From the Department of Radiology, University of Washington, 1959 NE Pacific St, Box 357115, Seattle, WA 98195 (O.K., N.B., G.M.C., D.V.S., A.M.); Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah (E.Y.A., H.A.); Department of Radiology, UT Southwestern Medical Center, Dallas, Tex (N.R., T.Y.); Department of MRI Development, Philips Healthcare, Best, the Netherlands (H.M.P.); Department of Radiology, New York University Langone Health-Long Island Division, New York, NY (J.W.R.).
Radiographics. 2024 Aug;44(8):e230173. doi: 10.1148/rg.230173.
T1-weighted (T1W) pulse sequences are an indispensable component of clinical protocols in abdominal MRI but usually require multiple breath holds (BHs) during the examination, which not all patients can sustain. Patient motion can affect the quality of T1W imaging so that key diagnostic information, such as intrinsic signal intensity and contrast enhancement image patterns, cannot be determined. Patient motion also has a negative impact on examination efficiency, as multiple acquisition attempts prolong the duration of the examination and often remain noncontributory. Techniques for mitigation of motion-related artifacts at T1W imaging include multiple arterial acquisitions within one BH; free breathing with respiratory gating or respiratory triggering; and radial imaging acquisition techniques, such as golden-angle radial k-space acquisition (stack-of-stars). While each of these techniques has inherent strengths and limitations, the selection of a specific motion-mitigation technique is based on several factors, including the clinical task under investigation, downstream technical ramifications, patient condition, and user preference. The authors review the technical principles of free-breathing motion mitigation techniques in abdominal MRI with T1W sequences, offer an overview of the established clinical applications, and outline the existing limitations of these techniques. In addition, practical guidance for abdominal MRI protocol strategies commonly encountered in clinical scenarios involving patients with limited BH abilities is rendered. Future prospects of free-breathing T1W imaging in abdominal MRI are also discussed. RSNA, 2024 See the invited commentary by Fraum and An in this issue.
T1 加权（T1W）脉冲序列是腹部 MRI 临床方案中不可或缺的组成部分，但在检查过程中通常需要多次屏气（BH），并非所有患者都能耐受。患者运动可能会影响 T1W 成像的质量，以至于无法确定关键的诊断信息，如固有信号强度和对比增强图像模式。患者运动也会对检查效率产生负面影响，因为多次采集尝试会延长检查时间，而且往往没有帮助。用于减轻 T1W 成像中与运动相关伪影的技术包括在一次 BH 内进行多次动脉采集；带呼吸门控或呼吸触发的自由呼吸；以及径向成像采集技术，如黄金角度径向 k 空间采集（星形堆栈）。虽然这些技术中的每一种都有其内在的优势和局限性，但特定的运动缓解技术的选择取决于多个因素，包括正在研究的临床任务、下游技术影响、患者状况和用户偏好。作者回顾了腹部 MRI 中 T1W 序列的自由呼吸运动缓解技术的技术原理，概述了已建立的临床应用，并概述了这些技术的现有局限性。此外，还提供了在涉及 BH 能力有限的患者的临床场景中常见的腹部 MRI 协议策略方面的实用指导。还讨论了腹部 MRI 中自由呼吸 T1W 成像的未来前景。RSNA，2024 请参阅本期 Fraum 和 An 的特邀评论。
