| 韩鸿宾,高东红.扩散加权像变形矫正技术的相关多因素分析[J].中国医学影像技术,2005,21(8):1271~1274 |
| 扩散加权像变形矫正技术的相关多因素分析 |
| Mutilple factors analysis for the correction of the distortion on diffusion-weighted imaging |
| 投稿时间：2005-04-25 修订日期：2005-05-06 |
| DOI： |
| 中文关键词: 磁共振成像 变形 配准 |
| 英文关键词:Magnetic resonance imaging Distortion Registration |
| 基金项目:本研究为国家自然科学基金资助项目(30170277)。 |
|
| 摘要点击次数: 2306 |
| 全文下载次数: 900 |
| 中文摘要: |
| 目的 探讨扩散加权像变形的矫正模具位置、扩散敏感梯度大小、方向、匀场方式对扩散参数图原始图像变形的影响,为开发矫正装置与方法提供依据。方法 采用自制25点空间定位模具,分别放置在环形极化线圈的中心与偏中心位置,针对每个位置(β因素),在测量前进行主动匀场,在三个垂直方向(α因素)施加b(扩散敏感系数) 为0~1000 s/mm2的Gb,b大小以100 s/mm2步进增加(γ因素)。利用坐标变换得到各图的变形矫正公式,通过多因素方差分析明确各个因素与矫正公式各个系数间的关系。结果 在X,Y方向的变形矫正公式如下:X=X1+X2X'+X3Y'; Y=Y1+Y2X'+Y3Y'。除X3外,各个系数均与方向(α)、位置(β)有关。刚体位移与b值有关。弹性位移与b值(γ)无关(P无显著性差异)。位置(β)与b值(γ)的交互作用影响刚体位移。在扩散敏感系数在700的情况下,Gb s不引起明显的层面内位移, 而Gb r,p主要导致在Y方向的位移。模具中心匀场情况下变形最小。结论 在扩散敏感系数在模具中心匀场700的情况下,Gb r,p的作用主要表现为沿相位编码方向的刚性平移。当取0~1000 s/mm2范围内的其他Gb值时,可以得到同一类型校正公式,只是刚体位移值会不同。匀场情况下,对各个DWI图像的层层对应配准是有效的变形矫正方法。 |
| 英文摘要: |
| Objective To study the effects of different factors on distortion in diffusion-weighted imaging (DWI), the factors including the correction models position, the direction and the value of the diffusion sensitive coefficient, auto-or non auto-shimming. The study was proposed to provide evidents for the investigation of the correction instrument and methods. Methods Self-made space localization phantom with 25 points for correction of the distortion. The phantom was positioned in the center or off-center insides the circle polarized head coil (factor β). Orthogonal (factor α) DWI with b value of 0-1000 s/mm2 (factor γ, with the incremental value of 100 s/mm2 )were performed. Data fitting were performed by using the coordinate shifting functions with the Results of two formulae for the description of the distortion in X and Y direction respectively. The correction of the misregistration was performed between every DWI R,S,P images and the image with b value of 0 s/mm2. ANOVA was performed to clarify the correlation among different factors and every coefficient in the correction formula. Results The correction formulae along X and Y direction were presented as X=X1+X2X'+X3Y'; Y=Y1+Y2X'+Y3Y'. Except X3, every coefficients had great correlation with factorα and β. The rigid transition was significantly correlated with factor (γ), while the elastic translation was not. Factor β andγhad effects on the rigid translation mutually. When b value was set 700, Gb s caused no in-plane distortion, while Gb r, p caused the in-plane rigid transition mainly along the phase-encoding diretion。DWI with the shimming center position showed the least transitions. Conclusion When b value was set 700, Gb r, p Results in the rigid transition mainly along the phase-encoding direction. Under the shimming condition, for every DWIr, p images, the slice to slice registration was effective for the correction of DWI distortions. |
| 查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
