癫痫患者脑PET异常、MRI正常的分析

Analysis of abnormal metabolism on ^(18)F-FDG PET with normal structure on MRI in epilepsy

目的再认识原发性癫痫病灶脑18F-FDGPET异常、MRI正常图像。方法仪器为GE Discovery LS PET/CT和Philips1.5T磁共振。选取PET提示代谢异常而MRI显示正常的癫痫患者共87例,男60例,女27例,平均年龄20岁。结果87例PET提示18F-FDG代谢异常在MRI相应区域出现脑沟裂轻度增宽者39例,占44.8%。39例均为FDG低代谢,其中5例注射显像剂前一小时癫痫发作。结论原发性癫痫PET出现低代谢改变者已有44.8%的患者在MRI图像上存在肉眼可见的局部脑沟裂轻度增宽表现,这一病理基础也可能是导致癫痫发作期仍表现为低代谢的原因。

Objective To compare the results of brain ^18F-FDG PET and MRI in epileptic patients and to find the existed anatomical change of MRI based on ISF-FDG PET findings. Methods Eight-seven patients were selected according to the results of abnormal metabolism on PET and normal structure on MRI （male 60, female 27, mean age 20 years with range 4- 50 years, suffering age 10. 5 years with range 0.5-34 years）. PET/CT and MRI brain scanning was performed using GE Discovery LS PET/CT and Philips 1.5T MR scanner. Firstly, all images of PET/CT and MRI were judged by two qualified doctors double-blindly. Then, Comparative evaluation of PET and MRI were performed slice by slice by PET/CT and MRI doctors working together. PET diagnostic criteria： abnormal metabolism of PET was based on FDG accumulation increase or decrease of 150% in two consecutive slices compared with the contralateral corresponding zone on the same patient. Anatomical abnormity of MRI was estimated visually by doctors. Results ①Carefully reviewed negative images on MRI based on positive image findings on PET we found that the brain sulcus was visually wider in corresponding area on MRI in 39 patients （44.8%）. ②Imaging characteristic： all 39 patients were shown hypometabolism though 5 of them were seizures before examination in one hour. Regarding the metabolic sites, 9 patients were located in the temporal lobe, 13 in the frontal, parietal or occipital lobe, and 17 patients were shown multiple lesions or located in the two sides. Conclusion Comparative analyzing PET images with MRI slice by slice suggested that there were some brain sulcus change already existed on negative MRI based on PET metabolic abnormality change. This may be the one of the reasons to explain the hypometabolism on PET at seizure onset.