Assessment of coronary plaque morphology by contrast-enhanced computed tomographic angiography: comparison with intravascular ultrasound.

BACKGROUND Computed tomographic (CT) angiography provides accurate noninvasive assessment for coronary artery stenosis. The ability of CT angiography to determine plaque morphology remains unclear. METHODS Twelve patients undergoing intravascular ultrasound for clinical indications underwent CT angiography for the evaluation of plaque morphology. Plaque morphology was classified as (1) soft, (2) fibrous, (3) fibrocalcific or (4) calcific. CT angiography data sets were evaluated for the presence and morphology of plaque in the coronary artery segments. The results were blindly compared with intravascular ultrasound results on a segment by segment basis using angiographic landmarks. RESULTS Fifty-nine coronary segments were analyzed; 10 segments were normal and 49 contained plaque. Plaque morphology by intravascular ultrasound was soft in 12 segments, fibrous in four, fibrocalcific in 29 and calcific in four. To determine coronary segments with any plaque, CT angiography had a sensitivity of 100% (49 of 49) and specificity of 90% (9 of 10). To determine plaque morphology as calcified (fibrocalcific and calcific) versus noncalcified (soft and fibrous), CT angiography had a sensitivity of 100% (33 of 33) and a specificity of 94% (15 of 16). Overall accuracy for CT angiography to determine plaque morphology was 92% (54 of 59). CT angiography density values (Hounsfield units, mean+/-standard deviation) were significantly different for each plaque morphology: soft 23+/-71, fibrous 108+/-79, fibrocalcific 299+/-112 and calcific 404+/-264 (P<0.0001). CONCLUSIONS CT angiography accurately characterized plaque morphology and may be a useful tool in noninvasive evaluation of plaque morphology during drug therapy trials.