Characterisation of atherosclerotic plaque by spectral analysis of intravascular ultrasound: An in vitro methodology

Raw 30-MHz intravascular ultrasound data have been captured from postmortem coronary arteries (n = 4) to develop radio frequency analysis techniques for the characterisation of atherosclerotic plaque, Digitised data acquired from positions (n = 8) within diseased sections of artery were compared with the corresponding histology and radiology, Scan-converted images were used to locate regions of interest (ROI = 33) within areas of known tissue composition: loose fibrotic tissue (LFT), dense fibrotic tissue (DFT) and calcium (CA), A range of parameters was extracted from the normalised power spectrum of each ROI within the bandwidth 17-42 MHz, Significant discrimination between LFT/DFT and between LFT/CA was provided by maximum power and spectral slope (dBMHz(-1)). However, the greatest discriminative power was given by the y-axis (0 Hz) intercept of the spectral slope: LFT/DFT (p = 0.001); LFT/CA (p = 0.0001); and DFT/CA (p = 0.089). (C) 1997 World Federation for Ultrasound in Medicine & Biology.