Relationship between tissue characterization with 40 MHz intravascular ultrasound imaging and 64-slice computed tomography

BackgroundIdentification of coronary plaque composition is important for selecting the treatment strategy, and 64-slice computed tomography (CT) is a noninvasive method of characterizing atherosclerotic plaques. However, the correlation between plaque characteristics detected by CT and intravascular ultrasound (IVUS) is not clear. A 40 MHz IVUS imaging system (iMap-IVUS) has recently been developed to evaluate plaque composition. The aim of this study was to compare iMap-IVUS with 64-slice CT angiography for the characterization of non-calcified coronary plaques.Methods and resultsBoth 64-slice CT angiography and iMap-IVUS were performed in 19 patients (38 plaques). CT values were measured as Hounsfield units (HU) in circular regions of interest (ROI) drawn on the plaques. The iMap-IVUS system analyzed coronary plaques as fibrotic, lipidic, necrotic, or calcified tissue based on the radiofrequency spectrum.A positive correlation was found between CT values and the percentage of fibrotic plaque (r = 0.34, p = 0.036) or calcified plaque (r = 0.40, p = 0.011). Conversely, a negative correlation was found between CT values and the percentage of lipidic plaque (r = ?0.41, p = 0.01), or necrotic plaque (r = ?0.41, p = 0.01).ConclusionsGood correlations were observed between the characteristics of non-calcified plaque determined by iMap-IVUS and the CT values of plaque detected by 64-slice CT scanning.