CT angiography in highly calcified arteries: 2D manual vs. modified automated 3D approach to identify coronary stenoses

Background: Two-dimensional axial and manually-oriented reformatted images are traditionally used to analyze coronary data provided by multidetector-row computed tomography angiography (MDCTA). While apparently more accurate in evaluating calcified vessels, 2D methods are time-consuming compared with automated 3D approaches. The purpose of this study was to evaluate the performance of a modified automated 3D approach (using manual vessel isolation and different window and level settings) in a population with high calcium scores who underwent coronary half-millimeter 16-detector-row CT angiography (16×5-MDCTA). Methods: ECG-gated 16×0.5-MDCTA (16×0.5 mm cross-sections, 0.35×0.35×0.35 mm³ isotropic voxels, 400 ms rotation) was performed after injection of iopamidol (120-ml, 300 mg/ml) in 19 consecutive patients (11 male, 62 ± 10 years-old). Native arteries were independently evaluated for ≥50%-stenoses using both manual 2D and modified automated 3D approaches. Stents and bypass grafts were excluded. Conventional coronary angiography was visually analyzed by 2 observers. Results: Median Agatston calcium score was 434. Sensitivities, specificities, positive and negative predictive values for detection of ≥50% coronary stenoses using the 2D and modified 3D approaches were, respectively: 74%/63%, 76%/80%, 45%/34%, and 91%/93% (p=NS for all comparisons). Overall diagnostic accuracies were 75 and 78%, respectively (p=NS). Uninterpretable vessels were, respectively: 37% (77/ 209) and 35% (73/209) - p=NS. Time to analyze a single study was 160 ± 23 and 53 ± 11 min, respectively (p<0.01). Conclusions: This modified automated 3D approach is equivalent to and significantly less time consuming than the traditional manual 2D method for evaluation of ≥50%-stenoses by 16×0.5-MDCTA in native coronary arteries of patients with high calcium scores.