标题： 多shot双极性GRAPPA：多shot EPI的鲁棒尼奎斯特鬼影校正 显示英文标题

标题： Multishot Dual Polarity GRAPPA: Robust Nyquist Ghost Correction for multishot EPI

摘要： 目的：本研究旨在开发一种针对多段回波平面成像（EPI）的鲁棒尼奎斯特鬼影校正方法。该方法有助于校正具有挑战性的尼奎斯特鬼影，特别是在高性能梯度或超高场扫描仪上。 方法：通过将DPG概念扩展到多段读出，开发了一种用于多段EPI鬼影校正的方法，称为多段双极性GRAPPA（msDPG）。msDPG采用定制的DPG内核来解决两种EPI读出极性之间的高阶相位差异，这些差异无法通过线性相位校正（LPC）完全解决。可以轻松地将高级正则化器与提出的msDPG结合使用，以在重建过程中校正生理学上的段间相位变化。此外，提出了一种校准优化方法，以提高DPG校准数据的质量并增强重建性能。 结果：在高性能梯度和超高场扫描仪上的体模和体内实验表明，msDPG的鬼影校正性能优于LPC，将鬼影与信号比（GSR）降低了50%以上。与传统DPG相比，msDPG提供的图像噪声放大更低，尤其是在平面内加速较大的采集中。因此，使用正则化重建，通过msDPG获得了高质量的亚毫米扩散图像。 结论：所提出的msDPG为多段EPI提供了一种鲁棒的尼奎斯特鬼影校正方法，实现了改进保真度的亚毫米成像。 显示英文摘要

摘要： Purpose: This work aims to develop a robust Nyquist ghost correction method for multishot echo-planar imaging (EPI). The method helps correct challenging Nyquist ghosts, particularly on scanners with high-performance gradients or ultra-high fields. Methods: A method for multishot EPI ghost correction, called multishot dual-polarity GRAPPA (msDPG), is developed by extending the DPG concept to multishot readouts. msDPG employs tailored DPG kernels to address high-order phase differences between two EPI readout polarities, which cannot be fully addressed using linear phase correction (LPC). Advanced regularizers can be readily employed with the proposed msDPG for physiologic inter-shot phase variation correction during reconstruction. Additionally, a calibration refinement method is proposed to improve the quality of the DPG calibration data and enhance reconstruction performance. Results: Phantom and in vivo experiments on scanners with high-performance gradients and ultra-high fields demonstrated that msDPG achieved superior ghost correction performance than LPC, reducing the ghost-to-signal ratio (GSR) by over 50%. Compared to conventional DPG, msDPG provided images with lower noise amplification, particularly for acquisitions with large in-plane acceleration. Consequently, high-fidelity, submillimeter diffusion images were obtained using msDPG with regularized reconstruction. Conclusion: The proposed msDPG provides a robust Nyquist ghost correction method for multishot EPI, enabling submillimeter imaging with improved fidelity.