Intense 68 Ga-OncoFAP Uptake as a New Promising Diagnostic Biomarker in Cardiac Sarcoidosis.

A 72-year-old man revealed typical findings of cardiac sarcoidosis on cardiovascular MRI. However, 18 F-FDG PET showed no hypermetabolism. Therefore, immunosuppression was not initiated. After 2 years, ventricular arrhythmias and heart failure worsened. 68 Ga-fibroblast activation protein inhibitor PET was initiated to evaluate potential adverse remodeling due to progressive myocardial fibrosis. A second 18 F-FDG PET still revealed no hypermetabolism, and the patient received an implanted cardioverter defibrillator after electrophysiological risk stratification. We present a case of intense fibroblast activation despite a missing 18 F-FDG uptake (mismatch).