Sporadic Primary Pheochromocytoma: A Prospective Intraindividual Comparison of Six Imaging Tests (CT, MRI, and PET/CT Using Ga-68-DOTATATE, FDG, F-18-FDOPA, and F-18-FDA)

BACKGROUND. Recent professional society guidelines for radionuclide imaging of sporadic pheochromocytoma (PHEO) recommend F-18-fluorodihydroxyphenylala-nine (F-18-FDOPA) as the radiotracer of choice, deeming Ga-68-DOTATATE and FDG to be second- and third-line agents, respectively. An additional agent, F-18-fluorodopamine (F-18-FDA), remains experimental for PHEO detection. A paucity of research has performed head-to-head comparison among these agents. OBJECTIVE. The purpose of this study was to perform an intraindividual comparison of Ga-68-DOTATATE PET/CT, FDG PET/CT, F-18-FDOPA PET/CT, F-18-FDA PET/CT, CT, and MRI in visualization of sporadic primary PHEO. METHODS. This prospective study enrolled patients referred with clinical suspicion for sporadic PHEO. Patients were scheduled for Ga-68-DOTATATE PET/CT, FDG PET/CT, F-18-FDOPA PET/CT, F-18-FDA PET/CT, whole-body staging CT (portal venous phase), and MRI within a 3-month period. PET/CT examinations were reviewed by two nuclear medicine physicians, and CT and MRI were reviewed by two radiologists; differences were resolved by consensus. Readers scored lesions in terms of confidence in diagnosis of PHEO (1-5 scale; 4-5 considered positive for PHEO). Lesion-to-liver SUVmax was computed using both readers' measurements. Interreader agreement was assessed using intraclass correlation coefficients (ICCs) for SUVmax. Analysis included only patients with histologically confirmed PHEO on resection. RESULTS. The analysis included 14 patients (eight women, six men; mean age, 52.4 +/- 16.8 [SD] years) with PHEO. Both Ga-68-DOTATATE PET/CT and FDG PET/CT were completed in all 14 patients, F-18-FDOPA PET/CT in 11, F-18-FDA PET/CT in 7, CT in 12, and MRI in 12. Mean conspicuity score for PHEO was 5.0 +/- 0.0 for F-18-FDOPA PET/CT, 4.7 +/- 0.5 for MRI, 4.6 +/- 0.8 for F-18-FDA PET/CT, 4.4 +/- 1.0 for Ga-68-DOTATATE PET/CT, 4.3 +/- 1.0 for CT, and 4.1 +/- 1.5 for FDG PET/CT. The positivity rate for PHEO was 100.0% (11/11) for F-18-FDOPA PET/CT, 100.0% (12/12) for MRI, 85.7% (6/7) for F-18-FDA PET/CT, 78.6% (11/14) for FDG PET/CT, 78.6% (11/14) for Ga-68-DOTATATE PET/CT, and 66.7% (8/12) for CT. Lesion-to-liver SUVmax was 10.5 for F-18-FDOPA versus 3.0-4.2 for the other tracers. Interreader agreement across modalities ranged from 85.7% to 100.0% for lesion positivity with ICCs of 0.55-1.00 for SUVmax measurements. CONCLUSION. Findings from this small intraindividual comparative study support F-18-FDOPA PET/CT as a preferred first-line imaging modality in evaluation of sporadic PHEO. CLINICAL IMPACT. This study provides data supporting current guidelines for imaging evaluation of suspected PHEO.