Morphological And Functional Diagnosis Of Coronary Artery Disease By Cardiac CT

Purpose:1)To investigate the diagnostic performance of coronary CT angiography derived from dynamic CT myocardial perfusion imaging(CCTA_CT-MPI)by third-generation dual-source CT with reference to invasive coronary angiography（ICA）.2)To investigate the association between perivascular fat attenuation index（FAI）,high-risk plaque features and serum level of high sensitive C-reactive protein（hs-CRP）.3)To investigate the serial change of FAI as quantified by CCTA after statin treatment.Methods:1)Patients with acute myocardial infarction and those who received successful reperfusion treatment were prospectively enrolled.Emergent ICA findings were used as the reference standard to assess the diagnostic performance of CCTA _CT-MPI for detection of significant coronary stenosis（diameter stenosis≥50%）.The radiation dose as well as images quality of CCTA_CT-MPI was also assessed.2)Consecutive patients with intermediate pre-test probability of CAD,who were referred for coronary CT angiography（CCTA）,were included.High-risk plaque features,such as low attenuation plaque（LAP）,positive remodeling（PR）,napkin-ring sign（NRS）and spotty calcification,were assessed by CCTA.Lesion specific perivascular FAI was also measured for all plaques located on major epicardial vessels with diameter≧2mm.Laboratory test results,including hs-CRP,were recorded.3)Patients with intermediate pre-test probability of CAD,who were referred for baseline CCTA to rule out obstructive disease and then received optimal medical treatment（OMT）,were included.Plaque type,traditional plaque morphological features and high-risk plaque features were assessed by baseline and follow-up CCTA.Lesion specific perivascular FAI at baseline and follow-up CCTA was also measured for all plaques located on major epicardial vessels with diameter≧2mm.Results:1)Twenty-six patients with 352 segments were ultimately included for analysis.The mean radiation dose of CCTA _CT-MPI generated from dynamic CT-MPI was3.2±1.1 m Sv.Overall,93.5%of total segments were interpretable（Likert score 2-4）whereas 6.5%segments were non-diagnostic（Likert score 1）.Twenty-two patients with84 segments were diagnosed by CCTA_CT-MPI as having≥50%stenosis whereas 268segments had no obstructive stenosis.Compared to ICA findings,the overall diagnostic accuracy of CCTA_CT-MPI of patient-based and vessel-based as well segment-based analysis was 92.3%,83.6%,and 85.8%respectively.As shown by ROC analysis,the AUC of CCTA_CT-MPIfor detection of≥50%stenosis was 0.833 on a per-patient level,0.843 on a per-vessel level,and 0.822 on a per-segment level.2)199 patients with 260lesions were finally included.NRS and LAP were more commonly present in the group with elevated hs-CRP（35.9%VS.19.4%and 14.1%VS.2.6%,both p<0.05）and more severe stenosis extent was also noted for this group.However,there was no significant difference between the elevated hs-CRP and normal hs-CRP group with respect to other CT parameters,such as lesion length,PR,spotty calcification and focal calcium score.Perivascular FAI failed to show significant difference between the two groups（-69.8±10.3HU vs.-70.0±12.0HU,p=0.953）and there was poor correlation between perivascular FAI and hs-CRP measurements（r=-0.04,p=0.510）.3)108 patients with144 lesions were finally included in the study.The FAI value was significantly smaller after statin treatment（-69.83±9.14 HU vs.-72.05±8.87 HU,p<0.001）.A significant reduction of the FAI value was found in both non-calcified plaque and mixed plaque subgroups（-68.02±8.52HU vs.-71.50±8.05 HU,p<0.001 and-70.53±8.95 HU vs.-72.76±8.98 HU,p=0.014 respectively）,but this difference did not remain statistically significant in calcified group（-70.64±9.74 HU vs.-71.66±9.87 HU,p=0.258）.Conclusions:1)CCTA derived from dynamic CT-MPI was able to accurately diagnose obstructive coronary stenosis with reference to ICA.2)LAP and NRS are more commonly present in CAD patients with elevated level of hs-CRP.However,perivascular FAI failed to show such correlation with serum level of hs-CRP.3)Lesion-specific perivascular FAI was reduced at mid-term follow-up after statin treatment.This effect was mainly observed for non-calcified and mixed plaques.