Partial volume correction in arterial spin labeling perfusion MRI: A method to disentangle anatomy from physiology or an analysis step too far?
Partial volume correction in arterial spin labeling perfusion MRI: A method to disentangle anatomy from physiology or an analysis step too far?
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DOI：
10.1016/j.neuroimage.2021.118236
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发表时间：
2021-06-08
期刊：
影响因子：
5.7
通讯作者：
Asllani, Iris
中科院分区：
文献类型：
--
作者：
Chappell, Michael A.;Kennedy McConnell, Flora A.;Asllani, Iris
动脉自旋标记（ASL）MRI灌注图像的空间分辨率与大脑中功能不同组织的解剖结构不匹配导致部分容积效应（PVE），这进而混淆了对特定感兴趣组织（如灰质或白色物质）灌注的估计。这种混淆的发生是因为图像体素包含具有不同灌注特性的组织的混合物，导致估计的灌注值主要反映体素中组织的体积比例，而不是该体积内任何特定感兴趣组织的灌注。已经认识到PVE影响脑灌注的研究，并且其影响在灌注变化与脑结构改变同时发生的研究中可能更加明显，例如涉及萎缩患者人群与对照受试者之间的比较的研究，或在广泛年龄范围内比较受试者的研究。然而，PVE校正（PVEc）的应用目前是有限的，所采用的方法仍然不一致。在这篇文章中，我们概述了在ASL测量灌注PVE的影响，解释了PVEC的主要原则，并提供了一个批评的最先进的使用这种方法的当前状态。此外，我们研究了目前使用的PVEC灌注研究，是否有证据支持其更广泛的采用。我们的结论是，有健全的理论动机使用PVEC与传统的，“未经纠正的”，图像，并鼓励这种组合的报告。PVEc的方法现在可以在标准的神经成像工具箱中使用，这使得我们的建议易于实施。然而，还有更多的工作要做，以建立PVEc的价值以及现有PVEc方法的有效性和鲁棒性。
The mismatch in the spatial resolution of Arterial Spin Labeling (ASL) MRI perfusion images and the anatomy of functionally distinct tissues in the brain leads to a partial volume effect (PVE), which in turn confounds the estimation of perfusion into a specific tissue of interest such as gray or white matter. This confound occurs because the image voxels contain a mixture of tissues with disparate perfusion properties, leading to estimated perfusion values that reflect primarily the volume proportions of tissues in the voxel rather than the perfusion of any particular tissue of interest within that volume. It is already recognized that PVE influences studies of brain perfusion, and that its effect might be even more evident in studies where changes in perfusion are co-incident with alterations in brain structure, such as studies involving a comparison between an atrophic patient population vs control subjects, or studies comparing subjects over a wide range of ages. However, the application of PVE correction (PVEc) is currently limited and the employed methodologies remain inconsistent. In this article, we outline the influence of PVE in ASL measurements of perfusion, explain the main principles of PVEc, and provide a critique of the current state of the art for the use of such methods. Furthermore, we examine the current use of PVEc in perfusion studies and whether there is evidence to support its wider adoption. We conclude that there is sound theoretical motivation for the use of PVEc alongside conventional, 'uncorrected', images, and encourage such combined reporting. Methods for PVEc are now available within standard neuroimaging toolboxes, which makes our recommendation straightforward to implement. However, there is still more work to be done to establish the value of PVEc as well as the efficacy and robustness of existing PVEc methods.