Timmers Henri J L M, Hadi Mohiuddin, Carrasquillo Jorge A, Chen Clara C, Martiniova Lucia, Whatley Millie, Ling Alexander, Eisenhofer Graeme, Adams Karen T, Pacak Karel
Reproductive Biology and Medicine Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1109, USA.
J Nucl Med. 2007 Oct;48(10):1599-606. doi: 10.2967/jnumed.107.042721. Epub 2007 Sep 14.
6-(18)F-fluoro-l-3,4-dihydroxyphenylalanine ((18)F-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 (18)F-DOPA PET of adrenal pheochromocytomas and extraadrenal paragangliomas is unknown. The aim of this study was to investigate the sensitivity of (18)F-DOPA PET in the detection of paraganglioma and its metastatic lesions and to evaluate whether tracer uptake by the tumors is enhanced by carbidopa.
Two patients with nonmetastatic adrenal pheochromocytoma, and 9 patients with extraadrenal abdominal paraganglioma (1 nonmetastatic, 8 metastatic), underwent whole-body CT, MRI, baseline (18)F-DOPA PET, and (18)F-DOPA PET with oral preadministration of 200 mg of carbidopa. The dynamics of tracer uptake by these lesions and the physiologic distribution of (18)F-DOPA in normal tissues were recorded.
Seventy-eight lesions were detected by CT or MRI, 54 by baseline (18)F-DOPA PET (P = 0.0022 vs. CT/MRI), and 57 by (18)F-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 (18)F-DOPA PET were 47.4% for lesions and 55.6% for positive body regions, versus 50.0% (lesions) and 66.7% (regions) for (18)F-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 (18)F-DOPA uptake, which may mask adrenal pheochromocytoma, is blocked by carbidopa.
Carbidopa enhances the sensitivity of (18)F-DOPA PET for adrenal pheochromocytomas and extraadrenal abdominal paragangliomas by increasing the tumor-to-background ratio of tracer uptake. The sensitivity of (18)F-DOPA PET for metastases of paraganglioma appears to be limited.
6-(18)F-氟-L-3,4-二羟基苯丙氨酸（(18)F-DOPA）PET是检测某些神经内分泌肿瘤的有用工具，尤其是在预先给予多巴脱羧酶抑制剂卡比多巴的情况下。卡比多巴是否也能改善肾上腺嗜铬细胞瘤和肾上腺外副神经节瘤的(18)F-DOPA PET检查尚不清楚。本研究的目的是调查(18)F-DOPA PET在检测副神经节瘤及其转移灶方面的敏感性，并评估卡比多巴是否能增强肿瘤对示踪剂的摄取。
2例非转移性肾上腺嗜铬细胞瘤患者和9例肾上腺外腹部副神经节瘤患者（1例非转移性，8例转移性）接受了全身CT、MRI、基线(18)F-DOPA PET检查，以及口服200 mg卡比多巴后的(18)F-DOPA PET检查。记录这些病变对示踪剂摄取的动态变化以及(18)F-DOPA在正常组织中的生理分布。
CT或MRI检测到78个病灶，基线(18)F-DOPA PET检测到54个（与CT/MRI相比，P = 0.0022），(18)F-DOPA PET加卡比多巴检测到57个（与CT/MRI相比，P = 0.0075，与基线相比无统计学意义）。参照CT和MRI的检查结果，基线(18)F-DOPA PET对病灶的敏感性为47.4%，对阳性身体区域的敏感性为55.6%，而(18)F-DOPA PET加卡比多巴对病灶的敏感性为50.0%（病灶），对区域的敏感性为66.7%（区域）（与基线相比均无统计学意义）。与基线相比，卡比多巴在11例患者中的3例（27%）检测到了额外的病灶。卡比多巴使指数肿瘤病灶的平均（±标准差）峰值标准化摄取值从6.4±3.9提高到9.1±5.6（P = 0.037）。可能掩盖肾上腺嗜铬细胞瘤的胰腺生理性(18)F-DOPA摄取被卡比多巴阻断。
卡比多巴通过提高示踪剂摄取的肿瘤与背景比值，增强了(18)F-DOPA PET对肾上腺嗜铬细胞瘤和肾上腺外腹部副神经节瘤的敏感性。(18)F-DOPA PET对副神经节瘤转移灶似乎敏感性有限。
