OBJECTIVE: To evaluate a modified subtraction coronary computed tomography angiography (CCTA) technique with a two-breathhold approach in terms of image quality and stenosis grading of calcified coronary segments and in the detection of significant coronary stenosis in segments with severe calcification. MATERIALS AND METHODS: The institutional board approved this study, and all subjects provided written consent. A total of 128 patients were recruited into this trial, of which 32 underwent subtraction CCTA scans and invasive coronary angiography (ICA). The average Agatston score was 356 ± 145. In severely calcified coronary segments, the presence of significant (> 50%) stenosis was assessed on both conventional CCTA and subtraction CCTA images, and the results were finally compared with ICA findings as the gold standard. RESULTS: For severely calcified segments, the image quality in conventional CCTA significantly improved from 2.51 ± 0.98 to 3.12 ± 0.94 in subtraction CCTA (p < 0.001). In target segments, specificity (70% vs. 87%; p = 0.005) and positive predictive value (61% vs. 79%, p < 0.01) were improved using subtraction CCTA in comparison with conventional CCTA, with no loss in the negative predictive value. The segment-based diagnostic accuracy for detecting significant stenosis was significantly better in subtraction CCTA than in conventional CCTA (area under the receiver operating characteristic curve, 0.94 vs. 0.85; p = 0.03). CONCLUSION: This modified subtraction CCTA method showed lower misregistration and better image quality in patients with limited breathhold capability. In comparison with conventional CCTA, modified subtraction CCTA would allow stenosis regrading and improve the diagnostic accuracy in coronary segments with severe calcification.
Angiography ; Constriction, Pathologic ; Coronary Angiography ; Coronary Stenosis ; Humans ; Methods ; ROC Curve ; Sensitivity and Specificity

Objective:To investigate the clinical diagnostic value of subtraction coronary computed tomography angiography (CCTA) in patients with mild-moderate calcification of coronary artery (Agatston score＜400).Methods:A retrospective analysis of 69 cases with mild-moderate coronary calcification undergoing subtraction CCTA was performed.The image quality of calcified segments was evaluated using 4-point scale method.The stenosis of calcified segment was quantitatively assessed and divided into four different classifications (Ⅰ-Ⅳ).The time for quantitative assessment of calcified segments was recorded.Results:There were 113 calcified segments in 69 cases.The average image quality of calcified segments for conventional CCTA and subtraction CCTA was (3.4±0.6) and (3.8±0.4),respectively,with significant difference (P＜0.01).The Kappa coefficient used to describe the consistency of the stenosis grading in these two imaging methods was 0.77.The average time needed for quantitative assessment was (105 ± 44) s and (72 ± 44) s,respectively,with significant difference (P＜0.01).Conclusions:The two imaging methods have good consistency in evaluating stenosis grading in patients with mild-moderate calcification of coronary artery.Compared with conventional CCTA,subtraction CCTA can improve the image quality and reduce the time required for quantitative assessment of stenosis,thus improve the clinical efficiency.