The use of a generalized reconstruction by inversion of coupled systems (GRICS) approach for generic respiratory motion correction in PET/MR imaging
The use of a generalized reconstruction by inversion of coupled systems (GRICS) approach for generic respiratory motion correction in PET/MR imaging
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DOI：
10.1088/0031-9155/60/6/2529
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发表时间：
2015-03-21
影响因子：
3.5
通讯作者：
Visvikis, Dimitris
中科院分区：
文献类型：
--
作者：
Fayad, Hadi;Odille, Freddy;Visvikis, Dimitris
呼吸运动是PET/MR等多模态成像中伪影的来源。解决方案包括回顾性或前瞻性门控。然而，它们在临床实践中的使用有限，因为它们增加了整体采集持续时间以保持整体图像质量。更精细的方法包括使用4D MR数据集来提取空间变形，以便校正PET中的呼吸运动。这种方法的主要缺点是与4D MR成像相关联的相对长的采集时间，这通常与临床PET/MR协议不兼容。这项工作的目的是克服这些限制，利用广义重建反演耦合系统（GRICS）的方法。该方法基于MR图像重建过程中的运动联合估计，提供内部结构运动和相关变形矩阵，用于PET呼吸运动校正中的回顾性使用。通过将GRICS生成的MR图像与通过回顾性门控获得的4D MR系列进行比较，首先在4名MR志愿者和2名PET/MR患者数据集上对该方法进行了验证。在第二步中，使用GATE Monte Carlo模拟平台模拟与采集的4D MR图像相对应的4D PET数据集。GRICS生成的变形矩阵随后用于校正呼吸运动，与基于模拟和两个4D PET/MR患者数据集的4D MR图像的变形进行比较。结果证实，GRICS同步MR图像与采集的4D MR系列相关性良好。类似地，考虑到PET模拟肿瘤以及PET真实的肿瘤，使用GRICS进行呼吸运动校正允许对病变对比度、位置和大小的等同百分比改进。这项工作证明了在组合PET/MR中使用GRICS进行PET呼吸运动校正的潜在利益，使用较短的持续时间采集，而不需要4D MRI和相关的特定MR序列。
Respiratory motion is a source of artifacts in multimodality imaging such as PET/MR. Solutions include retrospective or prospective gating. They have however found limited use in clinical practice, since their increased overall acquisition duration to maintain overall image quality. More elaborate methods consist of using 4D MR datasets to extract spatial deformations in order to correct for the respiratory motion in PET. The main drawbacks of such approaches is the relatively long acquisition times associated with 4D MR imaging which is often incompatible with clinical PET/MR protocols. The objective of this work was to overcome these limitations by exploiting a generalized reconstruction by inversion of coupled systems (GRICS) approach. The methodology is based on a joint estimation of motion during the MR image reconstruction process, providing internal structure motion and associated deformation matrices for retrospective use in PET respiratory motion correction. This method was first validated on four MR volunteers and two PET/MR patient datasets by comparing GRICS generated MR images to 4D MR series obtained by retrospective gating. In a second step 4D PET datasets corresponding to acquired 4D MR images were simulated using the GATE Monte Carlo simulation platform. GRICS generated deformation matrices were subsequently used to correct respiratory motion in comparison to the 4D MR image based deformations both for the simulated and the two 4D PET/MR patient datasets. Results confirm that GRICS synchronized MR images correlate well with the acquired 4D MR series. Similarly, the use of GRICS for respiratory motion correction allows an equivalent percentage improvement on lesion contrast, position and size, considering the PET simulated tumors as well as PET real tumors. This work demonstrates the potential interest of using GRICS for PET respiratory motion correction in combined PET/MR using shorter duration acquisitions without the need for 4D MRI and associated specific MR sequences.