High-resolution diffusion-weighted imaging with interleaved variable-density spiral acquisitions
High-resolution diffusion-weighted imaging with interleaved variable-density spiral acquisitions
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DOI：
10.1002/jmri.20287
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发表时间：
2005-04-01
影响因子：
4.4
通讯作者：
Moseley, ME
中科院分区：
文献类型：
--
作者：
Li, TQ;Kim, DH;Moseley, ME
目的：开发一种用于脑部亚毫米面内分辨率弥散加权成像(DWI)的多脉冲磁共振成像(MRI)脉冲序列及重建算法。材料与方法：在临床MRI扫描仪上实现了一种基于变密度螺旋k空间轨迹设计的自导航多脉冲采集技术。该图像重建算法利用了中心k空间的过采样，并将k空间数据的密集采样中心部分用于成像重建和运动校正。在琼脂凝胶模体和三名健康志愿者身上测试了所开发的DWI技术。结果：运动导致多次螺旋采集的DWI数据的相移和k空间移动。通过二维自导航校正，在8~32行交错扫描条件下，获得了分辨率为0.9×0.9×3 mm(3)的扩散加权图像。实验测得均匀凝胶体模的表观扩散系数(ADC)为(1.66+/-0.09)×10(-3)mm(2)/s，与文献值吻合较好。结论：自导航多炮变密度螺旋采集技术为临床获取高分辨率扩散加权图像提供了一种时效性强的方法。基于运动校正的k-空间数据重建算法具有较强的鲁棒性，测量的ADC值准确且可重复性好。
Purpose: To develop a multishot magnetic resonance imaging (MRI) pulse sequence and reconstruction algorithm for diffusion-weighted imaging (DWI) in the brain with sub-millimeter in-plane resolution.Materials and Methods: A self-navigated multishot acquisition technique based on variable-density spiral k-space trajectory design was implemented on clinical MRI scanners. The image reconstruction algorithm takes advantage of the oversampling of the center k-space and uses the densely sampled central portion of the k-space data for both imaging reconstruction and motion correction. The developed DWI technique was tested in an agar gel phantom and three healthy volunteers.Results: Motions result in phase and k-space shifts in the DWI data acquired using multishot spiral acquisitions. With the two-dimensional self-navigator correction, diffusion-weighted images with a resolution of 0.9 x 0.9 x 3 mm(3) were successfully obtained using different interleaves ranging from 8-32. The measured apparent diffusion coefficient (ADC) in the homogenous gel phantom was (1.66 +/- 0.09) x 10(-3) mm(2)/second, which was in a good agreement with the reported literature values.Conclusion: The self-navigated multishot variable-density spiral acquisition provides a time efficient approach to acquire high resolution provides a time efficient approach to acquire high resolution diffusion-weighted images on a clinical scanner. The reconstruction algorithm based on motion correction in the k-space data is robust, and measured ADC values are accurate and reproducible.