Papp Daniel, Callaghan Martina F, Meyer Heiko, Buckley Craig, Weiskopf Nikolaus
Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom.
SIEMENS Healthcare GmbH, Erlanger, Germany.
Magn Reson Med. 2016 Nov;76(5):1478-1485. doi: 10.1002/mrm.26058. Epub 2015 Nov 26.
Inter-scan motion causes differential receive field modulation between scans, leading to errors when they are combined to quantify MRI parameters. We present a robust and efficient method that accounts for inter-scan motion by removing this modulation before parameter quantification.
Five participants moved between two high-resolution structural scans acquired with different flip angles. Before each high-resolution scan, the effective relative sensitivity of the receive head coil was estimated by combining two rapid low-resolution scans acquired receiving on each of the body and head coils. All data were co-registered and sensitivity variations were removed from the high-resolution scans by division with the effective relative sensitivity. R1 maps with and without this correction were calculated and compared against reference maps unaffected by inter-scan motion.
Even after coregistration, inter-scan motion significantly biased the R1 maps, leading to spurious variation in R1 in brain tissue and deviations with respect to a no-motion reference. The proposed correction scheme reduced the error to within the typical scan-rescan error observed in datasets unaffected by motion.
Inter-scan motion negatively impacts the accuracy and precision of R1 mapping. We present a validated correction method that accounts for position-specific receive field modulation. Magn Reson Med 76:1478-1485, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
扫描间运动导致扫描间接收场调制不同，在组合扫描以量化MRI参数时会产生误差。我们提出一种稳健且高效的方法，通过在参数量化之前消除这种调制来考虑扫描间运动。
五名参与者在两次以不同翻转角采集的高分辨率结构扫描之间移动。在每次高分辨率扫描之前，通过组合在身体和头部线圈上采集的两次快速低分辨率扫描来估计接收头线圈的有效相对灵敏度。所有数据进行配准，并通过除以有效相对灵敏度从高分辨率扫描中去除灵敏度变化。计算有无这种校正的R1图，并与不受扫描间运动影响的参考图进行比较。
即使在配准之后，扫描间运动仍会显著使R1图产生偏差，导致脑组织中R1出现虚假变化以及与无运动参考值的偏差。所提出的校正方案将误差降低到在不受运动影响的数据集中观察到的典型重扫误差范围内。
扫描间运动对R1映射的准确性和精确性有负面影响。我们提出一种经过验证的校正方法，该方法考虑了特定位置的接收场调制。《磁共振医学》76:1478 - 1485, 2016。© 2015作者。《磁共振医学》由威利期刊公司代表国际磁共振医学学会出版。这是一篇根据知识共享署名许可协议条款的开放获取文章，允许在任何媒介中使用、分发和复制，前提是正确引用原始作品。
