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

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。由于信号在与丰富的白质纤维聚集并向同一方向运行的部分变得高，因此可以看到白质束。当有连续3mm厚的128 × 128矩阵FA图时，我们可以制作三维神经束图，显示锥体束、小脑中脚、脑脚、内囊、胼胝体等。事实上，在41名正常受试者中，延髓锥体束和小脑脚上、中、下三维清晰可见。对照13例，10例经基因检测诊断为脊髓小脑变性（scs1型3例，sc3型3例，DRPLA型4例），5例经典型临床诊断为多系统萎缩（MSA），获得弥散张量图像。计算表观扩散系数（ADC）图和FA图后，进行形态学测量，测定ADC值和FA值。FA和ADC值对脑白质束变性的检测比形态学检测更灵敏。与对照组相比，小脑中脚SCA 1和桥脑桥DRPLA的ADC值显著升高，FA值无显著变化。OPCA患者小脑中蒂和桥脑的ADC值升高，FA值下降，差异有统计学意义。最后，我们成功地利用弥散张量成像的ADC值和FA值进行了三维神经束造影，并建立了脊髓小脑变性的临床应用价值。虽然我们没有收集足够的临床数据，但建立基础研究技术是有价值的。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.