Diagnostic performance of 68Ga-DOTANOC PET/computed tomography in cardiac sarcoidosis: comparison with 18F-fluorodeoxyglucose PET/computed tomography and cardiac magnetic resonance

INTRODUCTION: Cardiac MRI (CMR) and PET aid in early diagnosis and follow-up of cardiac sarcoidosis. 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/computed tomography (CT) is a major criterion in diagnosing cardiac sarcoidosis disease activity and therapy response; however, requires stringent dietary modifications for suppressing myocardial uptake. 68 Ga-DOTANOC, targeting somatostatin receptors in sarcoid granulomas, maybe an alternative, showing minimal physiological myocardial uptake and not needing dietary modifications to suppress myocardial radiotracer activity. METHODOLOGY: This prospective study enrolled 23 patients, either biopsy-proven pulmonary sarcoidosis with suspected cardiac involvement or primary cardiac abnormalities with clinical and histopathological diagnosis from a systemic site. Patients underwent CMR, 13 N-NH 318 F-FDG PET/CT (post-low-carbohydrate, high-fat, high-protein diet), and 68 Ga-DOTANOC PET/CT. Patient-wise and cardiac-segment-wise analysis was done using Cohen's κ to assess intermodality agreement among three modalities. Mean maximum standardized uptake value (SUV max ) and target-to-background blood pool ratio (TBR) were calculated for positive lesions on 68 Ga-DOTANOC and 18 F-FDG PET/CT. RESULTS: 68 Ga-DOTANOC and CMR showed almost perfect segment-wise agreement [Cohen's κ : 0.88, 95% confidence interval (CI): 0.84-0.92, P = 0.004] and moderate patient-wise agreement (Cohen's κ : 0.51, 95% CI: 0.29-0.73, P = 0.003). 18 F-FDG PET/CT and CMR showed almost perfect segment-wise agreement (Cohen's κ : 0.80, 95% CI: 0.76-0.84, P = 0.004) and substantial patient-wise agreement (Cohen's κ : 0.77, 95% CI: 0.58-0.96, P = 0.001). Mean lesion SUV max and TBR were similar for 68 Ga-DOTANOC (6.6 ± 2.8 and 3.4 ± 1.4) and 18 F-FDG (9.0 ± 5.4 and 3.6 ± 1.2) (unpaired t -test, P = 0.16 for SUV max , P = 0.68 for TBR). CONCLUSION: 68 Ga-DOTANOC PET/CT shows promise as a complementary imaging modality for cardiac sacoidosis, with diagnostic performance comparable in many aspects to 18 F-FDG PET/CT and CMR. Further prospective studies are warranted to validate its role.