Several models for the quantitative analysis of myocardial blood flow (MBF) at stress and rest and myocardial flow reserve (MFR) with 13 N-ammonia myocardial perfusion PET have been implemented for clinical use. We aimed to compare quantitative results obtained from 3 software tools (QPET, syngo MBF, and PMOD), which perform PET MBF quantification with either a 2-compartment model (QPET and syngo MBF) or a 1-compartment model (PMOD). Methods: We considered 33 adenosine stress and rest 13 N-ammonia studies (22 men and 11 women). Average age was 54.5 6 15 y, and average body mass index was 26 6 4.2. Eighteen patients had a very low likelihood of disease, with no chest pain, normal relative perfusion results, and normal function. All data were obtained on a PET/CT scanner in list mode with CT attenuation maps. Sixteen dynamic frames were reconstructed (twelve 10-s, two 30-s, one 1-min, and one 6-min frames). Global and regional stress and rest MBF and MFR values were obtained with each tool. Left ventricular contours and input function region were obtained automatically in system QPET and syngo MBF and manually in PMOD. Results:The flow values and MFR values were highly correlated among the 3 packages (R 2 ranging from 0.88 to 0.92 for global values and from 0.78 to 0.94 for regional values. Mean reference MFR values were similar for QPET, syngo MBF, and PMOD (3.39 6 1.22, 3.41 6 0.76, and 3.66 6 1.19, respectively) by 1-way ANOVA (P 5 0.74). The lowest MFR in very low likelihood patients in any given vascular territory was 2.25 for QPET, 2.13 for syngo MBF, and 2.23 for PMOD. Conclusion: Different implementations of 1-and 2-compartment models demonstrate an excellent correlation in MFR for each vascular territory, with similar mean MFR values.

Background Hybrid PET/CT allows acquisition of cardiac PET and coronary CT angiography (CCTA) in one session. However, PET and CCTA, are acquired with differing breathing protocols and require software registration. We aimed to validate automatic correction for breathing misalignment between PET and CCTA acquired on hybrid scanner. Methods Single-session hybrid PET/CT studies of rest/stress 13N-ammonia PET and CCTA in 32 consecutive patients were considered. Automated registration of PET left ventricular (LV) surfaces with CCTA volumes was evaluated by comparison to expert manual alignment by 2 observers. Results The average initial misalignment between the position of LV on PET and CCTA was 27.2±11.8mm, 13.3±11.5mm, and 14.3±9.1mm in x, y, and z axes on rest, and 26.3±10.2mm, 11.1±9.5mm, and 11.7±7.1mm in x, y, and z axes on stress. The automated PET-CCTA co-registration had 95% agreement as judged visually. Compared to expert manual alignment, the translation errors of the algorithm were 5.3±2.8mm (rest) and 6.0±3.5mm (stress). 3D visualization of combined coronary vessel anatomy and hypoperfusion from PET could be made without further manual adjustments. Conclusion Software co-registration of CCTA and PET myocardial perfusion imaging on hybrid PET/CT scanners is necessary, but can be performed automatically, facilitating integrated 3D display on PET/CT.

Dyslipidemic patients show endothelial dysfunction measured with (13)N-ammonia PET. Treatment with ezetimibe/simvastatine was effective improving the lipid profile as well as the endothelial function of these patients. PET may be a useful tool to monitor vascular reactivity and regression/progression of coronary atherosclerosis after pharmacologic interventions.

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