014Areas on the image with fewer reflected echoes that appear darker than the surrounding tissue.<\/li>\r\n \t
    33. h<\/span>ysterectomy<\/span><\/strong>\u2014A surgical removal of the uterus.<\/li>\r\n \t
    34. i<\/span>mpedance<\/span><\/strong>\u2014The resistance to the propagation of ultrasound waves through tissues. It is determined by the density of the tissue and the sound propagation speed.<\/li>\r\n \t
    35. i<\/span>nertia<\/span><\/strong>\u2014Resistance to change in the state of either rest or motion or the tendency to keep moving in a straight line at a constant velocity.<\/li>\r\n \t
    36. i<\/span>nferior<\/span><\/strong>\u2014Away from the head; lower (for example, the foot is part of the inferior extremity).<\/li>\r\n \t
    37. i<\/span>ntensity<\/span><\/strong>\u2014The power per unit area,<\/ins> usually expressed in milliwatts per square centimeter in sonographic discussions. It is the ultrasound power transferred per unit area.<\/li>\r\n \t
    38. i<\/span>nternal <\/span>m<\/span>edicine<\/span><\/strong>\u2014A branch of medicine that deals with long-term care involving common and complex illnesses such as the diagnosis and treatment of cancer, infections, and diseases affecting the heart, blood, kidneys, joints, and digestive, respiratory, and vascular systems in adolescents, adults, and elderly individuals.<\/li>\r\n \t
    39. i<\/span>ntima-<\/span>m<\/span>edia <\/span>t<\/span>hickness <\/span>a<\/span>nalysis<\/span><\/strong>\u2014An ultrasound measurement of the thickness of the two inner layers of the carotid arteries\u2014the intima and media. Abnormal thickening of the arterial walls of the carotid arteries indicates a high risk for heart attack or stroke.<\/li>\r\n \t
    40. i<\/span>ntrarenal <\/span>p<\/span>erfusion<\/span><\/strong>\u2014Fluid injection into the renal blood vessels to or from the kidneys.<\/li>\r\n \t
    41. l<\/span>aminar <\/span>f<\/span>low<\/span><\/strong>\u2014Demonstration of fluid moving in an organized direction as if it were made up of layers that glide over one another.<\/li>\r\n \t
    42. l<\/span>ateral<\/span><\/strong>\u2014Away from the midline of the body (for example, the little toe is located at the lateral side of the foot).<\/li>\r\n \t
    43. l<\/span>ateral <\/span>r<\/span>esolution<\/span><\/strong>\u2014Refers to reflectors that lie perpendicular to the axis of the ultrasound beam. The resolution is related to the beam width; that is, the wider the beam, the poorer the lateral resolution. An ultrasound beam is the narrowest at its focal length, and this is where the lateral resolution will be the best.<\/li>\r\n \t
    44. l<\/span>ateral <\/span>r<\/span>otation<\/span><\/strong>\u2014Lateral rotation of the upper limb at the shoulder or lower limb at the hip involves turning the anterior surface of the limb away from the midline of the body. Lateral rotation is also referred to as exterior rotation.<\/li>\r\n \t
    45. l<\/span>inear <\/span>a<\/span>rray<\/span><\/strong>\u2014An array made of rectangular elements arranged in a line.<\/li>\r\n \t
    46. l<\/span>inear <\/span>p<\/span>hased <\/span>a<\/span>rray<\/span><\/strong>\u2014A linear array that operates by applying voltage pulses to all elements with small time differences to direct sound waves out in various directions.<\/li>\r\n \t
    47. l<\/span>inear <\/span>s<\/span>equenced <\/span>a<\/span>rray<\/span><\/strong>\u2014A linear array that operates by applying voltage pulses to groups of elements in a sequence.<\/li>\r\n \t
    48. Lister\u2019s tubercle<\/span><\/strong>\u2014A bony prominence located at the distal end of the radius.<\/li>\r\n \t
    49. l<\/span>umen<\/span><\/strong>\u2014An inner open space or cavity of a tubular structure, as of a blood vessel or an intestine.<\/li>\r\n \t
    50. m<\/span>aternity<\/span><\/strong>\u2014The period during and immediately after pregnancy.<\/li>\r\n \t
    51. m<\/span>echanical index<\/span><\/strong>\u2014A value used to estimate the cavitation effect during exposure to ultrasound energy.<\/li>\r\n \t
    52. m<\/span>edial<\/span><\/strong>\u2014Relating to the midline of the body (for example, the middle toe is located at the medial side of the foot).<\/li>\r\n \t
    53. m<\/span>edial <\/span>r<\/span>otation<\/span><\/strong>\u2014Medial rotation of the upper limb at the shoulder or lower limb at the hip involves turning the anterior surface of the limb toward the midline of the body. Medial rotation is also referred to as internal rotation.<\/li>\r\n \t
    54. m<\/span>irroring<\/span><\/strong>\u2014An artifact on a spectral display caused by an inability to separate the forward and reverse signal processing channels properly.<\/li>\r\n \t
    55. m<\/span>orphology<\/span><\/strong>\u2014The scientific study of the structure and form of animals and plants.<\/li>\r\n \t
    56. Morrison\u2019s pouch<\/span><\/strong>\u2014Area between the liver and right kidney.<\/li>\r\n \t
    57. m<\/span>otion <\/span>m<\/span>ode<\/span><\/strong>\u2014A one-dimensional position-versus-time ultrasound view of all changing or moving reflectors. This is used in echocardiography.<\/li>\r\n \t
    58. o<\/span>bstetrics<\/span><\/strong>\u2014The branch of medicine that deals with caring for and treating individuals during pregnancy, childbirth, and the postbirth period as well as the care of the newborn.<\/li>\r\n \t
    59. o<\/span>ligohydramnios<\/span><\/strong>\u2014A condition where there is reduced amniotic fluid around the baby during pregnancy.<\/li>\r\n \t
    60. o<\/span>phthalmology<\/span><\/strong>\u2014A branch of medicine involving anatomy, physiology, and conditions of the eye.<\/li>\r\n \t
    61. p<\/span>aracolic gutters<\/span><\/strong>\u2014Areas between the colon and the abdominal wall.<\/li>\r\n \t
