Objective: We evaluated the ability of 64-slice multidetector computed tomography (MDCT)-derived plaque parameters to detect and quantify coronary atherosclerosis, using intravascular ultrasound (IVUS) as the reference standard. Methods: In 32 patients, IVUS and 64-MDCT was performed. The MDCT and IVUS datasets of 44 coronary arteries were co-registered using a newly developed fusion technique and quantitative parameters were derived from both imaging modalities. The threshold of >0.5mm of maximum wall thickness was used to establish plaque presence on MDCT and IVUS. Results: We analyzed 1364 coregistered 1-mm coronary cross-sections and 255 segments of 5-mm length. Compared with IVUS, 64-MDCT enabled correct detection in 957 of 1109 cross-sections containing plaque (sensitivity 86%). In 180 of 255 cross-sections atherosclerosis was correctly excluded (specificity 71%). On the segmental level, MDCT detected 213 of 220 segments with any atherosclerotic plaque (sensitivity 96%), whereas the presence of any plaque was correctly ruled out in 28 of 32 segments (specificity 88%). Interobserver agreement for the detection of atherosclerotic cross-sections was moderate (Cohen's kappa coefficient K = 0.51), but excellent for the atherosclerotic segments (K = 1.0). Pearson's correlation coefficient for vessel plaque volumes measured by MDCT and IVUS was r = 0.91 (p < 0.001). Bland-Altman analysis showed a slight non-significant underestimation of any plaque volume by MDCT (p = 0.5), with a trend to underestimate noncalcified and overestimate mixed/calcified plaque volumes (p = 0.22 and p = 0.87 respectively). Conclusion: MDCT is able to detect and quantify atherosclerotic plaque. Further improvement in CT resolution is necessary for more reliable assessment of very small and distal coronary plaques. (C) 2011 Elsevier Ireland Ltd. All rights reserved.