Medical Ultrasound Imaging
Monday, 29 April 2024
 Info Sheets  Out- side     | 'Blood Flow-Velocity' Searchterm 'Blood Flow-Velocity' found in 1 article 1 definition [ • ] Result Pages : •
Sound waves must have a medium to pass through. The velocity or propagation speed is the speed at which sound waves travel through a particular medium measured in meters per second (m/s) or millimeters per microsecond (mm/μs). Because the velocity of ultrasound waves is constant, the time taken for the wave to return to the probe can be used to determine the depth of the object causing the reflection. The velocity is equal to the frequency x wavelength. V = f x l The velocity of ultrasound will differ with different media. In general, the propagation speed of sound through gases is low, liquids higher and solids highest. The speed of sound depends strongly on temperature as well as the medium through which sound waves are propagating. At 0 °C (32 °F) the speed of sound in air is about 331 m/s (1,086 ft/s; 1,192 km/h; 740 mph; 643 kn), at 20 °C (68 °F) about 343 metres per second (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn) Velocity (m/s)
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air: 331;
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fat: 1450;
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water (50 °C): 1540;
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human soft tissue: 1540;
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brain: 1541;
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liver: 1549;
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kidney: 1561;
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blood: 1570;
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muscle: 1585;
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lens of eye: 1620;
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bone: 4080.
Doppler ultrasound visualizes blood flow-velocity information. The peak systolic velocity and the end diastolic velocity are major Doppler parameters, which are determined from the spectrum obtained at the point of maximal vessel narrowing. Peak systolic velocity ratios are calculated by dividing the peak-systolic velocity measured at the site of flow disturbance by that measured proximal of the narrowing (stenosis, graft, etc.). See Acceleration Index, Acceleration Time, Modal Velocity, Run-time Artifact and Maximum Velocity.  Further Reading: Basics:
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[last update: 2023-11-06 01:42:00]