Diffusion tensor fiber tractography of the optic radiation: analysis with 6-, 12-, 40-, and 81-directional motion-probing gradients, a preliminary study.
Diffusion tensor fiber tractography of the optic radiation: analysis with 6-, 12-, 40-, and 81-directional motion-probing gradients, a preliminary study.
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发表时间：
2007
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通讯作者：
A. Yamamoto;Y. Miki;S. Urayama;Y. Fushimi;Tsutomu Okada;T. Hanakawa;H. Fukuyama;K. Togashi
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作者：
A. Yamamoto;Y. Miki;S. Urayama;Y. Fushimi;Tsutomu Okada;T. Hanakawa;H. Fukuyama;K. Togashi
背景与目的术前准确掌握视放射线的位置对颞叶手术有重要意义。我们假设，更多的运动探测梯度（MPG）将提供更好的结果的扩散张量（DT）纤维束成像的光学辐射。为了验证这一假设，本研究评估了不同MPG设置下DT纤维束成像的视辐射差异。方法12例健康志愿者（男7例，女5例），年龄22-45岁，平均32岁。采用3 T MR成像仪，单次激发回波平面成像，并行采集（缩减因子= 2），获得DT图像。在6、12、40和81个独立方向施加MPG。第一个感兴趣区域（ROI）位于枕叶，第二个ROI位于外侧膝状体。穿透两个ROI的光纤被认为是光学辐射。将轴向切面上Meyer袢尖端与外侧膝状体之间的前后距离定义为袢指数。统计学评价两大脑半球的纤维数目和环指数。结果DT纤维束成像显示24侧半球中20侧（83%）的视放射线显示良好。不同MPG设置之间的纤维数量和袢指数无显著差异。结论DT纤维纤维束成像技术可频繁地显示几乎全部的视神经辐射。MPG数对视觉辐射的可视化没有任何显著影响，因此6方向MPG足以达到此目的。
BACKGROUND AND PURPOSE Knowing the exact location of the optic radiation preoperatively is important for surgery of the temporal lobe. We hypothesized that a greater number of motion-probing gradients (MPGs) would provide better results of diffusion tensor (DT) fiber tractography of the optic radiation. To test this hypothesis, this study evaluated differences in DT fiber tractography of the optic radiation under different MPG settings. METHODS DT images were obtained in 12 healthy volunteers (7 men, 5 women) with a mean age of 32 years (range, 22-45 years) by using a 3T MR imaging scanner with single-shot echo-planar imaging with parallel acquisition (reduction factor = 2). MPG was applied in 6, 12, 40, and 81 independent directions. The first region of interest (ROI) was placed in the occipital lobe, and the second ROI was placed in the lateral geniculate body. Fibers penetrating both ROIs were considered as the optic radiation. Anteroposterior distance between the tip of the Meyer loop and the lateral geniculate body on an axial section was defined as a loop index. Numbers of fibers and loop indices in both cerebral hemispheres were evaluated statistically. RESULTS The optic radiation was well visualized in full length by DT fiber tractography in 20 of 24 hemispheres (83%). No significant differences were noted in number of fibers and loop indices among different MPG settings. CONCLUSION DT fiber tractography can frequently depict almost the entire optic radiation. MPG number does not exert any significant effect on visualization of the optic radiation, and 6-directional MPG is thus sufficient for this purpose.