Edgar Romero

Endothelial Dysfunction in Systemic Lupus Erythematosus: Evaluation with 13N-Ammonia PET

Systemic lupus erythematosus (SLE) affects multiple organs and systems, severely involving the cardiovascular system. The aim of this study was to evaluate the presence of endothelial dysfunction with 13N-ammonia PET in asymptomatic SLE patients. Methods: We enrolled 16 women with SLE and 16 healthy women. Myocardial blood flow (MBF) was quantified in a 64-slice PET/CT scanner at rest, during a cold pressor test (CPT), and during stress. Endothelium-dependent vasodilation index, %ΔMBF, and myocardial flow reserve (MFR) were calculated. Results: There were 16 women in the SLE group (mean age ± SD, 31.4 ± 8.3 y) and 16 women in the healthy control group (31.5 ± 11.1 y). Mean endothelium-dependent vasodilatation index and %ΔMBF were significantly lower in SLE patients (1.18 ± 0.55 vs. 1.63 ± 0.65, P = 0.04, and 18 ± 55 vs. 63 ± 65, P = 0.04, respectively). MFR was also lower in the SLE group (2.41 ± 0.59 vs. 2.73 ± 0.77, P = 0.20). Conclusion: SLE patients who are free of active disease present abnormal coronary flow and endothelial dysfunction. It is necessary to develop and intensify treatment strategies directed to CAD in SLE patients.

Functional Impact of Coronary Stenosis Observed on Coronary Computed Tomography Angiography: Comparison with 13N-Ammonia PET

BACKGROUND AND AIMS We undertook this study to evaluate the functional impact of coronary abnormalities in patients with suspected coronary artery disease (CAD) by means of integrated positron emission tomography (PET) and coronary computed tomography angiography (CCTA) scan obtained on a hybrid state-of-the-art PET/CT scanner. METHODS We studied 29 consecutive, patients with a clinically suspected intermediate risk for CAD, using a hybrid PET/CT 64 slice scanner. During a single scanning session, CCTA was performed for coronary anatomy evaluation, and a rest/adenosine stress (13)N-ammonia PET was performed for myocardial perfusion assessment in 3D mode with CT attenuation correction. RESULTS Twenty four (82.7%) patients had atherosclerosis detected by CCTA; 15 patients had significant (≥50%) coronary stenoses and all 15 patients showed ischemia by PET; moreover, 10/15 patients had a Summed Stress Score >12.20/24 and 83.3% patients with atherosclerosis detected by CCTA showed ischemia by PET. Two of five patients with normal coronary arteries showed ischemia by PET. CCTA agreement in positive identification of PET ischemia was 91% and agreement in ruling out ischemia was 43%; PET agreement in detecting CCTA atherosclerosis was 83%, and agreement in ruling it out was 60%. CONCLUSIONS We found a strong relation between significant coronary stenosis identified by CCTA and ischemia by PET. However, in cases with low-grade stenosis, PET scan can assess the functional significance of atherosclerotic abnormalities.