Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, USA.
Magn Reson Med. 2021 Feb;85(2):855-867. doi: 10.1002/mrm.28475. Epub 2020 Aug 27.
Respiratory motion in cardiovascular MRI presents a challenging problem with many potential solutions. Current approaches require breath-holds, apply retrospective image registration, or significantly increase scan time by respiratory gating. Myocardial T and T mapping techniques are particularly sensitive to motion as they require multiple source images to be accurately aligned prior to the estimation of tissue relaxation. We propose a patient-specific prospective motion correction (PROCO) strategy that corrects respiratory motion on the fly with the goal of reducing the spatial variation of myocardial parametric mapping techniques.
A rapid, patient-specific training scan was performed to characterize respiration-induced motion of the heart relative to a diaphragmatic navigator, and a parametric mapping pulse sequence utilized the resulting motion model to prospectively update the scan plane in real-time. Midventricular short-axis T and T maps were acquired under breath-hold or free-breathing conditions with and without PROCO in 7 healthy volunteers and 3 patients. T and T were measured in 6 segments and compared to reference standard breath-hold measurements using Bland-Altman analysis.
PROCO significantly reduced the spatial variation of parametric maps acquired during free-breathing, producing limits of agreement of -47.16 to 30.98 ms (T ) and -1.35 to 4.02 ms (T ), compared to -67.77 to 74.34 ms (T ) and -2.21 to 5.62 ms (T ) for free-breathing acquisition without PROCO.
Patient-specific respiratory PROCO method significantly reduced the spatial variation of myocardial T and T mapping, while allowing for 100% efficient free-breathing acquisitions.
心血管 MRI 中的呼吸运动是一个具有挑战性的问题，有许多潜在的解决方案。目前的方法需要屏气、应用回顾性图像配准，或通过呼吸门控显著增加扫描时间。心肌 T1 和 T2 映射技术对运动特别敏感，因为它们需要多个源图像在准确对齐后才能准确估计组织弛豫。我们提出了一种基于患者的前瞻性运动校正（PROCO）策略，该策略可实时校正呼吸运动，目标是减少心肌参数映射技术的空间变异性。
进行了快速的基于患者的训练扫描，以表征心脏相对于膈肌导航器的呼吸诱导运动，并利用所得的运动模型来前瞻性地实时更新扫描平面。在 7 名健康志愿者和 3 名患者中，在屏气或自由呼吸条件下，使用和不使用 PROCO 采集心尖短轴中部 T1 和 T2 图。在 6 个节段测量 T1 和 T2，并使用 Bland-Altman 分析与参考标准屏气测量进行比较。
PROCO 显著降低了自由呼吸采集时参数图的空间变异性，产生的一致性界限为-47.16 至 30.98 ms（T1）和-1.35 至 4.02 ms（T2），而自由呼吸采集时无 PROCO 的一致性界限为-67.77 至 74.34 ms（T1）和-2.21 至 5.62 ms（T2）。
基于患者的呼吸 PROCO 方法显著降低了心肌 T1 和 T2 映射的空间变异性，同时允许 100%有效的自由呼吸采集。
