Quantification of calcium volume by coronary CT compared to OCT

Background Coronary artery calcifications are frequently observed in patients referred for cardiac catheterization. Using OCT, the calcified volume can be determined. CT is a sensitive non-invasive tool to detect coronary artery calcifications and may be useful to guide percutaneous coronary intervention. Purpose The aim of the study was to investigate the accuracy of CT-derived calcium volume with OCT as a reference in patients undergoing PCI. Methods 66 calcified plaques (32 vessels) from 31 patients undergoing OCT-guided PCI with coronary CT angiography acquired as a standard of care were included. Coronary CT angiography and OCT images were matched using fiduciary points. Calcified plaques were reconstructed in three dimensions to calculate calcium volume. A Passing-Bablok regression analysis and the Bland-Altman method were used to assess agreement between imaging modalities. Results 27 left anterior descending arteries and 5 right coronary arteries were analyzed. Median calcium volume by CT angiography and OCT were 18.23 mm 3 [IQR 8.09, 36.48] and 10.03 mm 3 [IQR 3.6, 22.88]. The Passing-Bablok analysis showed a proportional difference without a systematic difference (Coefficient A 0.08, 95% CI: −1.37 to 1.21, Coefficient B 1.61, 95% CI: 1.45 to 1.84); with a mean difference of 9.69 mm3 (LOA −10.2 mm 3 to 29.6 mm 3). No significant differences were observed for MLA: median value for CT 2.84 mm2 [IQR 2.03, 3.74] and for OCT 2.55 mm2 [IQR 1.91, 4.43]. Conclusions Coronary CT angiography volumetric calcium evaluation overestimates calcium volume by 60% compared to OCT. Accounting for CT overestimation may allow for appropriate interpretation of calcific burden in the non-invasive setting. Coronary CT angiography may emerge as a tool to quantify calcium burden for invasive procedural planning. Calcium burden comparison CT vs OCT Funding Acknowledgement Type of funding source: None