Comparison of 64-Slice Multidetector Computed Tomography With Spectral Analysis of Intravascular Ultrasound Backscatter Signals for Characterizations of Noncalcified Coronary Arterial Plaques

In vivo identification of plaque composition may allow the detection of vulnerable plaques before rupture. However, the clinical relevance of multidetector computed tomography (MDCT) in characterizing coronary plaques is currently a subject of debate. We compared 64-slice MDCT with virtual histology to investigate the potential role of 64-slice MDCT in the differentiation of composition of noncalcified coronary plaques. Fifty-nine consecutive patients (stable/unstable angina 34/21) were enrolled. Mean computed tomographic (CT) density (Hounsfield units) of noncalcified coronary plaques (n = 80) was compared with a relative volume of each plaque component (fibrous, fibrofatty, calcium, and necrotic core) analyzed by virtual histology. Mean heart rate during MDCT was 58 ± 9 beats/min. There was a negative correlation between mean CT density and the necrotic core (r = −0.539, p <0.001) and a positive correlation between mean CT density and the fibrotic tissue component (r = 0.571, p <0.001). Mean CT density of the plaques with a <10% necrotic core was significantly higher than that of a ≥10% necrotic core (93.1 ± 37.5 vs 41.3 ± 26.4 HU, p <0.001). However, overlapping of mean CT densities between plaques with a <10% necrotic core and those with a ≥10% necrotic core was found. In conclusion, mean CT density of noncalcified coronary plaques measured by 64-slice MDCT may depend on the relative volumes of the necrotic core and fibrotic component. Sixty-four–slice MDCT may have the potential for determining composition of noncalcified coronary plaques, which needs further studies for clinical application.