Sporadic Primary Pheochromocytoma: A Prospective Intraindividual Comparison of Six Imaging Tests (CT, MRI, and PET/CT...

BACKGROUND. Recent professional society guidelines for radionuclide imaging of sporadic pheochromocytoma (PHEO) recommend ¹⁸F-fluorodihydroxyphenylala-nine (¹⁸F-FDOPA) as the radiotracer of choice, deeming ⁶⁸Ga-DOTATATE and FDG to be second- and third-line agents, respectively. An additional agent, ¹⁸F-fluorodopamine (¹⁸F-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 ⁶⁸Ga-DOTATATE PET/CT, FDG PET/CT, ¹⁸F-FDOPA PET/CT, ¹⁸F-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 ⁶⁸Ga-DOTATATE PET/CT, FDG PET/CT, ¹⁸F-FDOPA PET/CT, ¹⁸F-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 SUV_max was computed using both readers' measurements. Interreader agreement was assessed using intraclass correlation coefficients (ICCs) for SUV_max. 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 ⁶⁸Ga-DOTATATE PET/CT and FDG PET/CT were completed in all 14 patients, ¹⁸F-FDOPA PET/CT in 11, ¹⁸F-FDA PET/CT in 7, CT in 12, and MRI in 12. Mean conspicuity score for PHEO was 5.0 ± 0.0 for ¹⁸F-FDOPA PET/CT, 4.7 ± 0.5 for MRI, 4.6 ± 0.8 for ¹⁸F-FDA PET/CT, 4.4 ± 1.0 for ⁶⁸Ga-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 ¹⁸F-FDOPA PET/CT, 100.0% (12/12) for MRI, 85.7% (6/7) for ¹⁸F-FDA PET/CT, 78.6% (11/14) for FDG PET/CT, 78.6% (11/14) for ⁶⁸Ga-DOTATATE PET/CT, and 66.7% (8/12) for CT. Lesion-to-liver SUV_max was 10.5 for ¹⁸F-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 SUV_max measurements. CONCLUSION. Findings from this small intraindividual comparative study support ¹⁸F-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. TRIAL REGISTRATION. ClinicalTrials.gov NCT00004847.