DIT与BOLD-fMRI技术对屈光不正性弱视皮层损害机制的研究  

Study on the mechanism of cortical deficit in people with ametropic amblyopia by DTI and BOLD-fMRI

作　　者：郭明霞[1] 张云亭[1,2] 张权[2] 李威[2] 

机构地区：[1]天津医科大学医学影像学系,天津300203 [2]天津医科大学总医院放射科

出　　处：《中国实用眼科杂志》2007年第1期27-30,共4页Chinese Journal of Practical Ophthalmology

摘　　要：目的基于大脑各皮层区的功能动力学特征受到皮层间及皮层外解剖结构连接制约的观点，探讨屈光不正性弱视视觉皮层功能损害与胼胝体、视辐射发育不良的关系。方法利用弥散张量成像（DTI）及纤维跟踪技术（DTT）比较30例屈光不正性弱视患者与30例正常人胼胝体、视辐射各向异性分数（FA）值和平均弥散系数（DCavg）值，及神经纤维投射方式；并对屈光不正性弱视组和正常组各10例行血氧水平依赖的功能性磁共振成像（BOLD-fMRI），分别在平面与立体图刺激下比较视皮层激活水平。结果与正常组比较，屈光不正性弱视组背侧视皮层区域激活范围与强度显著低于正常组，胼胝体体部DCavg值显著高于正常组，视辐射FA值显著低于正常组，连接枕叶与顶枕联合皮层的胼胝体纤维数与视辐射纤维数明显减少。结论胼胝体后部和视辐射发育不良，视皮层神经元活动减少或神经元同步化活动减少可能是弱视视皮层功能损害的主要机制。Objective The functional dynamics within segregated cortical areas are believed to be constrained by both intrinsic and extrinsic anatomical connections. The objective of this study was to investigate the relationship between functional deficit of visual cortex and disruption in callosal and optic radiation development in human ametropic amblyopia. Methods The fractional anisotropy （FA）,average diffusion coefficient （DCavg）, neural fiber tracts of corpus callosum and optic radiations between 30 persons with ametropic amblyopia and 30 healthy ones were compared by diffusion tensor imaging （DTI） with tractography （DTT）; The visual cortical activity induced by plane-and stereo-figure in 10 of the 30 ametropic amblyopic persons and 10 of the 30 healthy ones were compared by use of blood oxygenation level dependent-functional magnetic resonance imaging（BOLD-fMRI）. Results The activation in the regions of dorsal visual cortex decreased or disappeared in ametropic amblyopic group compared with the normal group, DCavg values in the body of corpus callosum was higher,And FA values in bilateral optic radiations were lower.AU these results have statistical significance and coincide with the decreased neural fibers of the optic radiations, body and splenium of corpus callosum. Conclusions The disruption in the development of corpus callosum, optic radiations and the reduced activity of the neurons or reduce synchronization among aetivity neurous in visual cortex may be major causes of visual cortical deficit in people with ametropic amblyopia.

关 键 词：屈光不正性弱视 功能磁共振成像 弥散张量成像 纤维跟踪技术 皮层激活 

分 类 号：R777.44[医药卫生—眼科]