Abstract 4214: Detection, Quantification and Characterization of Coronary Atherosclerotic Plaque by Dual-Source CT - A Comparison to Intravascular Ultrasound
We attempt to evaluate Dual source CT (DSCT) for detection, quantification and characterization of coronary plaque, having intravascular ultrasound (IVUS) as the reference standard. We prospectively enrolled 21 patients who underwent DSCT (Definition, Siemens Medical Solutions, Forchheim, Germany) and IVUS (mechanical 40 MHz system, Boston Scientific Corp. Boston, MA) as part of a research protocol, who were scheduled for clinically indicated invasive angiography. Coronary CT data sets were co-registered to IVUS by an experienced study coordinator and each obtained slice was scored by two blinded observers for presence and type of plaque. Quantitative measurements were obtained, including cross-sectional vessel area, lumen area, plaque area and volume. Mean and standard deviation of Hounsfield units (HU) were recorded for plaque when present. Overall, 23 coronary lesions encompassing 220 cross-sections in 21 patients (61±10 years, 13 male) were analyzed by DSCT and IVUS. Overall sensitivity, specificity, PPV, NPV for plaque detection by DSCT using IVUS as a gold standard, was 98%, 93%, 98%, and 91%, respectively. The Cohen’s Weighted kappa coefficient for plaque detection between two observers was κ=0.78, with 92% of agreement. Spearman’s correlation coefficients were r=0.86, r=0.87 and r=0.69 for cross sectional vessel area, lumen area and plaque area, respectively. DSCT had an excellent correlation with IVUS for plaque volume quantification (r=0.88, p<0.0001; 73±51mm3 and 68±47 mm3, respectively) with small overestimation (bias=5±17mm3). The coefficient of variability for two blinded observers to determine plaque volume was 22.7%. The mean CT density of lipid-rich plaque was 78±35HU, fibrous plaque 119±46HU and calcified plaque 644±408HU. Improvements in temporal resolution with DSCT led to better detection and quantification of coronary plaque as compared to prior CT generations, resulting in decrease in the coefficient of variability for plaque volume quantification. Our results, however, demonstrate the difficulty in reliably differentiating non-calcified plaque components by DSCT.