Molecular Imaging Centre (CRC-CIM), Barcelona Biomedical Research Park, Barcelona, Spain.
Mol Imaging Biol. 2011 Aug;13(4):776-84. doi: 10.1007/s11307-010-0398-6.
(11)C-GSK931145 is a novel radioligand suitable for imaging the glycine transporter 1 (GlyT-1) in brain. In the present study, human dosimetry is estimated from baboon and human biodistribution data.
Three baboons and eight healthy human volunteers underwent whole-body positron emission tomography (PET) scans. Human dosimetry was estimated using three different region-of-interest (ROI) delineation methods that ranged in their complexity and execution time: ROIs drawn on anterior-posterior compressed PET images, on subsamples of the organs, and covering the whole-organ. Residence times for each organ were calculated as the area under the time-activity curves divided by the injected activity. Radiation dose estimates were calculated from organ residence times using the OLINDA/EXM software package.
The overall distribution of activity was similar in baboons and humans. Early scans presented high activity in the liver, and moderate activity in the lungs and kidneys. The principal route of clearance was intestinal and no urinary excretion was observed. The limiting organ with the highest radiation-absorbed dose was the liver. The mean effective dose in humans was 4.02 μSv/MBq (male phantom) and 4.95 μSv/MBq (female phantom) (ROIs drawn on subsamples of the organs). The human effective dose estimated from baboon data was ~15% larger than the effective dose estimated from human data.
Human PET imaging of the glycine transporter-1 with (11)C-GSK931145 results in a moderate effective human radiation dose, which allows for multiple PET examinations in the same individual. Among the three methods compared to delineate ROIs, the organ subsampling method shows the best balance between quantitative accuracy and practical application.
(11)C-GSK931145 是一种新型放射性配体，适用于脑内甘氨酸转运体 1（GlyT-1）的成像。本研究从狒狒和人体生物分布数据估算人体剂量。
三只狒狒和八名健康志愿者接受全身正电子发射断层扫描（PET）扫描。使用三种不同的感兴趣区（ROI）勾画方法来估算人体剂量，这些方法在复杂性和执行时间上有所不同：在前-后压缩 PET 图像上勾画 ROI，在器官的子样本上勾画 ROI，以及在整个器官上勾画 ROI。每个器官的停留时间通过时间-活性曲线下面积除以注射活性来计算。使用 OLINDA/EXM 软件包从器官停留时间计算辐射剂量估计。
放射性示踪剂在狒狒和人类中的总体分布相似。早期扫描中，肝脏显示出高活性，肺部和肾脏显示出中等活性。清除的主要途径是肠道，没有观察到尿液排泄。具有最高辐射吸收剂量的限制器官是肝脏。人体的平均有效剂量为 4.02 μSv/MBq（男性体模）和 4.95 μSv/MBq（女性体模）（在器官子样本上勾画 ROI）。从狒狒数据估计的人体有效剂量比从人体数据估计的有效剂量大约 15%。
用（11)C-GSK931145 进行的甘氨酸转运体-1 的人体 PET 成像导致适度的人体辐射剂量，允许在同一个体中进行多次 PET 检查。在所比较的三种勾画 ROI 的方法中，器官子样本方法在定量准确性和实际应用之间表现出最佳的平衡。