    62. p<\/span>ediatrics<\/span><\/strong>\u2014A specialty providing medical care to <\/ins>infants, children, and adolescents.<\/li>\r\n \t
    63. p<\/span>erinatologist<\/span><\/strong>\u2014An obstetrician-gynecologist who specializes in high-risk pregnancies.<\/li>\r\n \t
    64. period<\/strong>\u2014Time per cycle.<\/li>\r\n \t
    65. p<\/span>hysiatry<\/span><\/strong>\u2014A branch of medicine that deals with the treatment of injuries or illnesses of the nerves, muscles, and bones. Also known as physical medicine and rehabilitation.<\/li>\r\n \t
    66. p<\/span>iezoelectric effect<\/span><\/strong>\u2014The ability of certain crystals to generate an electric charge in response to applied mechanical stress. Piezoelectric materials produce electrical signals when deformed or vice versa (i.e., the crystal changes shape and vibrates when a voltage is applied to it). These crystals are the primary components of ultrasound transducers.<\/li>\r\n \t
    67. p<\/span>ixel<\/span><\/strong>\u2014Picture elements; the unit into which imaging information is divided for storage and display.<\/li>\r\n \t
    68. p<\/span>olyhydramnios<\/span><\/strong>\u2014A condition when there is too much amniotic fluid around the baby during pregnancy.<\/li>\r\n \t
    69. p<\/span>osterior<\/span><\/strong>\u2014Relating to the back (for example, the shoulder blades are located on the posterior side of the body).<\/li>\r\n \t
    70. potential or power of hydrogen<\/strong>\u2014A measure of hydrogen ion concentration representing the acidity or basicity of aqueous or other liquid solutions.<\/li>\r\n \t
    71. p<\/span>ouch of Douglas<\/span><\/strong>\u2014The caudal extension of the peritoneal cavity. It is the rectovaginal pouch in the female and the rectovesical pouch in the male.<\/li>\r\n \t
    72. p<\/span>ropagation speed<\/span><\/strong>\u2014The speed at which a wave travels through a medium and is equal to the product of the wavelength and frequency. The average propagation speed of sound waves in a soft tissue is 1540 meters\/second.<\/li>\r\n \t
    73. p<\/span>roximal<\/span><\/strong>\u2014Toward or nearest the trunk or the point of origin of a part (for example, the proximal end of the femur joins with the pelvic bone).<\/li>\r\n \t
    74. p<\/span>ulsatility <\/span>i<\/span>ndex<\/span><\/strong>\u2014A dimensionless parameter that is used to assess pulsatility and is defined as the difference between maximum and minimum blood flow velocity, normalized to the average velocity.<\/li>\r\n \t
    75. p<\/span>ulsed Doppler<\/span><\/strong>\u2014A Doppler mechanism that transmits a coherent burst of sound waves into the tissue and waits for returning echoes from a specific location, then processes these echoes for Doppler shift frequency content.<\/li>\r\n \t
    76. p<\/span>ulse <\/span>r<\/span>epetition <\/span>f<\/span>requency<\/span><\/strong>\u2014The number of pulses per second.<\/li>\r\n \t
    77. p<\/span>ulse <\/span>r<\/span>epetition <\/span>p<\/span>eriod<\/span><\/strong>\u2014Interval of time from the beginning of one pulse to the beginning of the next.<\/li>\r\n \t
    78. r<\/span>arefaction<\/span><\/strong>\u2014A region in a longitudinal wave (like sound waves) where the particles are farthest apart.<\/li>\r\n \t
    79. r<\/span>eal-time display<\/span><\/strong>\u2014Immediate display of an ultrasound scan of moving structures made possible by the use of higher frame rates.<\/li>\r\n \t
    80. r<\/span>eflection<\/span><\/strong>\u2014Portion of the sound returned from a medial boundary (i.e., refers to the bending of the ultrasound beam at the boundary surface between two mediums with different acoustic impedances).<\/li>\r\n \t
    81. r<\/span>efraction<\/span><\/strong>\u2014Change of sound direction on passing from one medium to another.<\/li>\r\n \t
    82. r<\/span>egurgitation<\/span><\/strong>\u2014The flow of a fluid through a vessel or valve in the body in a direction opposite to normal.<\/li>\r\n \t
    83. r<\/span>enal <\/span>a<\/span>rterial <\/span>r<\/span>esistive <\/span>i<\/span>ndex<\/span><\/strong>\u2014An index used to assess the risk for renal arterial disease. It is commonly used to indicate renal function, pathology, prognosis, and responsiveness to steroid therapy in chronic kidney disease patients.<\/li>\r\n \t
    84. r<\/span>esolution<\/span><\/strong>\u2014Within sonography, represents the ability of an ultrasound system to distinguish between two closely spaced reflectors as separate structures.<\/li>\r\n \t
    85. r<\/span>everberation<\/span><\/strong>\u2014Artifact resulting from false echoes produced due to repeated reflections between two interfaces with a high acoustic impedance mismatch.<\/li>\r\n \t
    86. s<\/span>agittal <\/span>p<\/span>lane or <\/span>v<\/span>iew<\/span><\/strong>\u2014An anatomical plane that divides the body into right and left sections.<\/li>\r\n \t
    87. s<\/span>cattering<\/span><\/strong>\u2014Spreading of ultrasound beam in different directions as it strikes a boundary or interface between two small structures.<\/li>\r\n \t
    88. s<\/span>hadowing<\/span><\/strong>\u2014Reduction in echo amplitude from reflectors behind a strongly reflecting or attenuating structure.<\/li>\r\n \t
    89. s<\/span>onography<\/span><\/strong>\u2014The process of visualizing body structures using ultrasound.<\/li>\r\n \t
    90. s<\/span>patial<\/span><\/strong>\u2014Relating to the position, area, and size of things.<\/li>\r\n \t
    91. spatial resolution<\/strong>\u2014The minimum distance between two adjacent features that can be detected by the imaging system.<\/li>\r\n \t
    92. s<\/span>patiotemporal<\/span><\/strong>\u2014Relating to both space and time.<\/li>\r\n \t
