Department of Pediatrics, School of Medicine, Wayne State University PET Center, Children's Hospital of Michigan, Detroit Medical Center, Detroit, Michigan 48201, USA.
J Nucl Med. 2010 Jan;51(1):139-44. doi: 10.2967/jnumed.109.066472. Epub 2009 Dec 15.
The PET tracer (11)C-(R)-PK11195 (PK) is an antagonist of the peripheral-type benzodiazepine binding site and allows the noninvasive imaging of microglial activation seen in several neurologic disorders affecting the mature and developing brain. The objective of this study was to derive the biodistribution and in vivo radiation dose estimates of PK in children studied for brain inflammatory conditions and in healthy adults.
Twenty-two children (mean age +/- SD, 9.5 +/- 4 y; range, 4-17 y; 10 girls) who underwent dynamic PK PET for conditions involving brain inflammation were studied. Seven healthy adults (age, 27.4 +/- 7.5 y; range, 22-41 y; 3 women) were evaluated using the same protocol. Normal-organ time-activity curves and residence times were derived and absorbed doses then calculated using the OLINDA software. Two other healthy young adults (1 man, 1 woman) also underwent sequential whole-body PET using a PET/CT scanner to obtain corresponding CT images and PK pharmacokinetics.
PK uptake was highest in the gallbladder and urinary bladder, followed by the liver, kidney, bone marrow, salivary gland, and heart wall, with minimal localization in all other organs including normal brain and lungs. PK was excreted through the hepatobiliary and renal systems. The average effective dose equivalent was 11.6 +/- 0.6 microSv/MBq (mean +/- SD) for young children (age, 4-7 y), 7.7 +/- 1.0 microSv/MBq for older children (age, 8-12 y), 5.3 +/- 0.5 muSv/MBq for adolescents (age, 13-17 y), and 4.6 +/- 2.7 microSv/MBq for adults. The gallbladder wall received the highest radiation dose in children younger than 12 y, whereas the urinary bladder wall received the highest dose in older children and adults. For an administered activity of 17 MBq/kg (0.45 mCi/kg), the effective dose equivalent was about 5 mSv or below for all age groups.
At clinically practical administered activities, the radiation dose from (11)C-PK11195 in both children and adults is comparable to that from other clinical PET tracers and diagnostic radiopharmaceuticals in routine clinical use.
本研究旨在获得用于研究脑部炎症性疾病的儿童和健康成年人中 PK 的体内分布和估算体内辐射剂量。
22 名（平均年龄 ± 标准差，9.5 ± 4 岁；范围，4-17 岁；10 名女性）因脑部炎症接受动态 PK PET 检查的儿童患者参与了本研究。采用相同方案评估了 7 名健康成年人（年龄 27.4 ± 7.5 岁；范围，22-41 岁；3 名女性）。利用 OLINDA 软件，得出正常器官时间-活性曲线和滞留时间，然后计算吸收剂量。另外两名健康的年轻成年人（1 名男性，1 名女性）也进行了全身 PET 检查（使用 PET/CT 扫描仪），以获得相应的 CT 图像和 PK 药代动力学。
PK 的摄取率最高的部位是胆囊和膀胱，其次是肝脏、肾脏、骨髓、唾液腺和心脏壁，所有其他器官（包括正常脑和肺）的摄取率均较低。PK 通过肝胆和肾脏系统排泄。对于年龄在 4-7 岁的幼儿，平均有效当量剂量为 11.6 ± 0.6 μSv/MBq（平均值 ± 标准差）；对于年龄在 8-12 岁的较大儿童，为 7.7 ± 1.0 μSv/MBq；对于年龄在 13-17 岁的青少年，为 5.3 ± 0.5 μSv/MBq；对于成年人，为 4.6 ± 2.7 μSv/MBq。在年龄小于 12 岁的儿童中，胆囊壁接收到的辐射剂量最高，而在年龄较大的儿童和成人中，膀胱壁接收到的辐射剂量最高。对于给予的 17 MBq/kg（0.45 mCi/kg）的活性，所有年龄组的有效当量剂量均约为 5 mSv 或以下。
在临床实际给予的活性下，儿童和成人中（11）C-PK11195 的辐射剂量与常规临床使用的其他临床 PET 示踪剂和放射性诊断药物相当。
