使用点弥散函数模型法校正扩散频谱影像內磁化率差异引致影像扭曲的效力评估

波谱学杂志 ›› 2010, Vol. 27 ›› Issue (3): 379-385.

使用点弥散函数模型法校正扩散频谱影像內磁化率差异引致影像扭曲的效力评估

徐泳钦¹，许靖涵¹，曾文毅^2*

1. 清华大学生医工程与环境科学系，台湾新竹 300; 2. 台湾大学附设医院生医光电中心暨影像医学部，台湾台北 100

收稿日期:2010-07-14 出版日期:2010-09-05 发布日期:2010-09-05

Evaluation of Diffusion Spectrum Imaging Tractography after Susceptibility-Induced Distortion Correction by Model-Based Point Spread Function Method

HSU YUNG-Chin¹, HSU Ching-Han¹, TSENG Wen-Yih Isaac²

1. Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 300;
2. Center for Optoelectronic Biomedicine and Department of Medical Imaging, National Taiwan University College of Medicine and Hospital, Taipei 100

Received:2010-07-14 Online:2010-09-05 Published:2010-09-05

摘要/Abstract

摘要：

平面回波影像 (EPI) 常常在额叶、颞叶或脑干处出现严重的影像扭曲. 目前已有数种方法可校正这种由磁化率差异造成的影像扭曲，该文提出一种简单有效的方法叫点弥散函数模型法. 由纤维追踪的角度来探讨影像扭曲校正的有效性. 评估的方法是将点弥散函数模型法应用于扩散频谱影像，并比较由扭曲影像与校正影像所得之扣带回纤维数目的多寡. 定义了一个指标用来量化影像扭曲校正的有效性：r =(N_c-N_d)/(N_c+N_d)，此值越大代表校正影像的纤维追踪结果越好. 对于左扣带回与右扣带回，其r 值分别为0.424±0.452(平均±标准差)及0.343±0.452，且在统计上皆显著大于零. 结果显示，就左右扣带回而言，校正后的影像其纤维追踪的结果较扭曲影像更佳. 因此，将点弥散函数模型法应用于校正扩散频谱影像的扭曲可增进左右扣带回的纤维追踪的结果.

关键词: 磁化率导致影像扭曲, 弥散函数模型法, 扩散频谱影像, 扣带回

Abstract:

Echo-planar imaging suffers from susceptibility-induced distortion in the frontal lobe, temporal lobe and brain stem regions. To correct for the distortion, recently we proposed an easy-implemented and effective method called model-based point spread function (PSF) method. This study aimed to investigate the effectiveness of distortion correction from the perspective of fiber tracking. The evaluation was carried out by applying the modelbased PSF method on diffusion spectrum imaging (DSI) dataset and comparing the number of cingulum tracts generated from the distorted DSI dataset and the corrected DSI dataset. An index representing the effectiveness of distortion correction was defined as: r=(N_c-N_d)/(N_c+N_d), where N_c and N_d were, respectively, the number of tracts generated from DSI dataset after distortion correction and that without correction. For the left and right cingulum bundles, the ratios of the effectiveness of distortion correction were 0.424±0.452 (mean±SD) and 0.343±0.452, respectively. In addition, the ratios of both cingulum bundles were significantly greater than zero, indicating that the tracking results after distortion correction were better than those without correction. In conclusion, our results suggest that application of distortion correction on DSI dataset using the model-based PSF method can significantly improve the fiber tracking results.

Key words: susceptibility-induced distortion, model-base PSF method, diffusion spectrum imaging, cingulum bundles

中图分类号:

R445.2

徐泳钦, 许靖涵, 曾文毅. 使用点弥散函数模型法校正扩散频谱影像內磁化率差异引致影像扭曲的效力评估[J]. 波谱学杂志, 2010, 27(3): 379-385.

HSU YUNG-Chin, HSU Ching-Han, TSENG Wen-Yih Isaac. Evaluation of Diffusion Spectrum Imaging Tractography after Susceptibility-Induced Distortion Correction by Model-Based Point Spread Function Method[J]. Chinese Journal of Magnetic Resonance, 2010, 27(3): 379-385.

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