Inoue T, Shibasaki T, Oriuchi N, Aoyagi K, Tomiyoshi K, Amano S, Mikuni M, Ida I, Aoki J, Endo K
Department of Nuclear Medicine, Gunma University School of Medicine, Maebashi, Japan.
J Nucl Med. 1999 Mar;40(3):399-405.
We have developed 18F-labeled alpha-methyl tyrosine (FMT) for PET imaging. The aim of this study was to evaluate the clinical application potential of FMT for patients with brain tumors.
Eleven healthy volunteers and 20 patients with brain tumors were injected with 185 MBq (5 mCi) FMT. In 3 healthy volunteers, whole-body imaging and urinary and plasma analysis were conducted for the assessment of the biodistribution of FMT. The normal range of cortical standardized uptake value (SUV) as a reference for comparing tumor SUV of FMT was estimated by using PET data obtained at 30 min postinjection in 8 healthy volunteers. Dynamic PET scans were conducted for 100 min in 4 healthy volunteers and for 30 min in 15 patients with brain tumors. The 10-min static images in another 4 volunteers and all patients were obtained at 30 min postinjection. In 13 patients, FMT uptake in the brain tumor was compared with 18F-fluorodeoxyglucose (FDG). Tumor-to-normal cortex count (T/N) ratio and tumor-to-white matter count (T/W) ratio and SUVs of brain tumors were determined on FMT and FDG PET images.
Approximately 1480 MBq (40 mCi) FMT were produced in one radiosynthesis. Percentage injected dose (%ID) of FMT in the brain ranged from 2.8% to 4.9%, and approximately 50%ID of FMT was excreted in urine during 60 min postinjection, of which 86.6% was unmetabolized FMT. A faint physiological brain uptake with SUV of 1.61 +/- 0.32 (mean +/- SD, n = 8) was observed in healthy volunteers. Tumor SUV of FMT ranged from 1.2 to 8.2, with mean value of 2.83 +/- 1.57 (n = 23), which was significantly higher than that of the cortical area in healthy volunteers (P < 0.01). T/N and T/W ratios of FMT were significantly higher than those of FDG (2.53 +/- 1.31 versus 1.32 +/- 1.46, P < 0.001; 3.99 +/- 2.10 versus 1.39 +/- 0.65, P < 0.0001, respectively).
FMT, like other radiolabeled amino acids, can provide high-contrast PET images of brain tumors.
我们已研发出用于正电子发射断层显像（PET）的18F标记的α-甲基酪氨酸（FMT）。本研究的目的是评估FMT在脑肿瘤患者中的临床应用潜力。
11名健康志愿者和20名脑肿瘤患者注射了185 MBq（5 mCi）的FMT。对3名健康志愿者进行全身显像以及尿液和血浆分析，以评估FMT的生物分布。通过使用8名健康志愿者注射后30分钟获得的PET数据，估算皮质标准化摄取值（SUV）的正常范围，作为比较FMT肿瘤SUV的参考。对4名健康志愿者进行100分钟的动态PET扫描，对15名脑肿瘤患者进行30分钟的动态PET扫描。在另外4名志愿者和所有患者注射后30分钟获得10分钟静态图像。在13名患者中，比较脑肿瘤中FMT的摄取与18F-氟脱氧葡萄糖（FDG）的摄取。在FMT和FDG PET图像上确定肿瘤与正常皮质计数（T/N）比、肿瘤与白质计数（T/W）比以及脑肿瘤的SUV。
一次放射性合成可产生约1480 MBq（40 mCi）的FMT。FMT在脑中的注射剂量百分比（%ID）范围为2.8%至4.9%，注射后60分钟内约50%ID的FMT经尿液排出，其中86.6%为未代谢的FMT。在健康志愿者中观察到脑的生理性微弱摄取，SUV为1.61±0.32（平均值±标准差，n = 8）。FMT的肿瘤SUV范围为1.2至8.2，平均值为2.83±1.57（n = 23），显著高于健康志愿者皮质区域的SUV（P < 0.01）。FMT的T/N和T/W比显著高于FDG的T/N和T/W比（分别为2.53±1.31对1.32±1.46，P < 0.001；3.99±2.10对1.39±0.65，P < 0.0001）。
与其他放射性标记氨基酸一样，FMT能够提供脑肿瘤的高对比度PET图像。
