||High Dose Steroid Therapy Increases Physiological Myocardial Uptake due to Metabolic Shift in Evaluation of the Cardiac Sarcoidosis with FDG PET/CT
Manabe, Osamu ,
Yoshinaga, Keiichiro ,
Ohira, Hiroshi ,
Noriko, Oyama-Manabe ,
Tsujino, Ichizo ,
Nishimura, MasaharuTamaki, Nagara
Background: 18F-fluorodeoxyglucose (FDG) PET/CT plays an important role to detect active cardiac involvement and to evaluate the response to steroid therapy in cardiac sarcoidosis (CS). The long fasting with low-carbohydrate diet (LCD) is useful preparation for suppressing physiological myocardial FDG uptake. However, the steroid therapy interferes with glucose metabolism and increases insulin resistance, therefore it may affect myocardial FDG uptake. Limited studies evaluated the effects of the steroid therapy on physiological FDG uptake. The purpose of the current study was to examine the effect of the steroid therapy on physiological cardiac FDG uptake. Thus, we compared FDG PET/CT and plasma free fatty acid (FFA) level among before (1st scan) and after the steroid therapy (2nd scan; at 30mg/day, 3rd scan; at maintenance dose). Methods: Fifteen CS patients (57.1 ± 15.8 years old, 6 male) fasted over 18 hours with LCD the last night prior to the FDG PET/CT scan. Sixty minutes after FDG administration, a static scan was performed. The myocardial FDG uptake was defined as physiological or positive pattern based on the MRI and myocardial perfusion images. Results: There was no patient who showed the physiological uptake at the first and 3rdstudy. However, 3 of the 15 patients (20.0 %) showed the physiological uptake at the 2nd scans under high dose steroid therapy. The fasting time and injection dose were not significantly different between the two scans. FFA was significantly lower in 2nd study(1st; 895.0 ± 296.2 vs. 2nd; 702.1 ± 299.6 vs. 3rd; 916.4 ± 246.5 μEq/L, p < 0.05) compared to the 1st and 3rd scans. In particular at the 2nd scans, the FFA level of the patients with physiological uptake was significantly lower than those without physiological uptake (799.2 ± 257.3 vs 346.0 ± 100.6 μEq/L, p = 0.02).Conclusion:During the high dose steroid therapy, long-fasting and LCD preparation was not able to perfectly suppress physiological myocardial FDG uptake. The fasting FFA level was lower during high steroid therapy. The cardiac metabolic shift may contribute to increasing physiological myocardial FDG uptake.