    93. s<\/span>pectral <\/span>a<\/span>nalysis<\/span><\/strong>\u2014Separation of frequencies in a Doppler signal for display as a Doppler spectrum in the form of a neat graph.<\/li>\r\n \t
    94. s<\/span>pecular <\/span>r<\/span>eflection<\/span><\/strong>\u2014An optical process involving reflections from a large, smooth boundary.<\/li>\r\n \t
    95. s<\/span>tenosis<\/span><\/strong>\u2014An abnormal narrowing of a blood vessel or other tubular organ or structure such as foramina and canals.<\/li>\r\n \t
    96. s<\/span>uperior<\/span><\/strong>\u2014Toward the head end of the body; upper (for example, the hand is part of the superior extremity).<\/li>\r\n \t
    97. s<\/span>upine<\/span><\/strong>\u2014A position in which a person lies on their back with their face and torso pointing up.<\/li>\r\n \t
    98. s<\/span>urgery<\/span><\/strong>\u2014An invasive use of instruments to test, remove, or adjust an individual\u2019s original anatomy for treatment of illness, injury, or disease or cosmetic purposes.<\/li>\r\n \t
    99. s<\/span>ystemic <\/span>h<\/span>emodynamics<\/span><\/strong>\u2014Study of the relationship between arterial blood pressure and blood flow. Systemic hemodynamic state is the mean value of blood pressure and the mean value of blood flow over one heartbeat interval.<\/li>\r\n \t
    100. s<\/span>ystole<\/span><\/strong>\u2014Phase of the cardiac cycle in which the heart contracts and pumps out the blood.<\/li>\r\n \t
    101. t<\/span>emporal<\/span><\/strong>\u2014Relating to time.<\/li>\r\n \t
    102. t<\/span>hermal <\/span>i<\/span>ndex<\/span><\/strong>\u2014A value used as an indicator for the potential risk of tissue heating due to exposure to ultrasound.<\/li>\r\n \t
    103. thrombosis<\/strong>\u2014The development of blood clots inside blood vessels that obstruct blood flow in the circulatory system.<\/li>\r\n \t
    104. t<\/span>hrombus<\/span><\/strong>\u2014A blood clot in the circulatory system.<\/li>\r\n \t
    105. t<\/span>ransducer<\/span><\/strong>\u2014A device that converts variations in acoustic pressure to an electrical signal or vice versa.<\/li>\r\n \t
    106. t<\/span>ransmitter<\/span><\/strong>\u2014A device that uses an electrical current to generate acoustic vibrations or pulses.<\/li>\r\n \t
    107. t<\/span>ransverse <\/span>p<\/span>lane or <\/span>v<\/span>iew<\/span><\/strong>\u2014An anatomical plane that divides the body into superior and inferior sections.<\/li>\r\n \t
    108. t<\/span>rimester<\/span><\/strong>\u2014A period of three months during gestation. The human gestation period has three trimesters (first, second, and third).<\/li>\r\n \t
    109. t<\/span>urbulent <\/span>f<\/span>low<\/span><\/strong>\u2014A nonlaminar flow condition in which the kinetic energy of flow creates vortices. The overall fluid motion is complex and chaotic.<\/li>\r\n \t
    110. u<\/span>rology<\/span><\/strong>\u2014The study or medical treatment of diseases and conditions of the urinary tract system and certain reproductive organs.<\/li>\r\n \t
    111. v<\/span>alves<\/span><\/strong>\u2014A flap or leaflet, usually inside a tubular structure, that acts as a one-way inlet and permits fluids or gases to flow in just one direction.<\/li>\r\n \t
    112. v<\/span>entilator<\/span><\/strong>\u2014A device that supports or re-creates the process of breathing by pumping air into the lungs when a person is not able to breathe enough on their own.<\/li>\r\n \t
    113. v<\/span>entral<\/span><\/strong>\u2014See <\/em>a<\/em>nterior<\/em><\/span>.<\/li>\r\n \t
    114. v<\/span>iscosity<\/span><\/strong>\u2014A measure of the resistance of a fluid to flow. It is an indicator of the internal friction of a moving fluid. For example, a fluid with high viscosity flows slower than one with low viscosity.<\/li>\r\n<\/ol>","rendered":"
        \n
      1. a<\/span>bsorption<\/span><\/strong>\u2014The attenuation process involving ultrasound energy lost to tissue in the form of heat.<\/li>\n
      2. a<\/span>coustic<\/span><\/strong>\u2014Having to do with sound.<\/li>\n
      3. a<\/span>mniotic <\/span>f<\/span>luid<\/span><\/strong>\u2014A liquid that surrounds the fetus in the uterus.<\/li>\n
      4. a<\/span>mplifier<\/span><\/strong>\u2014An electronic device that enhances a signal, making the output signal stronger than the input signal.<\/li>\n
      5. a<\/span>mplitude<\/span><\/strong> (of a wave)\u2014Maximum displacement of a point on a wave or vibrating object relative to equilibrium position.<\/li>\n
      6. a<\/span>mplitude <\/span>m<\/span>ode<\/span><\/strong>\u2014A one-dimensional display mode used in diagnostic sonography in which the echo depth is on the horizontal axis and the amplitude is on the vertical axis.<\/li>\n
      7. a<\/span>nechoic<\/span><\/strong>\u2014Areas that appear dark on ultrasound because they do not reflect sound waves back to the transducer.<\/li>\n
      8. a<\/span>nesthesiology<\/span><\/strong>\u2014A branch of medical science dealing with anesthesia and anesthetics.<\/li>\n
      9. a<\/span>neurysm<\/span><\/strong>\u2014An unexpected balloon-like bulge in an artery. If it bursts or leaks, it can cause dangerous bleeding or even death. According to the National Institutes<\/ins> of Health, about 13,000 people die yearly in the United States from abdominal aortic aneurysms.<\/li>\n
      10. a<\/span>ngle of <\/span>i<\/span>nsonation<\/span><\/strong>\u2014Within sonography, the angle that the ultrasound beam makes relative to the tissue or organ of interest.<\/li>\n
      11. a<\/span>nisotropy<\/span><\/strong>\u2014An artifact on ultrasound images caused by variations in the angles of insonation produced by varying properties of tissue.<\/li>\n
      12. a<\/span>nterior<\/span><\/strong>\u2014Relating to the front (for example, the kneecap is located on the anterior side of the leg).<\/li>\n
