6-[F-18]Fluoro-l-Dihydroxyphenylalanine Positron Emission Tomography Is Superior to Conventional Imaging with 123I-Metaiodobenzylguanidine Scintigraphy, Computer Tomography, and Magnetic Resonance Imaging in Localizing Tumors Causing Catecholamine Excess

Abstract

Context: Catecholamine excess is rare, but symptoms may be life threatening. Objective: The objective of the study was to investigate the sensitivity of 6-[F-18]fluoro-l-dihydroxyphenylalanine positron emission tomography (¹⁸F-DOPA PET), compared with ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy and computer tomography (CT)/magnetic resonance imaging (MRI) for tumor localization in patients with catecholamine excess. Design and Setting: All consecutive patients with catecholamine excess visiting the University Medical Center Groningen, Groningen, The Netherlands, between March 2003 and January 2008 were eligible. Patients: Forty-eight patients were included. The final diagnosis was pheochromocytoma in 40, adrenal hyperplasia in two, paraganglioma in two, ganglioneuroma in one, and unknown in three. Main Outcome Measures: Sensitivities and discordancy between ¹⁸F-DOPA PET, ¹²³I-MIBG, and CT or MRI were analyzed for individual patients and lesions. Metanephrines and 3-methoxytyramine in plasma and urine and uptake of ¹⁸F-DOPA with PET were measured to determine the whole-body metabolic burden and correlated with biochemical tumor activity. The gold standard was a composite reference standard. Results:¹⁸F-DOPA PET showed lesions in 43 patients, ¹²³I-MIBG in 31, and CT/MRI in 32. Patient-based sensitivity for ¹⁸F-DOPA PET, ¹²³I-MIBG, and CT/MRI was 90, 65, and 67% (P < 0.01 for ¹⁸F-DOPA PET vs. both ¹²³I-MIBG and CT/MRI, P = 1.0 ¹²³I-MIBG vs. CT/MRI). Lesion-based sensitivities were 73, 48, and 44% (P < 0.001 for ¹⁸F-DOPA PET vs. both ¹²³I-MIBG and CT/MRI, P = 0.51 ¹²³I-MIBG vs. CT/MRI). The combination of ¹⁸F-DOPA PET with CT/MRI was superior to ¹²³I-MIBG with CT/MRI (93 vs. 76%, P < 0.001). Whole-body metabolic burden measured with ¹⁸F-DOPA PET correlated with plasma normetanephrine (r = 0.82), urinary normetanephrine (r = 0.84), and metanephrine (r = 0.57). Conclusion: To localize tumors causing catecholamine excess, ¹⁸F-DOPA PET is superior to ¹²³I-MIBG scintigraphy and CT/MRI. 18F-DOPA PET is superior to conventional imaging with 12316 I-MIBG scintigraphy and CT/MRI in localizing tumors causing catecholamine excess.