Velocity and attenuation of sound in arterial tissues

The velocity and attenuation of sound has been determined for freshly excised human and canine arterial tissues using a time delay spectrometer (TDS) technique. Frequency was swept from 0 to 10 MHz with data being taken in the range from 2 to 10 MHz. The velocity was determined using a comparison of the time delay for the received signal between a water path and a sample tissue of measured thickness. The velocity of sound was measured for various pathologies and related to biochemical assays of tissue. It was found to increase with increasing ultrasound attenuation of the tissue. The velocity was shown to increase with increased collagen, C, expressed as a percentage of wet weight of the tissue, [V = 17.8* C + 1561 m/s at 37 degrees C, r = 0.77] but was strongly dependent on tissue cholesterol or low levels of calcium. For highly calcified lesions, the velocity of sound was found to be approximately 2000 m/s at 37 degrees C.