In vitro ultrasound characterization of coronary arteries at 50 MHz

Ultrasonic attenuation coefficient, wave speed and integrated backscattering coefficient (IBC) of human coronary arteries were evaluated, in vitro, over the -6 dB frequency bandwidth of 35-68 MHz, for a total of 44 artery samples (normal and diseased). The wave speed measurements (average over the entire vessel wall thickness) varied from 1507 to 1746 m/s with a population mean (+/- one standard deviation) of 1575.92 (+/- 52.29) m/s. At 50 MHz the attenuation coefficient, 5.08 (+/- 1.31) dB/mm, varied between 3.0 and 8.6 dB/mm. Over the frequency range of 35-68 MHz, the frequency exponent of the attenuation coefficient, 1.53 (+/- 0.18), varied between 1.11 and 1.88. IBC results for the media layers are within 2.0x10(-3) and 8.0x10(-3) (Sr.mm)(-1), while those for intima and adventitia fall between 10(-2) and 10(-1) (Sr.mm)(-1). Plots of IBC as a function of depth show the potential for using IBC to differentiate between normal and diseased vessel walls.