Suppressing physiologic 18-fluorodeoxyglucose uptake in patients undergoing positron emission tomography for cardiac sarcoidosis: The effect of a structured patient preparation protocol

Objective: Myocardial positron emission tomography (PET) to detect cardiac sarcoidosis requires adequate patient preparation; however, in many cases physiologic myocardial ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake may not be adequately suppressed. We sought to evaluate the efficacy of a structured patient preparation protocol as recommended by the joint SNMMI/ASNC expert consensus document on the role of ¹⁸F-FDG PET/CT in cardiac sarcoid detection and therapy monitoring. The SNMMI/ASNC preparation protocol recommends at least two high-fat (> 35 g), low-carbohydrate (< 3 g) (HFLC) meals the day before testing followed by fasting for at least 4-12 hours. Methods: All unique PET scans performed for cardiac sarcoidosis before (group 1) and after (group 2) application of the new preparation protocol were included in the study. In group 1, patients were given a preparation protocol of HFLC meals with suggested meals examples, while patients in group 2 received detailed diet instructions, together with accepted and non-accepted meal examples along. In group 2, reinforcement of instructions by nursing staff and review of dietary log were performed prior to testing. All PET images were evaluated for suppression of physiologic myocardial ¹⁸F-FDG uptake. Results: Group 1 included 124 unique patients, and group 2 included 232 unique patients. There were no significant differences in baseline patient characteristics between the two groups. Suppression of physiologic myocardial ¹⁸F-FDG uptake was achieved in 91% of patients in group 2, compared to 78% of patients in group 1 (P <.001). A “diffuse” myocardial uptake pattern, indicating inadequate ¹⁸F-FDG suppression, was seen in 2% of studies in group 2 vs 12% in group 1 (P <.001). Conclusion: In this single-center study, application of a structured preparation protocol was highly successful in achieving suppression of physiologic myocardial ¹⁸F-FDG uptake in patients undergoing myocardial PET for cardiac sarcoidosis.