Borisch Eric A, Grimm Roger C, Kargar Soudabeh, Kawashima Akira, Rossman Phillip J, Riederer Stephen J
Department of Radiology, Mayo Clinic, Rochester, MN, USA.
Department of Radiology, University of Wisconsin, Madison, WI, USA.
Magn Reson Med. 2021 Mar;85(3):1350-1363. doi: 10.1002/mrm.28518. Epub 2020 Sep 24.
The purpose is to develop a retrospective correction for subtle slice-to-slice positional inconsistencies that can occur when overlapped slices are acquired for super resolution in T -weighted spin-echo multislice imaging.
Spin-echo acquisition of overlapped slices is typically done using multiple passes. After the passes are assembled into the final slice set, consecutive slices are correlated due to their overlap. Cross correlation was used to measure slice-to-slice displacement. After Z-dependent filtering to preserve true object shape, the displacements were used to correct slice position. The method was tested in a phantom moved slowly (0.16-0.63 mm/pass) under computer control and in vivo in 16 patients having prostate MRI.
Over the motion range, the correlation method had an accuracy within 0.03 mm/pass and precision ± 0.20 mm (ie, subpixel). Corrected images visually resemble the true object. Over the patient studies, the mean range of motion in the anterior-posterior direction was 1.63 mm. Motion-corrected axial images and the sagittal reformats were evaluated as significantly superior over those formed without motion correction.
The retrospective correlation-based motion-correction method provides significant improvement in the slice-to-slice registration necessary for effective super resolution using overlapped slices.
开发一种回顾性校正方法，用于校正T加权自旋回波多层成像中为实现超分辨率而采集重叠切片时可能出现的细微片间位置不一致。
重叠切片的自旋回波采集通常通过多次采集来完成。在将多次采集组合成最终切片集后，连续切片由于重叠而具有相关性。互相关用于测量片间位移。在进行与Z相关的滤波以保留真实物体形状后，利用这些位移来校正切片位置。该方法在计算机控制下缓慢移动（0.16 - 0.63毫米/次）的模型中以及在16例进行前列腺MRI检查的患者体内进行了测试。
在运动范围内，相关方法的精度在0.03毫米/次以内，精密度为±0.20毫米（即亚像素级）。校正后的图像在视觉上类似于真实物体。在患者研究中，前后方向的平均运动范围为1.63毫米。经运动校正的轴向图像和矢状面重组图像被评估为明显优于未进行运动校正所形成的图像。
基于回顾性相关的运动校正方法在使用重叠切片进行有效超分辨率所需的片间配准方面有显著改进。
