18 F-FMISO PET/CT detects hypoxic lesions of cardiac and extra-cardiac involvement in patients with sarcoidosis.

Background: ¹⁸ F-fluoromisonidazole (FMISO) is a hypoxia positron emission tomography (PET) tracer. Here, we evaluated cardiac and extra-cardiac sarcoidosis using both FMISO and ¹⁸ F-fluorodeoxyglucose (FDG) PET/CT in a prospective cohort of patients with sarcoidosis.
Methods: Ten consecutive sarcoidosis patients with suspected cardiac involvement were prospectively enrolled. Each patient fasted overnight (for ≥ 18 hours) preceded by a low-carbohydrate diet before FDG PET/CT but not given special dietary instructions before the FMISO PET/CT scan. We visually and semiquantitatively assessed the uptakes of FMISO and FDG using the maximal standardized uptake value (SUV _max ). The metabolic volume (MV) of FDG was calculated as the volume within the boundary determined by the threshold (mean SUV of blood pool × 1.5).
Results: Nine patients showed focal FDG uptake in the myocardium and were diagnosed with cardiac sarcoidosis. Among the patients with extra-cardiac lesions, FDG uptake was seen in 8 lymph nodes and 3 lung lesions. FMISO uptake was seen in the 7 cardiac (77.8%) and 6 extra-cardiac (54.5%) lesions. None of the patients showed physiological FMISO uptake in the myocardium. The SUV _max values of the lesions with FMISO uptake were higher than those of the lesions without FMISO uptake in both the cardiac (SUV _max : 9.9, IQR: 8.4-10.0 vs 7.3, IQR: 6.3-8.2) and non-cardiac lesions (SUV _max : 17.6, IQR: 14.5-19.3 vs 6.1, IQR: 5.9-6.2; P = 0.006). The MV values of the lesions with FMISO uptake were significantly higher than those of the lesions without FMISO uptake (111.3, IQR: 78.3-135.7 vs 6.4, IQR: 1.9-23.3; P = 0.0009).
Conclusions: FMISO showed no physiological myocardial uptake and did not require special preparation. FMISO PET has the potential to detect hypoxic lesions in patients with sarcoidosis.
(© 2019. American Society of Nuclear Cardiology.)