Optimal boundary detection method and window settings for coronary atherosclerotic plaque volume analysis in coronary computed tomography angiography: comparison with intravascular ultrasound

Abstract

OBJECTIVE: To evaluate optimal methodology for quantitative plaque volume analysis by coronary CT angiography (QCT).

METHODS: Fifty-one coronary artery segments were evaluated and contour measurements based on two different methods [(1) no gap, or (2) fixed 0.3-mm gap between inner and outer boundary] were compared with intravascular ultrasound (IVUS). In addition, three different window width (WW) and level (WL) settings [fixed (740/220) Hounsfield unit (HU), adjusted (155 % and 65 % of mean luminal intensity of the segment, and aorta adjusted (155 % and 65 % of mean luminal intensity of central aorta)] were used for semiautomated plaque volume analysis.

RESULTS: For boundary detection, the no gap method led to underestimation compared with IVUS (105.4?±?82.3 vs. 136.1?±?72.8 mm(3), p?<?0.001), while fixed 0.3-mm gap showed no difference between IVUS and QCT (136.1?±?72.8 vs. 139.8?±?93.9 mm(3), p?=?0.50). Comparison of the three different window settings demonstrated that the aorta adjusted setting underestimated (120.5?±?74.3 vs. 136.1?±?72.8 mm(3), p?=?0.003), while fixed setting showed the least mean difference compared with IVUS (3.8?±?39.8 mm(3), p?=?0.50).

CONCLUSION: For plaque volumetric assessment, optimal results were obtained with fixed 0.3-mm gap with fixed HU setting (740/220).

KEY POINTS: ? Quantitative plaque volume analysis by coronary CT angiography has recently emerged. ? Different boundary detection methods and window width and level settings were evaluated. ? Fixed 0.3-mm gap with fixed HU setting (740/220) afforded optimal results