Differential uptake of O-(2-18F-fluoroethyl)-L-tyrosine, L-3H-methionine, and 3H-deoxyglucose in brain abscesses
Differential uptake of O-(2-18F-fluoroethyl)-L-tyrosine, L-3H-methionine, and 3H-deoxyglucose in brain abscesses
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DOI：
10.2967/jnumed.107.046615
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发表时间：
2007-12-01
影响因子：
9.3
通讯作者：
Langen, Karl-Josef
中科院分区：
文献类型：
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作者：
Salber, Daumar;Stoffels, Gabriele;Langen, Karl-Josef
氨基酸O-（2-F-18-氟乙基）-L-酪氨酸（F-18-FET）已被证明是脑肿瘤成像的有用示踪剂。实验研究表明，在炎症细胞中没有摄取F-18-FET，但在单个人脑肿瘤病例中报告了摄取增加。为了探索这种不一致性，我们研究了F-18-FET与L-[甲基-H-3]甲硫氨酸（H-3-MET）和D-H-3-脱氧葡萄糖（（3）HDG）在大鼠脑和小牛胸腺中的摄取。方法：采用金黄色葡萄球菌（Staphylococcus aureus）接种于FisherCDF大鼠的脑（n = 9）和小腿（n = 5），建立脓疡模型。5天后静脉注射F-18-FET和H-3-MET（n = 10）或F-18-FET和H-3-DG（n = 4）。注射后1小时处死大鼠，并使用双示踪剂放射自显影术研究脑或小腿肌肉。计算病灶与背景比值（L/B）和标准化摄取值（SUV）。放射自显影与组织学和免疫染色胶质纤维酸性蛋白（GFAP），CD 68的巨噬细胞，和CD 11b的小胶质细胞进行了比较。结果：F-18-FET在巨噬细胞浸润区域和脑水肿边缘的活化小胶质细胞中的摄取较低（L/B，1.5 ± 0.4）。相比之下，观察到H-3-MET以及H-3-DG的高摄取（L/B，H-3-MET为4.1 +/- 1.1对比H-3-DG为3.1 +/- 1.5; P < 0.01对比F-18-FET）。小牛流产的结果相似。在脑水肿附近，观察到F-18-FET（L/B，1.8 +/- 0.3）和H-3-MET（L/B，1.8 +/- 0.4）的摄取略微增加，而H-3-DG分布正常（L/B，1.2 +/- 0.2）。抗GFAP免疫荧光显示这些区域弥漫性星形细胞增多。结论：实验结果表明，F-18-FET在实验性脑水肿的巨噬细胞和活化的小胶质细胞中无蓄积，而H-3-MET和H-3-DG在这些细胞中有高摄取。因此，F-18-FET对胶质瘤的特异性可能上级H-3-MET和H-3-DG。在人脑肿瘤中增加的F-18-FET摄取似乎与反应性星形细胞增多有关。
The amino acid O-(2-F-18-fluoroethyl)-L-tyrosine (F-18-FET) has been shown to be a useful tracer for brain tumor imaging. Experimental studies demonstrated no uptake of F-18-FET in inflammatory cells but increased uptake has been reported in single cases of human brain abscesses. To explore this inconsistency, we investigated the uptake of F-18-FET in comparison with that of L-[methyl-H-3]methionine (H-3-MET) and D-H-3-deoxyglucose ((3)HDG) in brain and calf abscesses in rats. Methods: Abscesses were induced in the brain (n = 9) and calf (n = 5) of Fisher CDF rats after inoculation of Staphylococcus aureus. Five days later, F-18-FET and H-3-MET (n = 10) or F-18-FET and H-3-DG (n = 4) were injected intravenously. One hour after injection the rats were sacrificed, and the brain or calf muscle was investigated using dual-tracer autoradiography. Lesion-to-background ratios (L/B) and standardized uptake values (SUVs) were calculated. The autoradiograms were compared with histology and immunostaining for glial fibriilary acidic protein (GFAP), CD68 for macrophages, and CD11b for microglia. Results: F-18-FET uptake in the area of macrophage infiltration and activated microglia at the rim of the brain abscesses was low (L/B, 1.5 +/- 0.4). In contrast, high uptake was observed for H-3-MET as well as for H-3-DG (L/B, 4.1 +/- 1.1 for H-3-MET vs. 3.1 +/- 1.5 for H-3-DG; P < 0.01 vs. F-18-FET). Results for calf abscesses were similar. In the vicinity of the brain abscesses, slightly increased uptake was noted for F-18-FET (L/B, 1.8 +/- 0.3) and H-3-MET (L/B, 1.8 +/- 0.4), whereas H-3-DG distribution was normal (L/B, 1.2 +/- 0.2). Anti-GFAP immunofluorescence showed a diffuse astrocytosis in those areas. Conclusion: Our results demonstrate that there is no accumula tion of F-18-FET in macrophages and activated microglia in experimental brain abscesses, whereas H-3-MET and H-3-DG exhibit high uptake in these cells. Thus, the specificity of F-18-FET for gliomas may be superior to that H-3-MET and H-3-DG. Increased F-18-FET uptake in human brain abscesses appears to be related to reactive astrocytosis.