Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland, United States of America.
PLoS One. 2011;6(9):e25309. doi: 10.1371/journal.pone.0025309. Epub 2011 Sep 27.
As a reported agonist, ¹¹C-CUMI-101 is believed to selectively bind the G-protein-coupled state of the serotonin-1A (5-HT(1A)) receptor, thereby providing a measure of the active subset of all 5-HT(1A) receptors in brain. Although ¹¹C-CUMI-101 has been successfully used to quantify 5-HT(1A) receptors in human and monkey brain, its radiation exposure has not previously been reported. The purpose of this study was to calculate the radiation exposure to organs of the body based on serial whole-body imaging with positron emission tomography (PET) in human subjects.
Nine healthy volunteers were injected with 428±84 MBq (mean ± SD) (11)C-CUMI-101 and then imaged with a PET-only device for two hours from head to mid-thigh. Eleven source organs (brain, heart, liver, pancreas, stomach, spleen, lungs, kidneys, lumbar spine L1-5, thyroid, and urinary bladder) were identified on whole body images and used to calculate radiation doses using the software program OLINDA/EXM 1.1. To confirm that we had correctly identified the pancreas, a tenth subject was imaged on a PET/CT device.
Brain had high uptake (∼11% of injected activity (IA)) at 10 min. Although liver had the highest uptake (∼35% IA at 120 min), excretion of this activity was not visible in gall bladder or intestine during the scanning session. Organs which received the highest doses (microSv/MBq) were pancreas (32.0), liver (18.4), and spleen (14.5). The effective dose of ¹¹C-CUMI-101 was 5.3±0.5 microSv/MBq.
The peak brain uptake (∼11% IA) of ¹¹C-CUMI-101 is the highest among more than twenty ¹¹C-labeled ligands reported in the literature and provides good counting statistics from relatively low injected activities. Similar to that of other ¹¹C-labeled ligands for brain imaging, the effective dose of ¹¹C-CUMI-101 is 5.3±0.5 microSv/MBq, a value that can now be used to estimate the radiation risks in future research studies.
¹¹C-CUMI-101 作为一种报道的激动剂，据信可选择性地结合血清素-1A（5-HT1A）受体的 G 蛋白偶联状态，从而提供大脑中所有 5-HT1A 受体的活性亚群的测量值。虽然¹¹C-CUMI-101 已成功用于量化人和猴脑中的 5-HT1A 受体，但以前没有报告过其辐射暴露情况。本研究的目的是根据人体的正电子发射断层扫描（PET）全身成像来计算身体器官的辐射暴露。
9 名健康志愿者注射 428±84MBq（平均值±标准差）（11）C-CUMI-101，然后使用仅 PET 设备从头部到大腿中部进行两小时的成像。在全身图像上识别出 11 个源器官（脑、心脏、肝脏、胰腺、胃、脾脏、肺、肾脏、腰椎 L1-5、甲状腺和膀胱），并使用软件程序 OLINDA/EXM 1.1 计算辐射剂量。为了确认我们正确识别了胰腺，对第十名受试者进行了 PET/CT 设备成像。
大脑在 10 分钟时具有高摄取（约 11%的注射量（IA））。尽管肝脏具有最高的摄取（约 120 分钟时为 35%IA），但在扫描过程中胆囊或肠道中未观察到这种活性的排泄。接受最高剂量（微Sv/MBq）的器官是胰腺（32.0）、肝脏（18.4）和脾脏（14.5）。¹¹C-CUMI-101 的有效剂量为 5.3±0.5 微Sv/MBq。
¹¹C-CUMI-101 的脑摄取峰值（约 11%IA）是文献中报道的二十多种¹¹C 标记配体中最高的，从相对较低的注射活性中提供了良好的计数统计数据。与其他用于脑成像的¹¹C 标记配体类似，¹¹C-CUMI-101 的有效剂量为 5.3±0.5 微Sv/MBq，现在可以用来估计未来研究中的辐射风险。
