Myocardial uptake of F-18-fluorodeoxyglucose in whole body positron emission tomography studies

PURPOSE: The objective of this study was to correlate the degree of myocardial fluorodeoxyglucose (FDG) uptake in routine oncology positron emission tomography (PET) studies with fasting blood sugar level (FBSL), fasting period (FP) and age of the patient. MATERIALS AND METHODS: Ninety-one patients (62 males and 29 females, age range: 7-78 years) with malignant diseases were included in the study. Whole body FDF-PET study was carried out after 1 h of intravenous injection of 296-370 MBq (8-10 mCi) F-18 FDG. Images were interpreted visually and patients were classified into four grades of myocardial uptake: No myocardial uptake = Grade 0; mild uptake = Grade 1; moderate uptake = Grade 2; and Marked uptake = Grade 3. Quantitative analysis was done by calculating Standardized uptake value (SUV(max)). Age, FBSL and FP were recorded. RESULTS: Thirty-seven (41%) patients showed no uptake in myocardium (Gr-0). Mean FP, FBSL and age was 14 h, 94.19 mg% and 44.3 years respectively. Eleven (12%) cases were rated as Grade 1, 27 (30%) as Grade 2 and 16 (17%) as Grade 3. The mean values of FP, FBSL and age were 12.9 h, 96.55 mg% and 43.54 years for Grade 1, 13.48 h, 87.11 mg% and 40.85 years for Grade 2 and 13.37 h, 86.56 mg% and 36.18 years for Grade 3 respectively. SUV(max) was found to vary between 1 and 22. It was observed that 47% (Grade 2 and 3) patients had significant cardiac FDG uptake in spite of blood sugar levels 71-125 mg%. CONCLUSION: The degree of myocardial FDG uptake did not show significant correlation with FBSL, FP or age of the patient. Perhaps the reason lies elsewhere like insulin levels, medical treatments, fat metabolism, and myocardium status or some unexplored factors.