Study Of¹⁸F-NaF PET/MR In High Risk Plaque Of Coronary Artery

PART1 A comparison of Dixon based and CT attenuation correction in the application of cardiac PETObjective:To evaluate the accuracy of MRI-Dixon attenuation correction?AC?methods in the cardiac PET/MR examination in comparing with PET/CT.Methods:23 patients were randomly selected for analysis in this study.All subjects underwent whole-body 18F-FDG PET/CT scan for oncological indications and followed by cardiac PET/MR scan.PET/CT and PET/MR data were processed in Cedars software.Polar maps were normalized to 100%peak activity and the segmental relative radiotracer uptake was computed using a 20-segment model for the left ventricle using AHA model.18F-FDG metabolites,in terms of the percentage.of average standardized uptake value?SUV?to the highest SUV in left ventricle,were analyzed in each segment Pair-t test was used to compare the metabolic difference between PET/CT and PET/MR data.Pearson correlation and Bland-Altman?BA?analysis were used to compare the correlation and consistency between PET/CT and PET/MR data,respectively.Results:Excellent correlations were found for regional SUV percentage relative to highest SUV in left ventricle between PET/CT and PET/MR?n=460 segments in 23 patients;r=0.891?with Bland-Altman limits of agreement?-9.49%to+11.95%?.Conclusion:Relative myocardial 18F-FDG uptake percentages obtained from MRI-based attenuation corrected 18F-FDG PET is highly comparable to standard CT-based attenuation corrected 18F-FDG PET.Compared to PET/CT,PET/MR shows a very small underestimation of relative myocardial FDG uptake percentages,suggesting diagnostic value for clinical routine.Part2 Preliminary study of PET/MR¹⁸F-NaF imaging combined with CATCH sequence of high-risk plaqueIntroduction:18F-NaF PET is a promising non-invasive imaging method to identify ruptured or high-risk coronary plaque with active calcification.Its CMR counterpart,coronary atherosclerosis T1-weighed characterization with integrated anatomical reference,CATCH,has the capability to detect high-risk plaque features such as hemorrhage.The combination of both techniques from a PET/MR scan may provide unique complementary information regarding the disease status.This paper preliminarily investigated the value of PET/MR 18F-NaF combined with CATCH imaging technology in the diagnosis of high-risk coronary plaque.Methods:10 patients with clinically suspected acute coronary syndrome underwent cardiac 18F-NaF combined with CATCH and Gd MR delayed enhancement?LGE?gated imaging.All patients underwent coronary angiography within 1 day after PET/MR examination.CATCH bright-blood images can provide anatomical localization for PET images and dark-blood images.According to the location of the plaque which was defined by coronary angiography,plaque to myocardium signal intensity ratio?PMR?of the lesion was measured in CATCH dark-blood images.Focal 18F-NaF uptake of each lesion was quantified using maximum tissue-to-background ratio?TBRmax?.Rank sum test was used to compare the statistical difference of PMR and TBRmax between the culprit and non-culprit lesions.Pearson correlation analysis was performed between PMR and TBRmax..Results:All of the 10 patients were successfully examined.A total of 45 plaques were identified in all patients in coronary angiography.According to the clinical symptoms,ECG,echocardiography,coronary angiography and delayed myocardial enhancement,15 culprit vessels were identified and 18 plaques were found.The plaques in culprit vessels showed a higher PMR than the plaques in non-culprit vessels?1.24±0.37 versus 0.76±0.21,P<0.0001?.The plaques in culprit vessels showed a higher TBRmax than the plaques in non-culprit vessels?1.10±0.31 versus 0.80±0.29,P<0.05?.There was a weak correlation between PMR and TBRmax?r=0.36,P=0.03?.Conclusions:We demonstrated that PET/MR 18F-NaF combined with the CATCH technique is a feasible noninvasive method to provide multi-parametric evaluation of coronary plaque.PMR derived from CATCH and TBRmax derived from 18F-NaF PET can be used as diagnostic biomarkers for high-risk plaque.TBRmax is weakly correlated with PMR suggesting a potentially different pathological information rendered by the two modalities.A larger cohort is needed to further elucidate their overlap and difference.