Abstract: Objective: To evaluate diagnosis accuracy for coronary stenosis from diameter measurements of different severities of stenosis by using gemstone spectral imaging（GSI）. Methods: Totally 3 different coronary artery models（internal diameter: 3.00 mm）with different severities of stenosis (residual lumen diameter ratio : 75%, 50%, 25%,) were placed in a pulsating cardiac phantom （ALPHA 1-VT PC, Fuyo Corporation, Japan）. The coronary phantom was scanned in 2 models: gemstone spectral imaging （GSI） and Axial scan model（AXIAL）. All the spectral imaging data were analyzed by using GSI viewer to reconstruct the VMS images （40～140keV by 10 keV interval） and AXIAL. CT values (HU) of the remained lumen from all different stenositc lumens were measured. The residual rate (%) was calculated by dividing the diameters of the remained lumen to normal lumen on the reformatted short axial images. One-Way ANOVA was used to compare the residual rate measurement difference between VMS. Student t test was used to compare the residual rate measurement difference between VMS and AXIAL. Bland-Altman test was used to compare the measured residual rates and the gold standard. P＜0.05was considered as significant differences. Results: There were no significant differences among the VMS diameter measurements（P>0.05）. From student t test, only significant difference between 70keV VMS and AXIAL was found on 50% stenosis（t =4.617，P＜0.042）. From the Bland-Altman test, residual rate measurement from 70keV VMS was more accurate than AXIAL by taking the real model stenosis rate as gold standard（t =14.560，P＜0.000）. In the mild severity of stenosis (75% of the residual lumen), GSI slightly underestimated the degree of stenosis, while AXIAL slightly overestimated the stenosis. The accuracy of the GSI measurement was slightly higher than that of AXIAL. Conclusion: VMS image (70keV) showed more accurate than AXIAL images on both diameter measurement and evaluation of the coronary stenosis rate.

Key words: Spiral cone-beam computed tomography, Coronary disease, coronary stenosis, CT angiography, Dual energy imaging