Speed of ultrasound in body tissues is around:
A. 20,000 meters per second
B. 1500 meters per second
C. 340 meters per second
D. 10,000 meters per second
Correct answer: B. 1500 meters per second
Speed of ultrasound is almost that in water, though there is some difference between various tissues. Reflections of ultrasound occur at interfaces between tissues and between blood and tissues, due to the difference in velocity. Velocity of ultrasound and the time taken for the reflection is used to calculate the distance of the structure from the transducer. Ultrasound image is the result of multiple spots of echo received by the transducer merged into an image depending of the time delay into an image by the ultrasound machine. Image along a single line is M-Mode while there are higher modes of two and three dimensional imaging.
Reference: Braunwald’s Heart Disease, 12th Edition, Page 197