巨噬细胞活性MRI对多发性硬化大鼠模型中枢神经系统病灶诊断价值的初步研究

目的 探讨巨噬细胞活性成像(MAI)对多发性硬化(MS)模型大鼠脑和脊髓病灶的诊断价值.方法 20只正常Lewis大鼠用数字表法随机分成实验组15只,对照组5只.应用髓鞘少突胶质细胞糖蛋白多肽35-55(MOG35-55)致敏实验组大鼠制备MS动物模型实验性自身免疫性脑脊髓炎(EAE),大鼠首次急性发病后第3天行MR检查.分别对大鼠脑和脊髓行T2WI、T1WI和Gd-DTPA增强T1WI的三维容积扫描.经大鼠尾静脉注入超微超顺磁性氧化铁(USPIO)24 h后行USPIO增强T2WI(即MAI).利用工作站专业软件获得大鼠脑和脊髓冠状面、横断面和矢状面的重组图像,并与常规图像进行比较.结果 成功建立MOG35-55-EAE模型大鼠15只.MOG35-55-EAE大鼠急性发病期相关的中枢神经系统病灶多数分布在脑内(58/63),少数位于脊髓(5/63).常规MRI上病灶表现为T2WI高信号、T1WI低信号,部分出现Gd-DTPA强化.在MAI图像上病灶呈低信号,部分USPIO强化病灶在T2WI上呈等信号,病灶的USPIO强化与Gd-DTPA强化表现不完全一致.T2WI(14/15)和MAI(13/15)对MOG35-55-EAE大鼠急性期病灶的敏感度高,两者联合对病灶的检出率高达100%(15/15),增强T1WI的敏感度相对较低(7/15).对照组大鼠MAI未见异常.结论 MAI弥补传统MR检查技术的不足,能监测EAE的炎症反应,与常规T2WI联合能提高MOG35-55-EAE大鼠病灶的检出率;Gd-DTPA增强能显示EAE血脑屏障破坏的早期活动性病灶,MAI与之联合成像对EAE病灶的诊断和监测有互补作用.

Diagnostic value of macrophage activity MRI in rat model of multiple sclerosis

Objective To investigate the value of macrophage activity imaging (MAI) in the diagnosis of brain and spinal cord lesions in rat model of multiple sclerosis(MS). Methods Twenty LEW rats were divided into 15 model rats and 5 control rats. MS animal model, experimental autoimmune encephalomyelitis (EAE) was induced by the injection of peptide 35-55 of myelin oligodendrocyte glycoprotein ( MOG35-55 ). MRI was performed on the third day of the acute stage of disease. The brain and spinal cord of rats were scanned by 3.0 T MR scanner( Siemens Trio Tim) with quadrature wrist joint coil.The T2W and T1 W images, Gadolinium enhanced T1 W images in 3D volume were obtained respectively. The MAI were obtained at 24 hours after intravenous injection of ultra small superparamagnetic iron oxide (USPIO) as contrast medium on T2WI. The workstation with special software was used for the reconstruction images of brain and spinal cord of rat in multiple orientations. Results Fifteen MOG35-55-EAE rats model of MS were successfully induced. The great majority lesions of central nervous system in acute stage were located in the brain( 58/63 ) and less in the spinal cord (5/63). The main manifestation of EAE lesions presented was hyperintensity on T2 WI and hypointensity on T1 WI, and some lesions had enhancement after Gd-DTPA injection. The EAE lesions presented as hypointensity on MAI images, but some of them were found to be isointensity on T2 WI. The enhancement pattern was discrepant between USPIO and Gd-DTPA.The sensitivity of depicting lesions of MOG35-55-EAE rat at acute stage were higher on T2WI ( 14/15 ) and MAI ( 13/15 ), and the detection rate was 100% ( 15/15 ) if they were combined. Gd-DTPA enhanced T1 WI had a lower sensitivity (7/15). All the MAI findings were negative in the control rats. Conclusions MAI can complement the drawback of conventional MRI techniques by continuously monitoring the inflammatory activity of EAE lesions, and it could raise the detection rate of EAE lesions by combining with T2WI. Gd-DTPA enhanced T1 WI monitors the breakdown of the blood brain barrier. MAI and Gd-DTPA enhanced MR imaging are complementary in the diagnosis and monitoring of EAE lesions.