Division of Nuclear Medicine, KU Leuven and University Hospital Gasthuisberg, Herestraat 49 bus 7003, 3000, Leuven, Belgium.
Eur J Nucl Med Mol Imaging. 2010 Jun;37(6):1164-73. doi: 10.1007/s00259-010-1383-7. Epub 2010 Feb 25.
Small animal PET can be applied to study molecular processes in animal models of a variety of human diseases. In order to keep the animals in a restricted position during imaging, anaesthesia is in many instances inevitable. Using small animal PET and ex vivo autoradiography, we examined the influence of pentobarbital and isoflurane anaesthesia on the rat brain uptake of [(18)F]MK-9470, a radioligand for the type 1 cannabinoid receptor.
PET imaging was performed on adult Wistar rats under pentobarbital (n = 6) and isoflurane anaesthesia (n = 7), and under control conditions (free moving during tracer uptake, n = 8). Parametric PET images were generated, anatomically standardized and analysed by voxel-based Statistical Parametric Mapping and a predefined volume of interest approach. Immediately after in vivo PET, brains were processed for ex vivo autoradiography using manually placed regions of interest. An extra group (n = 6) was included ex vivo, in which animals were intravenously injected without the use of anaesthetics.
Using in vivo and ex vivo molecular imaging techniques, no significant changes in absolute [(18)F]MK-9470 uptake were present in the brain of pentobarbital and isoflurane rats as compared to control conditions. Relative [(18)F]MK-9470 uptake PET values obtained applying global scaling were, however, decreased in the cortex under both anaesthetics (pentobarbital: -13.3+/-1.4%; isoflurane -8.7 +/- 3.1%), while an increase was seen in the cerebellum by 13.5 +/- 4.0% and 13.9 +/- 4.1% under pentobarbital and isoflurane, respectively. Ex vivo results were in agreement with in vivo findings.
These findings suggest a similar, regionally specific interference of pentobarbital and isoflurane anaesthesia with in vivo CB1 receptor imaging using [(18)F]MK-9470.
小动物 PET 可应用于研究各种人类疾病的动物模型中的分子过程。为了在成像过程中使动物保持在受限的位置，在许多情况下不可避免地需要使用麻醉。我们使用小动物 PET 和离体放射自显影技术，研究了戊巴比妥和异氟烷麻醉对放射性配体 [(18)F]MK-9470 在大鼠脑中摄取的影响，该放射性配体用于 1 型大麻素受体。
在戊巴比妥（n = 6）和异氟烷麻醉（n = 7）下以及在对照条件下（在示踪剂摄取期间自由移动，n = 8）对成年 Wistar 大鼠进行 PET 成像。生成参数化 PET 图像，通过基于体素的统计参数映射和预定义的感兴趣区方法进行解剖标准化和分析。在体内 PET 后，立即使用手动放置的感兴趣区对大脑进行离体放射自显影处理。还包括一个额外的组（n = 6），其中动物在没有使用麻醉剂的情况下静脉注射。
使用体内和离体分子成像技术，与对照条件相比，戊巴比妥和异氟烷大鼠脑内的绝对 [(18)F]MK-9470 摄取没有明显变化。然而，应用全局缩放获得的相对 [(18)F]MK-9470 摄取 PET 值在两种麻醉剂下皮质均降低（戊巴比妥：-13.3+/-1.4%；异氟烷-8.7 +/- 3.1%），而在小脑则分别增加 13.5 +/- 4.0%和 13.9 +/- 4.1%。离体结果与体内结果一致。
这些发现表明戊巴比妥和异氟烷麻醉对使用 [(18)F]MK-9470 进行体内 CB1 受体成像具有相似的、区域性特定的干扰。
