弥散张量成像在急性后部缺血性视神经病变诊断中的应用价值

Diffusion tensor imaging in the diagnosis of acute posterior ischemic optic neuropathy

目的探讨弥散张量成像(DTI)在急性后部缺血性视神经病变(PION)诊断中的应用价值。方法选取30例急性PION患者进行双侧视神经的DTI及视觉诱发电位(VEP)检查,分别测量双眼视神经各向异性分数(FA)、表观扩散系数(ADC)及VEP参数P100潜化期和波幅。采用配对样本t检验对患眼及健眼DTI及VEP参数测量结果进行比较,并采用Pearson分析患眼视神经VEP参数与DTI参数之间的相关性。结果30例急性PION患者患眼视神经的FA及ADC分别为0.383±0.050、(1596.93±144.07)×10^(-6)mm^(2)·s^(-1),健眼视神经的FA、ADC分别为0.636±0.080、(1197.80±93.09)×10^(-6)mm^(2)·s^(-1);与健眼相比,患眼视神经FA明显下降,ADC升高,差异均有统计学意义(t=-14.53、11.54,均为P<0.01)。患眼与健眼VEP参数P100潜伏期分别为(135.38±7.51)ms、(96.76±6.35)ms,波幅分别为(4.79±1.15)μV、(10.05±1.45)μV;与健眼相比,患眼VEP参数P100潜伏期明显延长、波幅明显降低,差异均有统计学意义(t=21.67、-15.19,均为P<0.01)。患眼视神经DTI参数FA与VEP参数P100潜伏期呈负相关(r=-0.540,P<0.01),与P100波幅呈明显正相关(r=0.662,P<0.01);患眼视神经DTI参数ADC与P100波幅呈明显负相关(r=-0.711,P<0.01),与P100潜伏期无相关性(r=0.234,P>0.05)。结论DTI能够早期发现急性PION患者视神经的弥散障碍,能够为其早期诊断提供影像学依据。

Objective To evaluate the application of diffusion tensor imaging(DTI)in acute posterior ischemic optic neuropathy.Methods The fractional anisotropy(FA),apparent diffusion coefficient(ADC),and visual evoked potential(VEP)parameters including P100 latency and amplitude were measured in bilateral optic nerves of 30 patients with acute posterior ischemic optic neuropathy.The results of DTI and VEP of the affected eyes were compared with those of the healthy eyes by paired sample t-tests.Pearson correlation analysis was used to analyze the correlation between the parameters of optic nerve VEP and DTI.Results The FA value and ADC value of the optic nerve in the affected eyes were 0.383±0.050,(1596.93±144.07)×10^(-6)mm^(2)·s^(-1),respectively,and those in the healthy eye were 0.636±0.080,(1197.80±93.09)×10^(-6)mm^(2)·s^(-1),respectively.Compared with the healthy eyes,the FA value of the optic nerve in the affected eyes decreased significantly,while the ADC value increased,and the differences were statistically significant(t=-14.53,11.54,both P<0.01).The P100 latencies of VEP were(135.38±7.51)ms and(96.76±6.35)ms,and the P100 amplitudes of VEP were(4.79±1.15)μV and(10.05±1.45)μV in affected eyes and healthy eyes,respectively.The P100 latencies of VEP of the affected eyes significantly prolonged and the P100 amplitude of VEP significantly decreased compared with the healthy eyes,and the differences were statistically significant(t=21.67,-15.19,both P<0.01).In the affected eyes,the FA value was negatively correlated with P100 latencies of VEP(r=-0.540,P<0.01),and positively correlated with the P100 amplitude of VEP(r=0.662,P<0.01).In the affected eyes,the ADC value of optic nerve was negatively correlated with the P100 amplitude of VEP(r=-0.711,P<0.01),and was not correlated with the P100 latencies of VEP(r=0.234,P>0.05).Conclusion DTI can early detect the optic nerve diffusion disorder of posterior ischemic optic neuropathy and provide imaging evidence for its early diagnosis.