Assessing the Clinical Value of Myocardial Perfusion SPECT in Cardiac Sarcoidosis with Diffuse Myocardial F-FDG Uptake.

: Myocardial F-fluorodeoxyglucose (F-FDG) uptake is a sign of active inflammation in patients with cardiac sarcoidosis (CS) under the correct circumstance. However, even under the proper preparation, diffuse myocardial F-FDG uptake is frequently observed in the failing heart and misleads the CS disease activity. The aim of this study was to establish the diagnostic value of resting myocardial perfusion single photon emission computed tomography (SPECT) for assessing CS disease activity in patients with diffuse myocardial F-FDG uptake. : We examined 39 patients with either histologically or clinically proven CS. All patients underwent F-FDG positron emission tomography (PET) and resting Tc-SPECT. The presence of perfusion-metabolic mismatch was evaluated with generating polar maps of F-FDG PET and Tc-SPECT images. : Increased myocardial F-FDG uptake was observed in 33 (85%) of 39 patients. Focal F-FDG uptake was detected in 16 patients and diffuse F-FDG uptake was seen in 17 patients. Brain natriuretic peptide (BNP) levels were significantly higher in patients with diffuse F-FDG uptake than those with focal F-FDG uptake (p=0.002). With comparing polar maps of F-FDG PET and Tc-SPECT images, 8 of 16 patients with diffuse F-FDG uptake and myocardial perfusion defects demonstrated perfusion-metabolic mismatch which represented active inflammatory lesions in CS. : Simultaneous evaluation of myocardial F-FDG PET and Tc-SPECT by polar map analysis provides more relevant information for assessing disease activity in CS than F-FDG PET images alone. Perfusion-metabolic mismatch might indicate latent active inflammation in CS patients with diffuse myocardial F-FDG uptake, who had advanced heart failure.