      13. artifact<\/strong>\u2014A false portrayal of image anatomy usually characterized by an inappropriate brightness, shape, size, or position<\/li>\n
      14. \u201cAs Low As Reasonably Achievable<\/strong>\u201d<\/span>\u2014Refers to responsibly exposing the patient to the minimum energy possible to obtain appropriate diagnostic information.<\/li>\n
      15. a<\/span>therosclerosis<\/span><\/strong>\u2014A disease in which plaque (buildup of fat, cholesterol, calcium, or other products) builds up, subsequently narrowing the arteries and thus limiting the flow of oxygenated blood to organs and other parts of the body. This condition can lead to heart attack, stroke, or even death.<\/li>\n
      16. a<\/span>ttenuation<\/span><\/strong>\u2014The decrease in the energy and amplitude of a wave as it passes through a medium due to the effects of absorption, reflection, and scattering. As the beam passes through tissue, its intensity decreases over time.<\/li>\n
      17. a<\/span>xial <\/span>r<\/span>esolution<\/span><\/strong>\u2014The minimum distance between two reflectors along the sound path that can be resolved to produce separate sound waves.<\/li>\n
      18. Baker\u2019s <\/span>c<\/span>yst<\/span><\/strong>\u2014A fluid-filled growth behind the knee.<\/li>\n
      19. b<\/span>ioeffects of <\/span>u<\/span>ltrasound<\/span><\/strong>\u2014Within sonography, refers to the adverse effects of ultrasound beams on tissues (including soft tissue, body fluids, and bone).<\/li>\n
      20. b<\/span>iohazard<\/span><\/strong>\u2014Biological organisms or substances that can threaten human health.<\/li>\n
      21. b<\/span>iopsy<\/span><\/strong>\u2014A procedure medical professionals use to remove a piece of tissue or a sample of cells from the body for laboratory analysis.<\/li>\n
      22. b<\/span>lood <\/span>p<\/span>ressure<\/span><\/strong>\u2014Pressure created by blood against the walls of the arteries as the heart pumps it through the body.<\/li>\n
      23. b<\/span>rightness <\/span>m<\/span>ode<\/span><\/strong>\u2014A two-dimensional display mode used in diagnostic sonography in which the image is composed of bright dots representing the ultrasound echoes. The brightness of each dot is determined by the amplitude of the returned echo signal.<\/li>\n
      24. c<\/span>alcification<\/span><\/strong>\u2014A process of calcium buildup in body tissue that causes the tissue to harden.<\/li>\n
      25. c<\/span>ardiac <\/span>a<\/span>rrest<\/span><\/strong>\u2014An abrupt inability of the heart to contract and generate a pulse and adequate blood flow leading to starvation of blood in the brain and other organs.<\/li>\n
      26. c<\/span>ardiology<\/span><\/strong>\u2014A medical specialty that involves finding, treating, and preventing diseases of the heart and blood vessels.<\/li>\n
      27. c<\/span>ardiopulmonary <\/span>r<\/span>esuscitation<\/span><\/strong>\u2014A lifesaving procedure performed by combining rescue breathing (mouth-to-mouth) and chest compressions to temporarily pump enough blood to the brain when the heart stops beating and until specialized treatment is available.<\/li>\n
      28. c<\/span>audal<\/span><\/strong>\u2014See <\/em>i<\/em>nferior<\/em><\/span>.<\/li>\n
      29. c<\/span>avitation<\/span><\/strong>\u2014Production and dynamics of bubbles caused by sound waves. The bubbles oscillate inside the tissue due to the rapidly changing acoustic pressure.<\/li>\n
      30. c<\/span>ircle of Willis<\/span><\/strong>\u2014A complete ring of arteries at the base of the brain that is formed by the cerebral and communicating arteries.<\/li>\n
      31. c<\/span>olor Doppler <\/span>d<\/span>isplay<\/span><\/strong>\u2014Two-dimensional, real-time Doppler shift information superimposed on a real-time, grayscale, anatomic cross-sectional image. Flow directions display different colors.<\/li>\n
      32. c<\/span>omet <\/span>t<\/span>ail<\/span><\/strong>\u2014A series of closely spaced reverberation echoes.<\/li>\n
      33. c<\/span>ompression<\/span><\/strong>\u2014A region in a longitudinal wave (like sound waves) where the particles are closest together.<\/li>\n
      34. c<\/span>omputerized <\/span>t<\/span>omography<\/span><\/strong>\u2014An imaging technique that combines a series of X-ray images taken from different angles around the body.<\/li>\n
      35. c<\/span>ontinuous <\/span>w<\/span>ave Doppler<\/span><\/strong>\u2014An imaging mode in which the transducer uses two crystals: one for continuous transmission and the other for reception of ultrasound signals. This technique allows measurements of high-velocity flows, especially in the heart.<\/li>\n
      36. c<\/span>ontrast <\/span>r<\/span>esolution<\/span><\/strong>\u2014The ability to distinguish echoes of slightly different intensities on a grayscale display.<\/li>\n
      37. Coronavirus <\/span>d<\/span>isease 2019<\/span><\/strong>\u2014An infectious disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus that was discovered in 2019.<\/li>\n
      38. c<\/span>oupling <\/span>m<\/span>edium<\/span><\/strong>\u2014Within sonography, a gel that is applied between the tissue surface, typically skin, and the ultrasound transducer to displace air at the boundary surface and transmit sound waves through the skin.<\/li>\n
      39. c<\/span>ranial<\/span><\/strong>\u2014See <\/em>s<\/em>uperior<\/em><\/span>.<\/li>\n
      40. c<\/span>ritical <\/span>c<\/span>are<\/span><\/strong>\u2014A branch of medicine focused on the care of people with life-threatening or critical injuries and illnesses requiring more specialized care.<\/li>\n
      41. c<\/span>ross<\/span> section<\/span><\/strong>\u2014A transverse cut through a structure or tissue.<\/li>\n
      42. c<\/span>ycle<\/span><\/strong>\u2014Within sonography, represents the combination of one rarefaction and one compression of a sound wave.<\/li>\n
