CAJ | 학술논문

为研究非正定矩阵对水分子扩散张量导出量的影响.提出了一种计算扩散张量导出量的优化算法.采集5位健康志愿者脑部磁共振扩散张量图像,沿25个方向施加强度为40 mT/m的扩散敏感梯度磁场,扩散权重值为1000s/mm2,求解超定方程,得到了各体素的二阶扩散张量.在灰质区域非正定矩阵较少,在胼胝体的膝部和压部发现大量非正定矩阵.由于这些非正定矩阵的影响,使用常规算法得到的平均扩散率和各向异性分数分别被低估和高估.为此修正了常规算法,使用矩阵特征值的绝对值计算扩散张量导出量.结果表明,由修正算法得到的扩散张量导出量图像的鲁棒性及可靠性均得到提高.
위연구비정정구진대수분자확산장량도출량적영향.제출료일충계산확산장량도출량적우화산법.채집5위건강지원자뇌부자공진확산장량도상,연25개방향시가강도위40 mT/m적확산민감제도자장,확산권중치위1000s/mm2,구해초정방정,득도료각체소적이계확산장량.재회질구역비정정구진교소,재변지체적슬부화압부발현대량비정정구진.유우저사비정정구진적영향,사용상규산법득도적평균확산솔화각향이성분수분별피저고화고고.위차수정료상규산법,사용구진특정치적절대치계산확산장량도출량.결과표명,유수정산법득도적확산장량도출량도상적로봉성급가고성균득도제고.
To evaluate the effect of the positive-indefinite matrix on the diffusion tensor-derived parameters,a modified algorithm is proposed for calculating these parameters.Magnetic resonance (MR) diffusion tensor im-ages of five healthy volunteers are collected.The diffusion sensitive gradient magnetic fields are applied along 25 directions and the diffusion weighting value is 1000 s/mm2.Many positive-indefinite diffusion tensors can be found in the white matter area,such as the genu and the splenium of corpus callosum.Due to the positive-indefi-nite matrix,the mean diffusivity (MD) and the fractional anisotropy (FA) are under-estimated and over-estimat-ed by using the conventional algorithm.Thus,the conventional algorithm is modified by using the absolute values of all eigenvalues.Results show that both the robustness and the reliability for deriving these parameters are im-proved by the modified algorithm.