School of Medicine, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD 20892, USA.
J Neuroimaging. 2011 Apr;21(2):e41-9. doi: 10.1111/j.1552-6569.2010.00468.x.
Visual disability is common in multiple sclerosis, but its relationship to abnormalities of the optic tracts remains unknown. Because they are only rarely affected by lesions, the optic tracts may represent a good model for assessing the imaging properties of normal-appearing white matter in multiple sclerosis.
Whole-brain diffusion tensor imaging was performed on 34 individuals with multiple sclerosis and 26 healthy volunteers. The optic tracts were reconstructed by tractography, and tract-specific diffusion indices were quantified. In the multiple-sclerosis group, peripapillary retinal nerve-fiber-layer thickness and total macular volume were measured by optical coherence tomography, and visual acuity at 100%, 2.5%, and 1.25% contrast was examined.
After adjusting for age and sex, optic-tract mean and perpendicular diffusivity were higher (P=.002) in multiple sclerosis. Lower optic-tract fractional anisotropy was correlated with retinal nerve-fiber-layer thinning (r=.51, P=.003) and total-macular-volume reduction (r=.59, P=.002). However, optic-tract diffusion indices were not specifically correlated with visual acuity or with their counterparts in the optic radiation.
Optic-tract diffusion abnormalities are associated with retinal damage, suggesting that both may be related to optic-nerve injury, but do not appear to contribute strongly to visual disability in multiple sclerosis.
多发性硬化症患者中常见视力障碍，但视神经束异常与其的关系尚不清楚。由于视神经束很少受到病变的影响，因此它们可能是评估多发性硬化症正常外观白质成像特性的良好模型。
对 34 名多发性硬化症患者和 26 名健康志愿者进行全脑弥散张量成像。通过示踪技术重建视神经束，并量化束特异性弥散指数。在多发性硬化症组中，通过光学相干断层扫描测量视盘周围视网膜神经纤维层厚度和黄斑总体积，并检查 100%、2.5%和 1.25%对比度的视力。
调整年龄和性别后，多发性硬化症患者的视神经束平均和垂直弥散度更高（P=.002）。较低的视神经束各向异性分数与视网膜神经纤维层变薄（r=.51，P=.003）和黄斑总体积减少（r=.59，P=.002）相关。然而，视神经束弥散指数与视力或视辐射中的相应指标并无特异性相关。
视神经束弥散异常与视网膜损伤相关，表明两者可能与视神经损伤有关，但似乎对多发性硬化症中的视力障碍没有重要影响。