      43. c<\/span>yst<\/span><\/strong>\u2014An abnormal sac or cavity in the body containing fluid or semisolid material.<\/li>\n
      44. d<\/span>eep<\/span><\/strong>\u2014Position that is closer to the interior center of the body.<\/li>\n
      45. d<\/span>ermatology<\/span><\/strong>\u2014A branch of medicine dealing with the skin, its structure, and its diseases.<\/li>\n
      46. d<\/span>iastole<\/span><\/strong>\u2014A phase in the cardiac cycle during which the heart relaxes and allows blood to refill.<\/li>\n
      47. d<\/span>iffraction<\/span><\/strong>\u2014Refers to the bending of an ultrasound beam when it passes around an edge or through a narrow opening.<\/li>\n
      48. d<\/span>istal<\/span><\/strong>\u2014Away from or farthest from the trunk or the point or origin of a part (for example, the hand is located at the distal end of the forearm).<\/li>\n
      49. Doppler <\/span>a<\/span>ngle<\/span><\/strong>\u2014The angle between the sound beam and the flow direction.<\/li>\n
      50. Doppler <\/span>e<\/span>ffect<\/span><\/strong>\u2014A shift in frequency received by the transducer secondary to the sound wave reflecting off a moving object, such as a moving collection of red blood cells. Within sonography, this phenomenon is used to measure the flow velocity of the blood during echocardiography.<\/li>\n
      51. Doppler <\/span>e<\/span>quation<\/span><\/strong>\u2014Relates the various parameters that affect the Doppler shift frequency. The equation is<\/li>\n<\/ol>\n
        \"Equation<\/div>\n

        where f<\/em>s<\/em><\/sub><\/span> is the Doppler shift frequency, v<\/em><\/span> is the receiver (target) velocity, \u03b8<\/em><\/span> is the Doppler angle, and c<\/em><\/span> is the speed of sound in tissue, which is 1540 m\/s.<\/p>\n

          \n
        1. Doppler <\/span>s<\/span>hift <\/span>f<\/span>requency<\/span><\/strong>\u2014The amount of change in frequency caused by the Doppler effect.<\/li>\n
        2. d<\/span>orsal<\/span><\/strong>\u2014See <\/em>p<\/em>osterior<\/em><\/span>.<\/li>\n
        3. d<\/span>uplex <\/span>i<\/span>maging<\/span><\/strong>\u2014A process of combining two-dimensional real-time imaging with Doppler signal processing.<\/li>\n
        4. e<\/span>cho<\/span><\/strong>\u2014Within sonography, a reflected ultrasound signal. The signals are converted by the processor into gray dots on the ultrasound display.<\/li>\n
        5. e<\/span>chocardiography<\/span><\/strong>\u2014A diagnostic ultrasound test used to evaluate cardiac anatomy and physiology.<\/li>\n
        6. e<\/span>ddies<\/span><\/strong>\u2014Regions of circular flow patterns present within turbulent flow patterns.<\/li>\n
        7. e<\/span>dema<\/span><\/strong>\u2014Swelling caused by too much fluid trapped in the body\u2019s tissues.<\/li>\n
        8. e<\/span>ffusion<\/span><\/strong>\u2014An excessive accumulation of fluid in a region or a structure.<\/li>\n
        9. e<\/span>mergency <\/span>m<\/span>edicine<\/span><\/strong>\u2014A medical specialty involving care for patients with acute illnesses or injuries requiring immediate medical attention.<\/li>\n
        10. e<\/span>mphysema<\/span><\/strong>\u2014A lung condition that causes shortness of breath due to damaged air sacs in the lungs.<\/li>\n
        11. f<\/span>ascia<\/span><\/strong>\u2014A thin casing of connective tissue that surrounds and holds every organ, blood vessel, bone, nerve fiber, and muscle in place.<\/li>\n
        12. f<\/span>ibrosis<\/span><\/strong>\u2014Scarring and hardening of tissues and organs.<\/li>\n
        13. f<\/span>lexion<\/span><\/strong>\u2014Bending of an arm or leg. It\u2019s a physical position that decreases the angle between the bones of the limb at a joint.<\/li>\n
        14. f<\/span>ocal <\/span>l<\/span>ength<\/span><\/strong>\u2014The distance from the scanning face of a transducer to the focus.<\/li>\n
        15. f<\/span>ocus<\/span><\/strong>\u2014A narrow point in the cross section of the ultrasound beam. To improve the resolution at a given depth, the transducer must be focused in order to narrow the beam width. This is performed by varying the number of transmitting and receiving elements and delaying the signal once received.<\/li>\n
        16. f<\/span>rame<\/span><\/strong>\u2014A single image produced by one complete scan of the sound beam.<\/li>\n
        17. f<\/span>rame <\/span>r<\/span>ate<\/span><\/strong>\u2014The number of frames of echo information stored each second.<\/li>\n
        18. f<\/span>requency<\/span><\/strong>\u2014The number of cycles per second. In diagnostic ultrasound, it is usually demonstrated in megahertz.<\/li>\n
        19. f<\/span>riction<\/span><\/strong>\u2014Within sonography, the force that resists the relative motion between blood and the cardiovascular walls.<\/li>\n
        20. g<\/span>ain<\/span><\/strong>\u2014The degree of amplification of the returning echo.<\/li>\n
        21. g<\/span>ate<\/span><\/strong>\u2014A device that allows only echoes from selected depths to pass.<\/li>\n
        22. g<\/span>estation<\/span><\/strong>\u2014The process or period of development inside the womb between conception and birth.<\/li>\n
        23. g<\/span>rating<\/span><\/strong>\u2014The process in which an input ultrasound beam splits into multiple beams after passing tissue, resulting in the formation of side lobe artifacts.<\/li>\n
        24. g<\/span>rayscale<\/span><\/strong>\u2014The range of brightness between white and black. The dark color indicates the total absence of reflected light, and the bright represents reflected light.<\/li>\n
        25. g<\/span>ynecology<\/span><\/strong>\u2014A specialty of the female reproductive system, including the diagnosis and treatment of conditions, disorders, and diseases.<\/li>\n
