Quantitative analysis of myocardial 18F-fluorodeoxyglucose uptake by PET/CT for detection of cardiac sarcoidosis

BackgroundImaging with fluorodeoxyglucose (FDG) PET/CT is used to diagnose patients with cardiac sarcoidosis (CS). However, its specificity is relatively low. We aimed to demonstrate that higher diagnostic specificity for CS can be obtained using quantitative methodology to analyze PET/CT.MethodsA total of 125 consecutive patients with suspected CS were enrolled in the study. After clinical assessment and cardiac imaging studies, the patients underwent FDG PET/CT imaging after eating a low-carbohydrate diet followed by an overnight fast lasting ≥ 18 h. For visual analysis, fusion and maximum intensity projection images were reviewed. For quantitative analysis, the maximum standardized uptake value (SUVmax) within the myocardium was obtained.ResultsOf the 92 patients who met study inclusion criteria, 37 were diagnosed with CS. Myocardial SUVmax was significantly higher in patients with CS compared with non-CS patients (9.5 ± 4.8 vs. 3.0 ± 1.7, p < 0.0001). The area under the curve by receiver operating characteristic analysis was 0.960 for SUVmax. Using a cut-off value of 4.0, the sensitivity was 97.3% and specificity was 83.6% for diagnosing CS, which is more accurate than visual analysis. Moreover, SUVmax was the only significant predictor of CS among 10 clinical and imaging variables. In 18 patients who received steroid therapy with a mean follow-up duration of 6.4 ± 5.2 months, SUVmax significantly decreased from 9.8 ± 4.2 to 5.5 ± 3.5 (p = 0.003).ConclusionWhen evaluated by quantification of myocardial SUVmax, FDG PET/CT imaging provides high sensitivity and specificity for diagnosing CS.