Administration of unfractionated heparin with prolonged fasting could reduce physiological 18F-fluorodeoxyglucose uptake in the heart

Background: The physiological uptake of 18F-fluorodeoxyglucose (FDG) in the heart often interferes with the accurate diagnosis of inflammatory cardiac diseases (CDs). Unfractionated heparin (UFH) administration may suppress its uptake through the alteration of myocardial metabolism. Purpose: To clarify the effectiveness of UFH administration to suppress the physiological FDG uptake in the heart. Material and Methods: The physiological FDG uptake in the heart was compared among 178 patients who fasted less than 18 h, 37 patients who fasted more than 18 h, and 64 patients who fasted more than 18 h and were administered UFH (UFH-CD group) prior to FDG PET/CT. Free fatty acid (FFA), triglyceride, insulin, and blood glucose levels were measured after UFH administration. Myocardial FDG uptake was evaluated by visual assessment and on the basis of maximum standardized uptake value (SUV_max).Results: In the UFH-CD group, the FFA level increased 15 min after UFH administration (P<0.01). Blood glucose and insulin levels remained unchanged (PNS). FDG physiological uptake was observed in 69% of the patients who fasted less than 18 h, 38% of the patients fasted more than 18 h, and 22% of the UFH-CD group (P<0.01 for trend). SUVmax decreased in the UFH-CD group compared with the patients who fasted less than 18 h (P<0.01) and the patients who fasted more than 18 h (P0.029). Conclusion: UFH administration and fasting more than 18 h could effectively suppress FDG physiological uptake in the heart and can be a useful method of detecting inflammatory CDs and tumors.