Prospective comparison of (68)Ga-DOTATATE and (18)F-FDOPA PET/CT in patients with various pheochromocytomas and paragangliomas with emphasis on sporadic cases

Purpose: Pheochromocytomas/paragangliomas (PHEOs/PGLs) overexpress somatostatin receptors and recent studies have already shown excellent results in the localization of these tumors using (68)Ga-labeled somatostatin analogs ((68)Ga-DOTA-SSA), especially in patients with germline succinate dehydrogenase subunit B gene (SDHB) mutations and head and neck PGLs (HNPGLs). The value of (68)Ga-DOTA-SSA has to be established in sporadic cases, including PHEOs. Thus, the aim of this study was to compare (68)Ga-DOTATATE PET/CT, (18)F-FDOPA PET/CT, and conventional imaging in patients with various PHEOs/PGLs with a special emphasis on sporadic cases, including those located in the adrenal gland.

Design: (68)Ga-DOTATATE, (18)F-FDOPA PET/CT, and conventional imaging (contrast-enhanced CT and MRI with MR angiography sequences) were prospectively performed in 30 patients (8 with SDHD mutations, 1 with a MAX mutation and 21 sporadic cases) with PHEO/PGL at initial diagnosis or relapse.

Results: The patient-based sensitivities were 93 % (28/30), 97 % (29/30), and 93 % (28/30) for (68)Ga-DOTATATE PET/CT, (18)F-FDOPA PET/CT, and conventional imaging, respectively. The lesion-based sensitivities were 93 % (43/46), 89 % (41/46), and 76 % (35/46) for (68)Ga-DOTATATE PET/CT, (18)F-FDOPA PET/CT, and conventional imaging respectively (p = 0.042). (68)Ga-DOTATATE PET/CT detected a higher number of HNPGLs (30/30) than (18)F-FDOPA PET/CT (26/30; p = 0.112) and conventional imaging (24/30; p = 0.024). (68)Ga-DOTATATE PET/CT missed two PHEOs of a few millimeters in size and a large recurrent PHEO. One lesion was considered false-positive on (68)Ga-DOTATATE PET/CT and corresponded to a typical focal lesion of fibrous dysplasia on MRI. Among the 11 lesions missed by conventional imaging, 7 were detected by conventional imaging with knowledge of the PET results (4 HNPGLs, 2 LNs, and 1 recurrent PHEO).

Conclusion: (68)Ga-DOTATATE PET/CT is the most sensitive tool in the detection of HNPGLs, especially SDHD-related tumors, which may be very small and fail to concentrate sufficient (18)F-FDOPA. The present study further expands the use of (68)Ga-DOTATATE for all patients with HNPGLs, regardless of their genotype. (68)Ga-DOTATATE PET/CT may be inferior to (18)F-FDOPA PET/CT in the detection PHEOs.