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-DOPAPET), 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, andunknownin 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 plasmaandurineanduptake of 18F-DOPAwith PETweremeasuredto 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. Copyright © 2009 by The Endocrine Society.