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Pheochromocytoma and Extraadrenal Abdominal Paraganglioma


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Pheochromocytoma and Extraadrenal Abdominal Paraganglioma

Henri J.L.M. Timmers1,2, Mohiuddin Hadi3, Jorge A. Carrasquillo3, Clara C. Chen3, Lucia Martiniova1, Millie Whatley3, Alexander Ling4, Graeme Eisenhofer5, Karen T. Adams1 and Karel Pacak1

 

1 Reproductive Biology and Medicine Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; 2 Department of Endocrinology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; 3 Nuclear Medicine Department, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland; 4 Department of Diagnostic Radiology, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland; and 5 Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland

 

Correspondence: For correspondence or reprints contact: Karel Pacak, MD, PhD, DSc, Reproductive Biology and Medicine Branch, National Institute of Child Health and Human Development, 10 Center Dr., Bldg. 10, CRC, RM 1-E 3140, MSC 1109, Bethesda, MD 20892-1109. E-mail: karel@mail.nih.gov 6-18

 

F-fluoro-L-3,4-dihydroxyphenylalanine (18F-DOPA) PET isa useful tool for the detection of certain neuroendocrine tumors,especially with the preadministration of carbidopa, an inhibitorof DOPA decarboxylase. Whether carbidopa also improves 18F-DOPAPET of adrenal pheochromocytomas and extraadrenal paragangliomasis unknown. The aim of this study was to investigate the sensitivityof 18F-DOPA PET in the detection of paraganglioma and its metastaticlesions and to evaluate whether tracer uptake by the tumorsis enhanced by carbidopa.

 

Methods: Two patients with nonmetastaticadrenal pheochromocytoma, and 9 patients with extraadrenal abdominalparaganglioma (1 nonmetastatic, 8 metastatic), underwent whole-bodyCT, MRI, baseline 18F-DOPA PET, and 18F-DOPA PET with oral preadministrationof 200 mg of carbidopa. The dynamics of tracer uptake by theselesions and the physiologic distribution of 18F-DOPA in normaltissues were recorded.

Results: Seventy-eight lesions were detectedby CT or MRI, 54 by baseline 18F-DOPA PET (P = 0.0022 vs. CT/MRI),and 57 by 18F-DOPA PET plus carbidopa (P = 0.0075 vs. CT/MRI,not statistically significant vs. baseline). In reference tofindings on CT and MRI, the sensitivities of baseline 18F-DOPAPET were 47.4% for lesions and 55.6% for positive body regions,versus 50.0% (lesions) and 66.7% (regions) for 18F-DOPA PETplus carbidopa (neither is statistically significant vs. baseline).Compared with baseline, carbidopa detected additional lesionsin 3 (27%) of 11 patients. Carbidopa increased the mean (?SD)peak standardized uptake value in index tumor lesions from 6.4? 3.9 to 9.1 ? 5.6 (P = 0.037). Pancreatic physiologic18F-DOPA uptake, which may mask adrenal pheochromocytoma, isblocked by carbidopa.

 

Conclusion: Carbidopa enhances the sensitivityof 18F-DOPA PET for adrenal pheochromocytomas and extraadrenalabdominal paragangliomas by increasing the tumor-to-backgroundratio of tracer uptake. The sensitivity of 18F-DOPA PET formetastases of paraganglioma appears to be limited.

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