盲眼患者视神经和视放射磁共振扩散张量成像观察

Magnetic resonance diffusion tensor imaging for optic nerves and optic radiation in blind patients

目的 观察盲眼患者视觉传导通路中视神经和视放射磁共振扩散张量（MRDTI）扫描像特征。方法对20例盲眼患者（盲眼组）和20名正常健康者（对照组）行视神经和视放射MR—DTI扫描。应用Volumeone1．72软件进行后处理，获得黑白各向异性（FA）和方向编码彩色（DEC）图。观察视神经和视放射在FA和DEC图中的信号表达。在DEC图上分别测量并对比分析盲眼组和对照组受检者双侧视神经和视放射的FA、平均扩散率（MD）、本征矢量λ∥及λ⊥值。结果对照组双侧视神经在FA和DEC图均呈高信号，盲眼组双侧视神经在FA和DEC图均呈明显低信号。盲眼组视神经FA和λ∥值均较对照组明显降低，差异有统计学意义（t=16．294，14．660；P值均=0．000）；MD和λ⊥值均较对照组明显升高，差异也有统计学意义（t=8．096，8．538；P值均=0．000）。两组受检者双侧视放射在FA和DEC图均呈高信号。盲眼组与对照组双侧视放射FA和MD值比较，差异均无统计学意义（左侧：t=1．456、1．811，P=0．152、0．076；右侧：t=0．779、0．073，P=0．440、0．942）。结论盲眼患者双侧视神经MR—DTI呈低信号，双侧视放射MR—DTI呈高信号。

Objective To observe the characteristics of magnetic resonance diffusion tensor imaging （MR DTI）for optic nerves and optic radiation in blind patients. Methods The optic nerves and optic radiation of 20 blind patients（blind group）and 20 controLs（control group） were scanned by MR-DTI. Fractional anisotropy （FA） and directional encoded color （DEC） maps were acquired through post processing with the aid of volume-one ]. 72 software. The signal intensity of optic nerves and optic radiation were then observed. The FA, mean diffusivity （MD）, λ∥ and λ⊥ value of bilateral optic nerves and optic radiation in two groups were measured in the DEC maps. Results While the high signal intensity was found in bilateral optic nerves in FA and DEC maps in control group, the signal decreased markedly in the blind group. The FA and λ∥ value of optic nerves in the blind group were declined obviously compared to that in the control group. The difference was statistically significant （t=16. 294, 14. 660;P=0. 000）. The MD and λ⊥ value of optic nerves in the blind group were increased obviously compared to that in the control group, the difference was also statistically significant （t= 8. 096, 8. 538; P= 0. 000）. The high signal intensity was found in bilateral optic radiation in FA and DEC maps in both the blind and control groups. There were no statistic differences in FA and MD value in bilateral optic radiation between the blind and control groups （Left：t=1.456,1.811;P=0. 152,0.076. Right：t=0. 779,0. 073;P=0.440,0. 942）. Conclusion A low signal intensity of bilateral optic nerves and a high signal intensity of bilateral optic radiation were found in blind patients.