Potential clinical utility of ⁶⁸Ga-DOTATATE PET/CT for detection and response assessment in cardiac sarcoidosis

Somatostatin receptor is expressed in sarcoid granulomas, and preliminary clinical studies have shown that myocardial sarcoidosis can be identified on somatostatin receptor-targeted PET. We examined the potential clinical use of ⁶⁸Ga-DOTATATE PET/CT for diagnosis and response assessment in cardiac sarcoidosis compared to ¹⁸F-FDG PET/CT.

Eleven cardiac sarcoidosis patients with ¹⁸F-FDG PET/CT were prospectively enrolled for cardiac ⁶⁸Ga-DOTATATE PET/CT. The two PET/CT studies were interpreted independently and were compared for patient-level and segment-level concordance, as well as for the degree of radiotracer uptake. Follow-up ⁶⁸Ga-DOTATATE PET/CT was performed in eight patients.

Patient-level concordance was 91%: ten patients had multifocal DOTATATE uptake (active cardiac sarcoidosis) and one patient showed diffuse DOTATATE uptake. Segment-level agreement was 77.1% (Kappa 0.53 ± 0.07). The SUVmax-to-blood pool ratio was lower on ⁶⁸Ga-DOTATATE PET/CT (3.2 ± 0.6 vs. 4.9 ± 1.5, P = 0.006 on paired t test). Follow-up ⁶⁸Ga-DOTATATE PET/CT showed one case of complete response and one case of partial response, while ¹⁸F-FDG PET/CT showed four cases of response, including three with complete response.

Compared to ¹⁸F-FDG PET/CT, ⁶⁸Ga-DOTATATE PET/CT can identify active cardiac sarcoidosis with high patient-level concordance, but with moderate segment-level concordance, low signal-to-background ratio, and underestimation of treatment response.