Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
The Dementia Research Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London, UK.
Magn Reson Med. 2022 Aug;88(2):787-801. doi: 10.1002/mrm.29253. Epub 2022 Apr 11.
High-resolution quantitative multi-parameter mapping shows promise for non-invasively characterizing human brain microstructure but is limited by physiological artifacts. We implemented corrections for rigid head movement and respiration-related B0-fluctuations and evaluated them in healthy volunteers and dementia patients.
Camera-based optical prospective motion correction (PMC) and FID navigator correction were implemented in a gradient and RF-spoiled multi-echo 3D gradient echo sequence for mapping proton density (PD), longitudinal relaxation rate (R1) and effective transverse relaxation rate (R2*). We studied their effectiveness separately and in concert in young volunteers and then evaluated the navigator correction (NAVcor) with PMC in a group of elderly volunteers and dementia patients. We used spatial homogeneity within white matter (WM) and gray matter (GM) and scan-rescan measures as quality metrics.
NAVcor and PMC reduced artifacts and improved the homogeneity and reproducibility of parameter maps. In elderly participants, NAVcor improved scan-rescan reproducibility of parameter maps (coefficient of variation decreased by 14.7% and 11.9% within WM and GM respectively). Spurious inhomogeneities within WM were reduced more in the elderly than in the young cohort (by 9% vs. 2%). PMC increased regional GM/WM contrast and was especially important in the elderly cohort, which moved twice as much as the young cohort. We did not find a significant interaction between the two corrections.
Navigator correction and PMC significantly improved the quality of PD, R1, and R2* maps, particularly in less compliant elderly volunteers and dementia patients.
高分辨率定量多参数图谱有望无创地对人脑微观结构进行特征描述，但受到生理伪影的限制。我们实施了针对刚性头部运动和与呼吸相关的 B0 波动的校正，并在健康志愿者和痴呆症患者中进行了评估。
基于摄像头的光学前瞻性运动校正（PMC）和 FID 导航器校正被应用于质子密度（PD）、纵向弛豫率（R1）和有效横向弛豫率（R2*）的梯度和 RF 扰动脉冲三维梯度回波序列中进行多回波采集。我们分别在年轻志愿者中研究了它们的效果，然后在一组老年志愿者和痴呆症患者中评估了导航器校正（NAVcor）与 PMC 的联合效果。我们使用白质（WM）和灰质（GM）内的空间均匀性以及扫描-重扫测量作为质量指标。
NAVcor 和 PMC 减少了伪影，提高了参数图的均匀性和可重复性。在老年参与者中，NAVcor 提高了参数图的扫描-重扫可重复性（WM 和 GM 内的变异系数分别降低了 14.7%和 11.9%）。WM 内的假不均匀性在老年组中比年轻组减少得更多（减少了 9%对 2%）。PMC 增加了局部 GM/WM 对比度，在老年组中尤其重要，老年组的移动幅度是年轻组的两倍。我们没有发现这两种校正之间存在显著的相互作用。
导航器校正和 PMC 显著提高了 PD、R1 和 R2*图谱的质量，特别是在顺应性较差的老年志愿者和痴呆症患者中。
