Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
Department of Physics & Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
Magn Reson Med. 2023 Jan;89(1):192-204. doi: 10.1002/mrm.29438. Epub 2022 Sep 12.
Many MRI sequences are sensitive to motion and its associated artifacts. The linearized geometric solution (LGS), a balanced steady-state free precession (bSSFP) off-resonance signal demodulation technique, is evaluated with respect to motion artifact resilience.
The mechanism and extent of LGS motion artifact resilience is examined in simulated, flow phantom, and in vivo clinical imaging. Motion artifact correction capabilities are decoupled from susceptibility artifact correction when feasible to permit controlled analysis of motion artifact correction when comparing the LGS with standard and phase-cycle-averaged (complex sum) bSSFP imaging.
Simulations reveal that the LGS demonstrates motion artifact reduction capabilities similar to standard clinical bSSFP imaging techniques, with slightly greater resilience in high SNR regions and for shorter-duration motion. Flow phantom experiments assert that the LGS reduces shorter-duration motion artifact error by ∼24%-65% relative to the complex sum, whereas reconstructions exhibit similar error reduction for constant motion. In vivo analysis demonstrates that in the internal auditory canal/orbits, the LGS was deemed to have less artifact in 24%/49% and similar artifact in 76%/51% of radiological assessments relative to the complex sum, and the LGS had less artifact in 97%/81% and similar artifact in 3%/16% of assessments relative to standard bSSFP. Only 2 of 63 assessments deemed the LGS inferior to either complex sum or standard bSSFP in terms of artifact reduction.
The LGS provides sufficient bSSFP motion artifact resilience to permit robust elimination of susceptibility artifacts, inspiring its use in a wide variety of applications.
许多 MRI 序列对运动及其相关伪影敏感。线性化几何解（LGS）是一种平衡稳态自由进动（bSSFP）去谐信号解调技术，本文评估了其对运动伪影的弹性。
在模拟、流动体模和体内临床成像中检查了 LGS 运动伪影弹性的机制和程度。当可行时，将运动伪影校正能力与磁化率伪影校正能力解耦，以允许在将 LGS 与标准和相位周期平均（复数和）bSSFP 成像进行比较时，对运动伪影校正进行受控分析。
模拟表明，LGS 表现出与标准临床 bSSFP 成像技术相似的运动伪影减少能力，在高 SNR 区域和短持续时间运动中具有稍大的弹性。流动体模实验表明，LGS 可将短持续时间运动伪影错误相对于复数和减少约 24％-65％，而重建则表现出相似的恒定运动错误减少。体内分析表明，在内耳道/眼眶中，LGS 在 24％/49％的放射学评估中被认为具有较少的伪影，在 76％/51％的评估中具有相似的伪影，相对于复数和，LGS 在 97％/81％的评估中具有较少的伪影，在 3％/16％的评估中具有相似的伪影。在 63 项评估中，只有 2 项评估认为 LGS 在减少伪影方面劣于复数和或标准 bSSFP。
LGS 提供了足够的 bSSFP 运动伪影弹性，以允许对磁化率伪影进行稳健消除，激发了其在各种应用中的使用。
