A Prospective Comparative Study of ¹⁸F-FDOPA PET/CT Versus ¹²³I-MIBG Scintigraphy With SPECT/CT for the Diagnosis of Pheochromocytoma and Paraganglioma

Purpose: This study aimed to compare the diagnostic performances of F-18-FDOPA PET/CT and I-123-MIBG scintigraphy with SPECT/CT for detection of pheochromocytoma and paraganglioma (PPGL).Patients and Methods: We conducted a prospective, single-institution comparative study. Patients suspected of having PPGL or those showing recurrence and/or distant metastasis of PPGL were enrolled. The primary objective was to affirm the noninferiority of F-18-FDOPA PET/CT for diagnostic sensitivity. Both I-123-MIBG scintigraphy with SPECT/CT (at 4 and 24 hours) and F-18-FDOPA PET/CT (at 5 and 60 minutes after radiotracer administration) were performed. The final diagnosis was established either pathologically or via clinical follow-up. Nuclear physicians, unaware of the clinical data, undertook image analysis.Results: Thirty-two patients were evaluated: 14 of 21 with an initial diagnosis and 9 of 11 with recurrence/metastasis had PPGLs in their final diagnoses. In patient-based analyses, F-18-FDOPA PET/CT (95.7%) exhibited noninferior sensitivity compared with I-123-MIBG SPECT/CT (91.3%), within the predetermined noninferiority margin of -12% by a 95% confidence interval lower limit of -10%. Both modalities showed no significant difference in specificity (88.9% vs 88.9%). In the region-based analysis for the recurrence/metastasis group, F-18-FDOPA PET/CT demonstrated significantly higher sensitivity compared with I-123-MIBG SPECT/CT (86.2% vs 65.5%, P = 0.031) and superior interobserver agreement (kappa = 0.94 vs 0.85). The inclusion of an early phase in dual-phase F-18-FDOPA PET/CT slightly improved diagnostic performance, albeit not to a statistically significant degree.Conclusions: F-18-FDOPA PET/CT demonstrated noninferior sensitivity and comparable specificity to I-123-MIBG SPECT/CT in the diagnosing PPGL. Notably, in the assessment of PPGL recurrence and metastasis, F-18-FDOPA PET/CT outperformed I-123-MIBG SPECT/CT in terms of both sensitivity and interobserver agreement.