        26. h<\/span>armonics<\/span><\/strong>\u2014Frequencies that are even and odd multiples of one another.<\/li>\n
        27. h<\/span>ertz<\/span><\/strong>\u2014Unit of frequency, one cycle per second.<\/li>\n
        28. h<\/span>ydrocephalus<\/span><\/strong>\u2014A neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles or cavities deep within the brain.<\/li>\n
        29. h<\/span>ydronephrosis<\/span><\/strong>\u2014Swelling of a kidney due to urine failing to drain properly from the kidney to the bladder.<\/li>\n
        30. h<\/span>yperechoic<\/span><\/strong>\u2014Areas on the image with more reflected echoes that appear brighter than the surrounding tissue.<\/li>\n
        31. h<\/span>ypertension<\/span><\/strong>\u2014High systolic and\/or diastolic blood pressure.<\/li>\n
        32. h<\/span>ypoechoic<\/span><\/strong>\u2014Areas on the image with fewer reflected echoes that appear darker than the surrounding tissue.<\/li>\n
        33. h<\/span>ysterectomy<\/span><\/strong>\u2014A surgical removal of the uterus.<\/li>\n
        34. i<\/span>mpedance<\/span><\/strong>\u2014The resistance to the propagation of ultrasound waves through tissues. It is determined by the density of the tissue and the sound propagation speed.<\/li>\n
        35. i<\/span>nertia<\/span><\/strong>\u2014Resistance to change in the state of either rest or motion or the tendency to keep moving in a straight line at a constant velocity.<\/li>\n
        36. i<\/span>nferior<\/span><\/strong>\u2014Away from the head; lower (for example, the foot is part of the inferior extremity).<\/li>\n
        37. i<\/span>ntensity<\/span><\/strong>\u2014The power per unit area,<\/ins> usually expressed in milliwatts per square centimeter in sonographic discussions. It is the ultrasound power transferred per unit area.<\/li>\n
        38. i<\/span>nternal <\/span>m<\/span>edicine<\/span><\/strong>\u2014A branch of medicine that deals with long-term care involving common and complex illnesses such as the diagnosis and treatment of cancer, infections, and diseases affecting the heart, blood, kidneys, joints, and digestive, respiratory, and vascular systems in adolescents, adults, and elderly individuals.<\/li>\n
        39. i<\/span>ntima-<\/span>m<\/span>edia <\/span>t<\/span>hickness <\/span>a<\/span>nalysis<\/span><\/strong>\u2014An ultrasound measurement of the thickness of the two inner layers of the carotid arteries\u2014the intima and media. Abnormal thickening of the arterial walls of the carotid arteries indicates a high risk for heart attack or stroke.<\/li>\n
        40. i<\/span>ntrarenal <\/span>p<\/span>erfusion<\/span><\/strong>\u2014Fluid injection into the renal blood vessels to or from the kidneys.<\/li>\n
        41. l<\/span>aminar <\/span>f<\/span>low<\/span><\/strong>\u2014Demonstration of fluid moving in an organized direction as if it were made up of layers that glide over one another.<\/li>\n
        42. l<\/span>ateral<\/span><\/strong>\u2014Away from the midline of the body (for example, the little toe is located at the lateral side of the foot).<\/li>\n
        43. l<\/span>ateral <\/span>r<\/span>esolution<\/span><\/strong>\u2014Refers to reflectors that lie perpendicular to the axis of the ultrasound beam. The resolution is related to the beam width; that is, the wider the beam, the poorer the lateral resolution. An ultrasound beam is the narrowest at its focal length, and this is where the lateral resolution will be the best.<\/li>\n
        44. l<\/span>ateral <\/span>r<\/span>otation<\/span><\/strong>\u2014Lateral rotation of the upper limb at the shoulder or lower limb at the hip involves turning the anterior surface of the limb away from the midline of the body. Lateral rotation is also referred to as exterior rotation.<\/li>\n
        45. l<\/span>inear <\/span>a<\/span>rray<\/span><\/strong>\u2014An array made of rectangular elements arranged in a line.<\/li>\n
        46. l<\/span>inear <\/span>p<\/span>hased <\/span>a<\/span>rray<\/span><\/strong>\u2014A linear array that operates by applying voltage pulses to all elements with small time differences to direct sound waves out in various directions.<\/li>\n
        47. l<\/span>inear <\/span>s<\/span>equenced <\/span>a<\/span>rray<\/span><\/strong>\u2014A linear array that operates by applying voltage pulses to groups of elements in a sequence.<\/li>\n
        48. Lister\u2019s tubercle<\/span><\/strong>\u2014A bony prominence located at the distal end of the radius.<\/li>\n
        49. l<\/span>umen<\/span><\/strong>\u2014An inner open space or cavity of a tubular structure, as of a blood vessel or an intestine.<\/li>\n
        50. m<\/span>aternity<\/span><\/strong>\u2014The period during and immediately after pregnancy.<\/li>\n
        51. m<\/span>echanical index<\/span><\/strong>\u2014A value used to estimate the cavitation effect during exposure to ultrasound energy.<\/li>\n
        52. m<\/span>edial<\/span><\/strong>\u2014Relating to the midline of the body (for example, the middle toe is located at the medial side of the foot).<\/li>\n
        53. m<\/span>edial <\/span>r<\/span>otation<\/span><\/strong>\u2014Medial rotation of the upper limb at the shoulder or lower limb at the hip involves turning the anterior surface of the limb toward the midline of the body. Medial rotation is also referred to as internal rotation.<\/li>\n
        54. m<\/span>irroring<\/span><\/strong>\u2014An artifact on a spectral display caused by an inability to separate the forward and reverse signal processing channels properly.<\/li>\n
        55. m<\/span>orphology<\/span><\/strong>\u2014The scientific study of the structure and form of animals and plants.<\/li>\n
        56. Morrison\u2019s pouch<\/span><\/strong>\u2014Area between the liver and right kidney.<\/li>\n
