Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries

Objective-To test the efficacy of high frequency intravascular ultrasound ( IVUS) transducers in identifying lipid/necrotic pools in atherosclerotic pl aques. Methods-40 MHz transducers were used for in vitro IVUS assessment of 12 art erial segments (10 coronary and two carotid arteries, dissected from five d ifferent necropsy cases). IVUS acquisition was performed at 0.5 mm/s after ligature of the branching points to generate a closed system. Lipid/necroti c areas were defined by IVUS as large echolucent intraplaque areas surround ed by tissue with higher echodensity. To obtain histopathological sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm long segments using the most distal recorded IVUS image as the starri ng reference. Samples were then fixed with 10% buffered formalin, processed for histopathological study, serially cut, and stained using the Movat pen tacrome method. Results-122 sections were analysed. Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of th ese sections (16%; sensitivity 65%, specificity 95%). Conclusions-In vitro assessment of lipid/necrotic pools with high frequency transducers was achieved with good accuracy. This opens new perspectives f or future IVUS characterisation of atherosclerotic plaques.