MR扩散张量成像对健康成人视放射纤维束的初步研究

Preliminary study of the optic radiation in healthy adults by MR diffusion tensor imaging

目的探讨健康成人视放射白质纤维束分布及视放射Meyer袢变异情况。方法选取25名健康志愿者进行头部MR扫描，获得DTI资料。然后采用DTI Studio软件行图像后处理，结合多个ROI方法重建图像。测量左、右侧视放射Meyer袢远端与颞极距离（MT）值及左、右侧视放射纤维束区的各向异性分数（FA）值。左、右两侧MT值、FA值的比较行配对t检验。结果25名志愿者共重建出49个视放射纤维束，MT值为（43．2±7．7）mm（范围为30．6—59．7mm），变异系数18％。左、右两侧视放射纤维束的MT值分别为（43．5±8．1）、（43．2±7．5）mm，FA分别为0．53±0．10、0．53±0．07，差异均无统计学意义（t值分别为0．12、0．00，P值分别为0．91、1．00）。结论视放射Meyer袢MT值变异较大，可以作为预测颞叶切除术后视野缺损的重要指标。

Objective To investigate the distribution of optic radiation fibers and the variation of Meyer loop in healthy adults. Methods Diffusion tensor magnetic resonance images were obtained from 25 healthy volunteers using a 1.5 T MR scanner and postprocessed using the DTI Studio software. Multiple ROIs were used for fiber reconstruction. The distance between the anterior limit of Meyer loop and the temporal tip（MT） and the fraction of anisotropy （FA） at one side were compared with those at the contralateral side by paired t test. Results Forty-nine optic radiation fibers were successfully reconstructed in 25 volunteers. The value of MT was （43.2 ±7. 7） mm（ranged from 30. 6 to 59. 7 mm）, and coefficient of variation was 18%. The values of MT and FA of optic radiation in the left side were （43. 5 ± 8. 1 ） mm, （0. 53 ± 0. 10） respectively, and those counterparts in the right side were （43.2 ± 7. 5） nun and （0. 53 ± 0.07） respectively. There were no significance difference of MT or FA between the two sides （ t = 0. 12, 0. 00 ;P = 0. 91 and 1.00 respectively）. Conclusions The range of interindividual variation for MT was rather large in healthy volunteers. The preoperative measurement of the MT appears be helpful to predict the risk of the incidence of visual defect and to decrease the incidence of the complication.