        57. m<\/span>otion <\/span>m<\/span>ode<\/span><\/strong>\u2014A one-dimensional position-versus-time ultrasound view of all changing or moving reflectors. This is used in echocardiography.<\/li>\n
        58. o<\/span>bstetrics<\/span><\/strong>\u2014The branch of medicine that deals with caring for and treating individuals during pregnancy, childbirth, and the postbirth period as well as the care of the newborn.<\/li>\n
        59. o<\/span>ligohydramnios<\/span><\/strong>\u2014A condition where there is reduced amniotic fluid around the baby during pregnancy.<\/li>\n
        60. o<\/span>phthalmology<\/span><\/strong>\u2014A branch of medicine involving anatomy, physiology, and conditions of the eye.<\/li>\n
        61. p<\/span>aracolic gutters<\/span><\/strong>\u2014Areas between the colon and the abdominal wall.<\/li>\n
        62. p<\/span>ediatrics<\/span><\/strong>\u2014A specialty providing medical care to <\/ins>infants, children, and adolescents.<\/li>\n
        63. p<\/span>erinatologist<\/span><\/strong>\u2014An obstetrician-gynecologist who specializes in high-risk pregnancies.<\/li>\n
        64. period<\/strong>\u2014Time per cycle.<\/li>\n
        65. p<\/span>hysiatry<\/span><\/strong>\u2014A branch of medicine that deals with the treatment of injuries or illnesses of the nerves, muscles, and bones. Also known as physical medicine and rehabilitation.<\/li>\n
        66. p<\/span>iezoelectric effect<\/span><\/strong>\u2014The ability of certain crystals to generate an electric charge in response to applied mechanical stress. Piezoelectric materials produce electrical signals when deformed or vice versa (i.e., the crystal changes shape and vibrates when a voltage is applied to it). These crystals are the primary components of ultrasound transducers.<\/li>\n
        67. p<\/span>ixel<\/span><\/strong>\u2014Picture elements; the unit into which imaging information is divided for storage and display.<\/li>\n
        68. p<\/span>olyhydramnios<\/span><\/strong>\u2014A condition when there is too much amniotic fluid around the baby during pregnancy.<\/li>\n
        69. p<\/span>osterior<\/span><\/strong>\u2014Relating to the back (for example, the shoulder blades are located on the posterior side of the body).<\/li>\n
        70. potential or power of hydrogen<\/strong>\u2014A measure of hydrogen ion concentration representing the acidity or basicity of aqueous or other liquid solutions.<\/li>\n
        71. p<\/span>ouch of Douglas<\/span><\/strong>\u2014The caudal extension of the peritoneal cavity. It is the rectovaginal pouch in the female and the rectovesical pouch in the male.<\/li>\n
        72. p<\/span>ropagation speed<\/span><\/strong>\u2014The speed at which a wave travels through a medium and is equal to the product of the wavelength and frequency. The average propagation speed of sound waves in a soft tissue is 1540 meters\/second.<\/li>\n
        73. p<\/span>roximal<\/span><\/strong>\u2014Toward or nearest the trunk or the point of origin of a part (for example, the proximal end of the femur joins with the pelvic bone).<\/li>\n
        74. p<\/span>ulsatility <\/span>i<\/span>ndex<\/span><\/strong>\u2014A dimensionless parameter that is used to assess pulsatility and is defined as the difference between maximum and minimum blood flow velocity, normalized to the average velocity.<\/li>\n
        75. p<\/span>ulsed Doppler<\/span><\/strong>\u2014A Doppler mechanism that transmits a coherent burst of sound waves into the tissue and waits for returning echoes from a specific location, then processes these echoes for Doppler shift frequency content.<\/li>\n
        76. p<\/span>ulse <\/span>r<\/span>epetition <\/span>f<\/span>requency<\/span><\/strong>\u2014The number of pulses per second.<\/li>\n
        77. p<\/span>ulse <\/span>r<\/span>epetition <\/span>p<\/span>eriod<\/span><\/strong>\u2014Interval of time from the beginning of one pulse to the beginning of the next.<\/li>\n
        78. r<\/span>arefaction<\/span><\/strong>\u2014A region in a longitudinal wave (like sound waves) where the particles are farthest apart.<\/li>\n
        79. r<\/span>eal-time display<\/span><\/strong>\u2014Immediate display of an ultrasound scan of moving structures made possible by the use of higher frame rates.<\/li>\n
        80. r<\/span>eflection<\/span><\/strong>\u2014Portion of the sound returned from a medial boundary (i.e., refers to the bending of the ultrasound beam at the boundary surface between two mediums with different acoustic impedances).<\/li>\n
        81. r<\/span>efraction<\/span><\/strong>\u2014Change of sound direction on passing from one medium to another.<\/li>\n
        82. r<\/span>egurgitation<\/span><\/strong>\u2014The flow of a fluid through a vessel or valve in the body in a direction opposite to normal.<\/li>\n
        83. r<\/span>enal <\/span>a<\/span>rterial <\/span>r<\/span>esistive <\/span>i<\/span>ndex<\/span><\/strong>\u2014An index used to assess the risk for renal arterial disease. It is commonly used to indicate renal function, pathology, prognosis, and responsiveness to steroid therapy in chronic kidney disease patients.<\/li>\n
        84. r<\/span>esolution<\/span><\/strong>\u2014Within sonography, represents the ability of an ultrasound system to distinguish between two closely spaced reflectors as separate structures.<\/li>\n
        85. r<\/span>everberation<\/span><\/strong>\u2014Artifact resulting from false echoes produced due to repeated reflections between two interfaces with a high acoustic impedance mismatch.<\/li>\n
        86. s<\/span>agittal <\/span>p<\/span>lane or <\/span>v<\/span>iew<\/span><\/strong>\u2014An anatomical plane that divides the body into right and left sections.<\/li>\n
