Characterization of coronary atherosclerotic plaques by multidetector computed tomography

Multidetector computed tomography (MDCT) provides 3-dimensional noninvasive visualization of the coronary arterial tree. We compared MDCT with intravascular ultrasound (IVUS) for assessment of severity of coronary artery stenosis and composition of atherosclerotic plaques in 40 patients (32 men; mean age 52 years, range 33 to 86) with documented coronary artery disease. Cross-sectional images obtained at 10-mm increments were assessed for percent decrease in luminal area. Atherosclerotic plaques were classified by IVUS as soft, fibrous, or calcified. On the matched multidetector computed tomograms, regions of interest of 1 to 3 mm in diameter were placed inside each plaque, and tissue contrast was measured in Hounsfield units. Obstructive coronary artery disease was found in 50 segments by IVUS and 57 segments by MDCT. Sensitivity for detecting obstruction >50% was 86.0% (95% confidence interval 72.6 to 93.7) and specificity was 90.2% (95% confidence interval 83.9 to 94.4). In total, 276 plaques were examined by IVUS and MDCT. There were 188 soft plaques (68.2%), 45 fibrous plaques (16.2%), and 43 calcified plaques (15.5%). Multidetector computed tomographic tissue contrast of soft, fibrous, and calcified plaques were 71.5 ± 32.1, 116.3 ± 35.7, and 383.3 ± 186.1, respectively (p <0.001). Using a cut-off value of 185 HU, 273 of 276 plaques (99%) were correctly classified as calcified or noncalcified plaques. Using a cut-off value of 88 HU, 192 of 233 noncalcified plaques (82%) were correctly classified as fibrous or soft plaques. In conclusion, our data indicate that MDCT can provide important information concerning the composition of atherosclerotic plaques in addition to detecting luminal obstruction.