Lee D, Pollock S, Keall P, Kim T
The unversity of Sydney, Camperdown, NSW.
Med Phys. 2012 Jun;39(6Part28):3975. doi: 10.1118/1.4736222.
It is aim to test the hypothesis that a dynamic keyhole MRI reconstruction technique using external/internal respiratory surrogate position reduces acquisition time while retaining image quality for real-time tumor monitoring, compared to the conventional keyhole technique.
46 thoracic MRI studies with 13 healthy human subjects have been acquired using a 3T GE MRI. Acquired MR images were reconstructed using zero-filling, conventional keyhole and the proposed respiratory motion based dynamic keyhole techniques; resultant images were then compared for image quality. Undersampled k-space rate in the phase encoding direction was determined based on the difference between the original image and the reconstructed image. The position of abdominal muscles and diaphragm were used to determine any excess data that exists in the overlaid temporal data. In addition, the feasibility of the dynamic keyhole method was applied using lung tumor MR images.
The result from dynamic keyhole using respiratory motion demonstrated significant improvement compared with the zero-filling and conventional keyhole methods. Firstly, the dynamic keyhole method using external respiratory motion had an overlaid average of 79.7% (204 lines) of 256 lines from 46 datasets, compared to 63.9% in zero-filling and 74.3% in conventional keyhole. Secondly, dynamic keyhole method using internal diaphragm motion had an overlaid average of 84.5% (216 lines) of 256 lines from all datasets compared to 67.1% and 77.8% or zero-filling and conventional keyhole, respectively. Lastly, dynamic keyhole has been validated with one dataset involving lung tumor MR images. Image blurring artifacts and inferior resolution were not present in the final MR images using dynamic keyhole.
Dynamic keyhole method using respiratory external/internal surrogate motion has been proposed to reconstruct MR images without image artifacts and with superior resolution. This method is applicable to MR images targeting lungs and other organs affected by respiratory motion for real-time tumor motion monitoring.
旨在验证以下假设：与传统锁孔技术相比，使用外部/内部呼吸替代位置的动态锁孔MRI重建技术在保留图像质量以进行实时肿瘤监测的同时，可减少采集时间。
使用3T GE MRI对13名健康人类受试者进行了46项胸部MRI研究。采集的MR图像使用零填充、传统锁孔技术和基于呼吸运动的动态锁孔技术进行重建；然后比较所得图像的质量。基于原始图像和重建图像之间的差异，确定相位编码方向上的欠采样k空间率。使用腹部肌肉和膈肌的位置来确定叠加的时间数据中存在的任何多余数据。此外，使用肺部肿瘤MR图像应用动态锁孔方法的可行性。
与零填充和传统锁孔方法相比，使用呼吸运动的动态锁孔结果显示出显著改善。首先，使用外部呼吸运动的动态锁孔方法在46个数据集中叠加了256条线中的79.7%（204条线），相比之下，零填充为63.9%，传统锁孔为74.3%。其次，使用内部膈肌运动的动态锁孔方法在所有数据集中叠加了256条线中的84.5%（216条线），相比之下，零填充和传统锁孔分别为67.1%和77.8%。最后，动态锁孔已在一个涉及肺部肿瘤MR图像的数据集上得到验证。使用动态锁孔的最终MR图像中不存在图像模糊伪影和分辨率低下的情况。
已提出使用呼吸外部/内部替代运动的动态锁孔方法来重建无图像伪影且具有高分辨率的MR图像。该方法适用于针对肺部和其他受呼吸运动影响的器官的MR图像，用于实时肿瘤运动监测。
