Yamaguchi Aiko, Hanaoka Hirofumi, Fujisawa Yutaka, Zhao Songji, Suzue Kazutomo, Morita Akihiro, Tominaga Hideyuki, Higuchi Tetsuya, Hisaeda Hajime, Tsushima Yoshito, Kuge Yuji, Iida Yasuhiko
Department of Bioimaging Information Analysis, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Japan.
Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-Cho, Suzuka, Mie 510-8760 Japan.
EJNMMI Res. 2015 Apr 30;5:29. doi: 10.1186/s13550-015-0109-z. eCollection 2015.
Previous clinical studies have revealed the potential of [(18)F]-fluoro-L-α-methyltyrosine ((18)F-FAMT) for the differential diagnosis of malignant tumours from sarcoidosis. However, one concern regarding the differential diagnosis with (18)F-FAMT is the possibility of false negatives given the small absolute uptake of (18)F-FAMT that has been observed in some malignant tumours. The aim of this study was to evaluate a usefulness of dynamic (18)F-FAMT positron emission tomography (PET) for differentiating malignant tumours from granulomas.
Rats bearing both granulomas (Mycobacterium bovis bacillus Calmette-Guérin (BCG)-induced) and tumours (C6 glioma cell-induced) underwent dynamic 2-deoxy-2-[(18)F]-fluoro-D-glucose ((18)F-FDG) PET and (18)F-FAMT PET for 120 min on consecutive days. Time-activity curves, static images, mean standardized uptake values (SUVs) and the SUV ratios (SUVRs; calculated by dividing SUV at each time point by that of 2 min after injection) were assessed.
In tumours, (18)F-FAMT showed a shoulder peak immediately after the initial distribution followed by gradual clearance compared with granulomas. Although the mean SUV in the tumours (1.00 ± 0.10) was significantly higher than that in the granulomas (0.88 ± 0.12), a large overlap was observed. In contrast, the SUVR was markedly higher in tumours than in granulomas (50 min/2 min, 0.72 ± 0.06 and 0.56 ± 0.05, respectively) with no overlap. The dynamic patterns, SUVR, and mean SUV of (18)F-FDG in the granulomas were comparable to those in the tumours.
Dynamic (18)F-FAMT and SUVR analysis might compensate for the current limitations and help in improving the diagnostic accuracy of (18)F-FAMT.
先前的临床研究已经揭示了[(18)F]-氟-L-α-甲基酪氨酸((18)F-FAMT)在鉴别恶性肿瘤和结节病方面的潜力。然而，关于使用(18)F-FAMT进行鉴别诊断的一个担忧是，鉴于在一些恶性肿瘤中观察到的(18)F-FAMT绝对摄取量较小，可能会出现假阴性。本研究的目的是评估动态(18)F-FAMT正电子发射断层扫描(PET)在鉴别恶性肿瘤和肉芽肿方面的实用性。
同时患有肉芽肿(卡介苗(BCG)诱导)和肿瘤(C6胶质瘤细胞诱导)的大鼠连续两天接受动态2-脱氧-2-[(18)F]-氟-D-葡萄糖((18)F-FDG)PET和(18)F-FAMT PET检查120分钟。评估时间-活性曲线、静态图像、平均标准化摄取值(SUV)和SUV比值(SUVR；通过将每个时间点的SUV除以注射后2分钟的SUV来计算)。
在肿瘤中，与肉芽肿相比，(18)F-FAMT在初始分布后立即显示出一个肩峰，随后逐渐清除。虽然肿瘤中的平均SUV(1.00±0.10)显著高于肉芽肿中的平均SUV(0.88±0.12)，但观察到有很大重叠。相比之下，肿瘤中的SUVR明显高于肉芽肿(50分钟/2分钟时，分别为0.72±0.06和0.56±0.05)，且无重叠。肉芽肿中(18)F-FDG的动态模式、SUVR和平均SUV与肿瘤中的相当。
动态(18)F-FAMT和SUVR分析可能弥补当前的局限性，并有助于提高(18)F-FAMT的诊断准确性。
