Additional Value Of On-demand Spectral Coronary CT Angiography In The Assessment Of Coronary Artery Disease

Objective:On-demand spectral coronary CT angiography for every patient is an original feature for dual-layer detector CT.The aim of this study is to assess the additional value that it brings coronary artery stenosis as well as myocardial perfusion evaluation.Material and Methods:19 consecutive patients(4 female,15 male;mean age 65± 12 years)with coronary heart disease were scanned using Philips IQon Spectral CT followed with SPECT myocardial perfusion scanning within a week to confirm the myocardial perfusion defect(7 under rest SPECT MPI only and 7 with under stress-rest SPECT MPI and 5 under stress SPECT MPI only),We divided these patients into two groups,14 patients underwent rest SPECT and 12 patients underwent stress SPECT.Z-effective map,iodine density map,monochromatic 40keV image and conventional CT image were reconstructed from spectral imaging data simultaneously.Detection of myocardial defects based on these images were evaluated quantitatively and qualitatively compared with SPECT as a reference.And the diagnostic performance of each method was analyzed using Receiver-operating characteristic(ROC)curve.Results:In all 19 patients,coronary artery stenosis(>50%)were found for 63 out of 301 segments confirmed by CCTA?myocardial perfusion defect were found for 65 out of 304 sections confirmed by SPECT.As rest SPECT a reference standard,quantitative assessment found that there were all statistical differences in differentiating hypo-perfusion area and normal myocardium for both spectral images and conventional CT image,the average value of iodine density images was about 1.88 ±0.52 mg/mL vs.0.75±0.40mg/mL(p<0.001),the average value of Z-effective map was about 8.50±0.28 vs.7.82±0.27(p<0.001),the average value of Mono 40keV was about 195.95±40.28 vs.95.75HU±46.83HU(p<0.001),the average value of conventional CT image xwas about 91.25± 14.12HU vs.52.51 ±24.89HU(p<0.001);As stress SPECT a reference standard,quantitative assessment also found that there were all statistical differences in differentiating hypo-perfusion area and normal myocardium for both spectral images and conventional CT image.the average value of iodine density images was about 1.88±0.52 mg/mL vs.0.75±0.40mg/mL(p<0.001),the average value of Z-effective map was about 8.39±0.41 vs.7.87±0.44(p<0.001),the average value of Mon0 40keV was about 184.43 ±65.09 HUvs.1 05.14 ±63.58HU(p<0.001),the average value of conventional CT image was about 85.27 ± 26.24HU vs.59.54 ±27.69HU(p<0.001).But the ROC curve analysis showed that the diagnostic performance of iodine density map in the assessment of myocardial defect were superior to those of conventional CT images in rest or stress SPECT condition.Conclusion:Spectral CT images,especially the iodine density map,are superior to the conventional CT images in the assessment of myocardial defect.This "one-stop" cardiac solution revealed not only coronary artery structure but also myocardial perfusion condition,which enriches the clinical diagnostic information for every patent in every CT cardiac examination.