视神经脊髓炎视觉通路磁共振弥散张量成像与视觉诱发电位的相关性研究

STUDY ON RELATIONSHIP BETWEEN DIFFUSION TENSOR IMAGING AND VISUAL EVOKED POTENTIAL IN VISUAL PATHWAY OF NEUROMYELITIS OPTICA

目的通过弥散张量成像(diffusion tensor imaging,DTI)技术定量研究视神经脊髓炎(neuromyelitis optica,NMO)患者脑白质纤维隐匿性病变与视觉诱发电位(visual evoked potential,VEP)P100波潜伏期的相关性。方法将2008年7月-2009年4月收治并符合选择标准的20例NMO患者作为试验组,根据患者VEP检查提示P100波潜伏期是否延长,将其分为VEP异常组(试验组1)和VEP正常组(试验组2);以20例健康成人志愿者作为对照组。各组行头颅DTI,视神经、视束、视放射部位部分各向异性(fractional anisotropy,FA)值(对应为FAn、FAt及FAr)和平均弥散率(mean diffusivity,MD)值(对应为MDn、MDt及MDr)测量。比较各组FA、MD值及P100波潜伏期;对NMO患者FA、MD值与P100波潜伏期进行相关性分析。结果试验组20例NMO患者中,13例VEP检查双侧P100波潜伏期延长或波形未引出,作为试验组1;7例双侧P100波潜伏期正常,作为试验组2。与试验组2及对照组比较,试验组1各部位FA值显著降低,MD值显著升高,比较差异均有统计学意义(P<0.05);试验组2各部位FA值及MD值与对照组比较,差异均无统计学意义(P>0.05)。NMO患者各部位FA值与P100波潜伏期成负相关(P<0.05),各部位MD值与P100波潜伏期成正相关(P<0.05)。结论 DTI技术可发现VEP异常的NMO患者在MRI表现正常的视路脑白质纤维的细微病变,NMO患者视觉传导通路DTI参数与VEP存在相关性,提示可通过MRI和VEP的临床指标对病情及预后进行评估。

Objective To study the relationship between brain white matter fiber occult lesions and P100 wave latency of visual evoked potential（VEP） in neuromyelitis optica（NMO） patients by diffusion tensor imaging（DTI）.Methods Twenty patients with NMO who were treated between July 2008 and April 2009 were selected as the trial group. According to the VEP test, the latency of P100 wave was prolonged, the NMO patients were divided into VEP abnormal group（trial group 1） and VEP normal group（trial group 2）. Twenty healthy adult volunteers served as the control group. The DTI examination in brain was done to measure the fractional anisotropy（FA） value of optic nerve（FAn）, optic tract（FAt）, and optic radiation（FAr）; and the mean diffusivity（MD） value of optic nerve（MDn）, optic tract（MDt）, and optic radiation（MDr）. The FA, MD, and P100 wave latency were compared between groups, and the correlation between MD, FA, and P100 wave latency of NMO were analyzed. Results In the 20 NMO patients, 13 patients with VEP had prolonged bilateral P100 wave latency prolongation or no wave（trial group 1）, and 7 patients had normal bilateral P100 wave latency（trial group 2）. Compared with the trial group 2 and the control group, the FA values were significantly decreased, and the MD values were significantly increased in the trial group 1（P〈0.05）. There was no significant difference in the FA and MD values between the trial group 2 and the control group（P〈0.05）. All FA（FAn,FAt, and FAr） values of each part of NMO patients were negatively correlated with the latency of P100 wave（P〈0.05）, all MD（MDn, MDt, and MDr） values were positively correlated with the latency of P100 wave（P〈0.05）. Conclusion DTI could show small pathylogical changes in the white matter fibers of visual pathway, and there is a correlation between DTI and VEP in NMO, suggesting that a more comprehensive assessment to the condition and prognosis can be made through the VEP in the clinical indicators.