PARAMETRIC (INTEGRATED BACKSCATTER AND ATTENUATION) IMAGES CONSTRUCTED USING BACKSCATTERED RADIO-FREQUENCY SIGNALS (25-56 MHZ) FROM HUMAN AORTAE IN-VITRO

Quantitative ultrasonic tissue characterization using backscattered hi gh-frequency intravascular ultrasound could provide a basis for the ob jective identification of lesions in vivo, Representation of local mea surements of quantitative ultrasonic parameters in a conventional imag e format should facilitate their interpretation and thus increase thei r clinical utility, Toward this goal, the apparent integrated backscat ter, the slope of attenuation (25-56 MHz) and the value of the attenua tion on the linear fit at 37.5 MHz were measured using the backscatter ed radio frequency signals from in vitro human aortae, Local estimatio ns of these ultrasonic parameters from both normal and atherosclerotic aortic segments were displayed in a B-scan format, The morphological features of these parametric images corresponded well to features of h istological images of the same regions, The attenuation from 25-56 MHz of seven segments of the medial layer (both with and without overlyin g atheroma) were measured using the multinarrow-band backscatter metho d, The average attenuation in the media at 24 degrees C +/- 3 degrees C was 45 +/- 16 dB/cm at 25 MHz and 102 +/- 13 dB/cm at 50 MHz. This w ork represents progress toward the development of quantitative imaging methods for intravascular applications. (C) 1997 World Federation for Ultrasound in Medicine & Biology.