The Effects of Carbidopa on Uptake of 6-18F-Fluoro-l-DOPA in PET of Pheochromocytoma and Extraadrenal Abdominal Paraganglioma

Journal of Nuclear Medicine

Henri J.L.M. Timmers¹  Lucia Martiniova¹  Clara C. Chen¹  Jorge A. Carrasquillo¹  Alexander Ling¹  Karen T. Adams¹  Graeme Eisenhofer¹  Karel Pacak¹  Millie Whatley¹  Mohiuddin Hadi¹ 

关键词: 6-fluoro-DOPA;    6-¹⁸F-fluorodopamine;    carbidopa;    pheochromocytoma;    paraganglioma;    positron emission tomography;    standardized uptake value;    region of interest;   

DOI  :  10.2967/jnumed.107.042721

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

6-18F-fluoro-l-3,4-dihydroxyphenylalanine (18F-DOPA) PET is a useful tool for the detection of certain neuroendocrine tumors, especially with the preadministration of carbidopa, an inhibitor of DOPA decarboxylase. Whether carbidopa also improves 18F-DOPA PET of adrenal pheochromocytomas and extraadrenal paragangliomas is unknown. The aim of this study was to investigate the sensitivity of 18F-DOPA PET in the detection of paraganglioma and its metastatic lesions and to evaluate whether tracer uptake by the tumors is enhanced by carbidopa. Methods: Two patients with nonmetastatic adrenal pheochromocytoma, and 9 patients with extraadrenal abdominal paraganglioma (1 nonmetastatic, 8 metastatic), underwent whole-body CT, MRI, baseline 18F-DOPA PET, and 18F-DOPA PET with oral preadministration of 200 mg of carbidopa. The dynamics of tracer uptake by these lesions and the physiologic distribution of 18F-DOPA in normal tissues were recorded. Results: Seventy-eight lesions were detected by 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 to findings on CT and MRI, the sensitivities of baseline 18F-DOPA PET were 47.4% for lesions and 55.6% for positive body regions, versus 50.0% (lesions) and 66.7% (regions) for 18F-DOPA PET plus carbidopa (neither is statistically significant vs. baseline). Compared with baseline, carbidopa detected additional lesions in 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 physiologic 18F-DOPA uptake, which may mask adrenal pheochromocytoma, is blocked by carbidopa. Conclusion: Carbidopa enhances the sensitivity of 18F-DOPA PET for adrenal pheochromocytomas and extraadrenal abdominal paragangliomas by increasing the tumor-to-background ratio of tracer uptake. The sensitivity of 18F-DOPA PET for metastases of paraganglioma appears to be limited.

【 授权许可】

Unknown