We analyzed the frequency and characteristics of atherosclerotic plaques in the patients without coronary artery calcification (CAC) by the use of multidetector row CT (MDCT). In addition, we analyzed patients with negative CAC to guarantee the absence of coronary artery disease (CAD).

One hundred-ten patients with a suspicion of CAD and no CAC as detected on 16-slice and 64-slice MDCT were enrolled in this retrospective study. We analyzed the frequency of atherosclerotic plaques. For characterizing the atherosclerotic plaques, location, attenuation, volume, the degree of stenosis, and the remodeling index (RI) were analyzed.

Atherosclerotic plaques were detected in 8 patients (7.3%). The plaques were located in the right coronary artery (n=3), left anterior descending artery (n=3), and left main coronary artery (n=2). Attenuation, volume, stenosis and RI were 41.4±16.6 HU (range, 20.2 - 69.9 HU), 55±55 mm³ (range, 15-179 mm³), 40.7±16.3% (range,16.0-68.0%) and 1.35±0.13 (range, 1.16-1.50). Lipid rich plaque and significant stenosis were detected in 6 patients and in 2 patients, respectively.

Despite negative CAC as detected on MDCT, atherosclerotic plaque might have significant stenosis or lipid rich plaque. Therefore, negative CAC does not seem to guarantee the absence of CAD. Coronary CT angiography was recommended for patients with negative CAC.