目的：急性和慢性视神经炎患者视觉通路的弥散张量成像评估以及视力障碍、视网膜神经纤维层厚度与扩散指数变化的相关性研究。

方法：在26例患者和13例健康对照组中进行扩散张量成像术。患者中17眼患有急性视神经炎，20眼患有慢性视神经炎和15例未受感染眼。所有受试者中，采用神经眼科检查、光学相干断层扫描、视觉诱发电位、眶颅 MRI 等方法对视觉传入系统进行评估。

结果：急性和慢性视神经炎患者视神经中各向异性低于对照组(P=0.28)。急性和慢性视神经炎患者视神经平均扩散率高于患者未受感染眼及对照组(P<0.01)。患者与对照组视网膜神经纤维层厚度、P100 振幅、潜伏期及视力差异均有统计学意义(均P<0.01)。相较于对照组，患者组中视交叉平均扩散率较高(P=0.011)。各组间视束各向异性和平均扩散率测量差异均有统计学意义(分别为P=0.032和P=0.013)。在相关性分析中，急性视神经炎 P100 潜伏期与视神经各向异性相关(r=-0.439，P=0.021)。平均扩散率与视网膜神经纤维层厚度、视力和 P100 潜伏期相关(r=-0.464，-0.334，-0.389； P<0.05)。各向异性与平均扩散率和视力有关，差异均有统计学意义(r=-0.393，0.364； P<0.05)， 而慢性视神经炎的平均扩散系数与 P100 振幅和 RNLF 厚度相关(r=-0.412，-0.374； P<0.05)。视力下降与平均扩散率增加和各向异性下降有关(P<0.05)。

结论：弥散张量成像能够显示眼眶MRI看似正常的组织中的异常。研究结果表明， 弥散张量成像的测量与视觉缺陷和组织损伤相关。

METHODS: We performed DTI in 26 patients and 13 healthy controls. Patients had acute ON in 17 eyes, chronic ON in 20 eyes and 15 unaffected eyes. In all participants, the visual afferent system was evaluated with neuro-ophthalmological examinations, optical coherence tomography(OCT), visual evoked potential(VEP), orbital and cranial MRI.

RESULTS: Fractional anisotropy(FA)in the optic nerves was lower in patients with acute ON and chronic ON than controls(P=0.28). Mean diffusivity(MD)in the optic nerves was higher in patients with acute and chronic ON than the unaffected eyes of patients and controls(P<0.01). Retinal nerve fiber layer thickness, P100 amplitude and latency and visual acuity(VA)were significantly different between patient and control groups(P<0.01). Optic chiasm MD values were higher in the patient group compared to the control group(P=0.011). FA and MD measured in the optic tracts significantly were different between groups(P=0.032, P=0.013, respectively). In the correlation analysis, fractional anisotropy in the optic nerves was correlated with P100 latency in acute ON(P=0.021). Mean diffusivity was correlated with RNFLT, visual acuity and P100 latency(P<0.05). Fractional anisotropy was correlated with mean diffusivity and visual acuity, and, mean diffusivity was correlated with P100 amplitude and RNLF thickness in chronic ON(P<0.05). Reduction in visual acuity was correlated with increase in mean diffusivity and decrease in fractional anisotropy(P<0.05).

CONCLUSION: DTI can demonstrate abnormalities in a tissue that appears normal in orbital MRI. Our results suggested that DTI derived measurements correlate with visual disability and tissue injury and therefore they are important from a clinical point of view and also in understanding the pathological processes.