PET在神经系统的应用

Applications of PET in the Nervous System

正电子发射计算机断层(PET)是利用发射正电子的短半衰期放射性核素和PET扫描仪进行脏器断层显像的技术。将发射正电子的示踪剂注入血流,随即到达全身,聚集在特定器官或器官的某一区域,利用PET扫描仪显像。临床上最常用的发射正电子的示踪剂是^(18)F标记的氟代脱氧葡萄糖(^(18)F-FDG)。 PET作为一种非创伤性显像技术,其特点是:具有独特的反映活体生化和(或)生理过程的性能;所用放射性药物类似人体内生的生物学化合物;最先进的PET扫描仪有较高的分辨率,全身断层显像可以显示横断、冠状和矢状断面。 本文复习了PET脑显像在临床和研究工作中的应用。对于痴呆患者,PET用于不同类型痴呆的鉴别诊断;PET不仅在早期急性脑梗塞的诊断和定位以及评价预后方面起重要作用,而且为脑血管疾病患者的神经生理学和神经病理学机理研究提供了有价值的帮助;癫痫PET显像主要是在手术前识别患者癫痫灶;^(18)F-多巴受体显像能鉴别帕金森氏病和其它帕金森氏神经功能障碍综合征;^(18)F-FDG PET显像测定脑葡萄糖代谢利用程度可提供脑肿瘤重要信息。另外,PET也用于人脑功能的研究。

Positron emission computed tomography(PET) is a tomographic method that uses short - livedpositron emitting radionuclides and a PET scanner. Whena positron emitting tracer is injected into the blood stream,it travels around the body, achieving higher concentrationin particular organs or regions within organs. PET Scanneris able to derive images of regional variations in tracerconcentration. The most frequently used PET tracer tostudy patients is ^(18)F - fluorodeoxyglucose (^(18)F - FDG). As a noninvasively imaging modality, there are sev-eral features of PET as follows: it has unique ability toimage biochemical and/or physiological processes in vivo; the radiopharmaceuticals resemble endogenous com-pounds; the new generation of PET scanners has achieveda reasonable higher resolution; whole body PET can bedisplayed as tomographic images in the transaxial, coro-nal, or sagittal planes. This review article outlines some of the clinical ap-plications and studies of PET applied to brain imag-ing. Functional radionuclide imaging of PET has beenused in the evaluation of dementia. The usefulness ofPET in these patients is gaining differential diagnosis ofdifferent types of dementia. PET May play an importantrole in the diagnosis and location of early acute cerebralinfarctions and the prognostic assessment. PET Studiesmake a valuable contribution to the study of neurophysio-logical and neuropathological mechanisms in patientswith cerebrovascular disease. The main objection of PETimaging in epilepsy is the identification of epileptic focibefore surgery. The use of PET with 18F - dopa appearsto enable discrimination between typical Parkinson's dis-ease and other forms of Parkinsonism. The introduction of^(18)F - FDG to measure the degree of cerebral glucose usehas provided considerable new information about braintumors. Moreover, PET can also be used to study humanbrain function.