        87. s<\/span>cattering<\/span><\/strong>\u2014Spreading of ultrasound beam in different directions as it strikes a boundary or interface between two small structures.<\/li>\n
        88. s<\/span>hadowing<\/span><\/strong>\u2014Reduction in echo amplitude from reflectors behind a strongly reflecting or attenuating structure.<\/li>\n
        89. s<\/span>onography<\/span><\/strong>\u2014The process of visualizing body structures using ultrasound.<\/li>\n
        90. s<\/span>patial<\/span><\/strong>\u2014Relating to the position, area, and size of things.<\/li>\n
        91. spatial resolution<\/strong>\u2014The minimum distance between two adjacent features that can be detected by the imaging system.<\/li>\n
        92. s<\/span>patiotemporal<\/span><\/strong>\u2014Relating to both space and time.<\/li>\n
        93. s<\/span>pectral <\/span>a<\/span>nalysis<\/span><\/strong>\u2014Separation of frequencies in a Doppler signal for display as a Doppler spectrum in the form of a neat graph.<\/li>\n
        94. s<\/span>pecular <\/span>r<\/span>eflection<\/span><\/strong>\u2014An optical process involving reflections from a large, smooth boundary.<\/li>\n
        95. s<\/span>tenosis<\/span><\/strong>\u2014An abnormal narrowing of a blood vessel or other tubular organ or structure such as foramina and canals.<\/li>\n
        96. s<\/span>uperior<\/span><\/strong>\u2014Toward the head end of the body; upper (for example, the hand is part of the superior extremity).<\/li>\n
        97. s<\/span>upine<\/span><\/strong>\u2014A position in which a person lies on their back with their face and torso pointing up.<\/li>\n
        98. s<\/span>urgery<\/span><\/strong>\u2014An invasive use of instruments to test, remove, or adjust an individual\u2019s original anatomy for treatment of illness, injury, or disease or cosmetic purposes.<\/li>\n
        99. s<\/span>ystemic <\/span>h<\/span>emodynamics<\/span><\/strong>\u2014Study of the relationship between arterial blood pressure and blood flow. Systemic hemodynamic state is the mean value of blood pressure and the mean value of blood flow over one heartbeat interval.<\/li>\n
        100. s<\/span>ystole<\/span><\/strong>\u2014Phase of the cardiac cycle in which the heart contracts and pumps out the blood.<\/li>\n
        101. t<\/span>emporal<\/span><\/strong>\u2014Relating to time.<\/li>\n
        102. t<\/span>hermal <\/span>i<\/span>ndex<\/span><\/strong>\u2014A value used as an indicator for the potential risk of tissue heating due to exposure to ultrasound.<\/li>\n
        103. thrombosis<\/strong>\u2014The development of blood clots inside blood vessels that obstruct blood flow in the circulatory system.<\/li>\n
        104. t<\/span>hrombus<\/span><\/strong>\u2014A blood clot in the circulatory system.<\/li>\n
        105. t<\/span>ransducer<\/span><\/strong>\u2014A device that converts variations in acoustic pressure to an electrical signal or vice versa.<\/li>\n
        106. t<\/span>ransmitter<\/span><\/strong>\u2014A device that uses an electrical current to generate acoustic vibrations or pulses.<\/li>\n
        107. t<\/span>ransverse <\/span>p<\/span>lane or <\/span>v<\/span>iew<\/span><\/strong>\u2014An anatomical plane that divides the body into superior and inferior sections.<\/li>\n
        108. t<\/span>rimester<\/span><\/strong>\u2014A period of three months during gestation. The human gestation period has three trimesters (first, second, and third).<\/li>\n
        109. t<\/span>urbulent <\/span>f<\/span>low<\/span><\/strong>\u2014A nonlaminar flow condition in which the kinetic energy of flow creates vortices. The overall fluid motion is complex and chaotic.<\/li>\n
        110. u<\/span>rology<\/span><\/strong>\u2014The study or medical treatment of diseases and conditions of the urinary tract system and certain reproductive organs.<\/li>\n
        111. v<\/span>alves<\/span><\/strong>\u2014A flap or leaflet, usually inside a tubular structure, that acts as a one-way inlet and permits fluids or gases to flow in just one direction.<\/li>\n
        112. v<\/span>entilator<\/span><\/strong>\u2014A device that supports or re-creates the process of breathing by pumping air into the lungs when a person is not able to breathe enough on their own.<\/li>\n
        113. v<\/span>entral<\/span><\/strong>\u2014See <\/em>a<\/em>nterior<\/em><\/span>.<\/li>\n
        114. v<\/span>iscosity<\/span><\/strong>\u2014A measure of the resistance of a fluid to flow. It is an indicator of the internal friction of a moving fluid. For example, a fluid with high viscosity flows slower than one with low viscosity.<\/li>\n<\/ol>\n","protected":false},"author":13,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"front-matter-type":[],"contributor":[],"license":[],"_links":{"self":[{"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter\/272"}],"collection":[{"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter"}],"about":[{"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/wp\/v2\/types\/front-matter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/wp\/v2\/users\/13"}],"version-history":[{"count":7,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter\/272\/revisions"}],"predecessor-version":[{"id":643,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter\/272\/revisions\/643"}],"metadata":[{"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter\/272\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/wp\/v2\/media?parent=272"}],"wp:term":[{"taxonomy":"front-matter-type","embeddable":true,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/pressbooks\/v2\/front-matter-type?post=272"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/wp\/v2\/contributor?post=272"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.palni.org\/ultrasoundphysicsanditsapplicationinmedicine\/wp-json\/wp\/v2\/license?post=272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}