脑代谢-脑血流同期显像在缺血性脑血管病的影像特征与类型

目的研究正电子发射计算机断层(positron emission tomography,PET)脑代谢与脑血流同期显像在缺血性脑血管病(ischemic cerebral vascular disease,ICVD)的影像特征以及匹配关系的类型。方法受检者分为两组,正常人10例,ICVD组87例。采用1日法,首先进行13N-氨水(13N-Ammonia)显像,然后进行氟代脱氧葡萄糖(fludeoxyglucose F-18,18F-FDG)显像。获得脑血流灌注和脑葡萄糖代谢断层影像,并得到各脑区/小脑代谢和血流的放射性计数比值,进一步得到ICVD组的代谢、血流减低百分率和代谢/血流比值。结果 10例正常人脑代谢和脑血流影像表现为放射性分布呈左、右完全性对称和前、后基本对称。代谢与血流影像的放射性摄取程度呈完全匹配型影像。87例ICVD患者发现病灶267个;其中234个病灶表现为18F-FDG摄取减低;189个病灶表现为13N-Ammonia摄取减低;2个病灶表现为13N-Ammonia摄取增高;ICVD病灶大多呈多灶性、不对称性分布。异常影像类型分为5种:Ⅰ型(112个病灶):脑代谢-脑血流匹配性减少,减低程度基本相同;Ⅱ型(76个病灶):脑代谢不同程度减低,脑血流保持正常;Ⅲ型(33个病灶):脑血流不同程度减低,脑代谢保持正常;Ⅳ型:(44个病灶)脑代谢中重度减低,脑血流轻度减低;Ⅴ型:(2个病灶)脑代谢不同程度减低,脑血流增高。第Ⅱ型-第Ⅳ型为代谢-血流不匹配型;第Ⅴ型为代谢-血流反向分布。结论18F-FDG和13N-Ammonia同期PET显像的影像特征与类型,对于研究ICVD脑代谢与脑血流的匹配关系具有重要意义。

Characteristics and patterns of brain positron emission tomographic images in ischemic cerebrovascular disease using 18F-fluorodeoxyglucose and 13N-ammonia

Objective To investigate the characteristics and patterns of brain positron emission tomography (PET) images in ischemic cerebral vascular disease (ICVD) using ¹⁸F-fluorodeoxyglucose (FDG) and ¹³N-ammonia. Methods The study included two groups of subjects: 10 normal adults and 87 patients with ICVD. The brain PET scan using ¹³N-ammonia was firstly performed and after that, ¹⁸F-FDG imaging followed. The PET images and radioactive ratios of cerebral lobes (basal ganglia and thalamus) to cerebellum were obtained. Several semiquantitative parameters were used for further analysis and they were: cerebral glucose metabolism (CGM) value, cerebral blood flow (CBF) value, decreased percent of CGM, decreased percent of CBF and the metabolism-perfusion ratio. Results 1The radioactive distribution in the normal brain was symmetrical and CGM values were greater than CBF values in every intracerebral structures. 2A total of 267 foci in 87 patients were found and 234 foci with low uptake of FDG, 189 foci with low uptake of ammonia and 2 foci with high uptake of ammonia. Only 7 foci in 7 patients were solitary lesion and the 260 foci in 80 patients displayed multiple and non-symmetrical distribution. 3Abnormal metabolism-perfusion patterns were divided into 5 types:TypeⅠ:matched type with similarly decreased CGM and CBF;Type Ⅱ:slight mismatched type with decreased CGM and normal CBF;Type Ⅲ:slight mismatched type with decreased CBF and normal CGM;Type Ⅳ:markedly mismatched type with severely decreased CGM and mildly decreased CBF;Type Ⅴ:reversed type with decreased CGM and increased CBF. Conclusion The characteristics and patterns from the combination of ¹⁸F-FDG and ¹³N-ammonia brain PET play very important roles in detection and evaluation of ICVD.