Three-dimensional analysis of white matter tracts using multishot diffusion-weighted MR imaging

由扩散张量成像得到的分数各向异性(FA)图显示了白质束的扩散各向异性。由于丰富的白质纤维聚集并向同一方向运动的部分信号变得很高，因此可以看到白质束。当连续3 mm厚的128x128矩阵的FA图可显示锥体束、小脑中脚、大脑脚、内囊、胼胝体等。在41例正常受试者中，延髓锥体束和上、中、下小脑脚三维清晰可见。在13例对照组中，10例经基因检测确诊的脊髓小脑变性患者(SCA 1期3例，SC 3期3例，DRPLA期4例)和5例典型临床诊断的多系统萎缩(MSA)患者行弥散张量成像。术后计算表观弥散系数(ADC)图和FA图，进行形态测量，测量ADC值和FA值，FA和ADC值较形态测量更敏感。与对照组相比，小脑脚内侧的SCA-1和桥脑的DRLA的ADC值显著升高，而FA值无明显变化。在OPCA患者中，小脑脚中部和桥脑的ADC值升高，FA值下降，差异有统计学意义。最后，我们成功地进行了三维成像，并利用弥散张量成像的ADC值和FA值确定了其在脊柱小脑变性中的临床应用价值。虽然我们没有收集到足够的临床数据，但建立基础研究方法是有价值的。进一步的检查将产生新的发现和临床发展。

Fraction anisotropy (FA) map obtained by the diffusion tensor imaging shows diffusion anisotropy of the white matter tracts. Since a signal becomes high in the portion with which rich white matter fibers crowd and run same direction, white matter tract can be visualized. When continuous 3 mm thick FA maps with 128x128 matrix are available, we can make a 3D-tractography which shows pyramidal tract, middle cerebellar peduncle, cerebral peduncle, internal capsaule, corpus callosum, and so on. Indeed, in 4l normal subjects, the pyramidal tract at medulla oblongata and the superior, middle, and inferior cerebellar peduncle were clearly visible in three dimensions.In 13 control subjects, 10 patients with spinocerebellar degeneration (3 with SCA 1, 3 with SC 3, 4 with DRPLA) diagnosed by gene inspectien, and 5 with multi-system atrophy (MSA) diagnosed from typical clinical condition, diffusion tensor images were obtained. Aftar Apparent Diffusion Coefficient (ADC) map and FA map were calculated, morphological measurement was performed, and the ADC value and FA value were measured.FA and ADC value are more sensitive than morphological measurement to detect the degeneratien of white matter tracts. In compared with the control group, the ADC value rose significantly in SCA 1 at the middie cerebellar peduncle and in DRPLA at the pons, whereas the FA values showed no significant change. In patients with OPCA, the ADC value rose and FA value fell at both the middle cerebellor peduncle and the pons with the statistically differences.Finally, we succeeded to make 3D-tractography and to establish the clinical usefulness in spinocerebella degeneration by using the ADC value and FA Value of a diffusion tensor imaging. It is valuable to establish the fundamental research technique, although we did not collect enough clinical date. The further examinations will produce new findings and a clinical development.