The effect of hypointense white matter lesions on automated gray matter segmentation in multiple sclerosis.
The effect of hypointense white matter lesions on automated gray matter segmentation in multiple sclerosis.
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DOI：
10.1002/hbm.21402
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发表时间：
2012-12
影响因子：
4.8
通讯作者：
Palace J
中科院分区：
文献类型：
--
作者：
Gelineau-Morel R;Tomassini V;Jenkinson M;Johansen-Berg H;Matthews PM;Palace J
先前评估白色物质（WM）损伤和物质（GM）萎缩之间关系的成像研究已经引起了这样的关注，即多发性硬化（MS）WM病变可能通过在基于强度的组织分割期间诱导体素错误分类而影响GM体积的测量。在这里，我们使用病变填充方法量化了模拟和真实的MS大脑中的错误分类错误。使用这种方法，我们还纠正了GM的措施，然后将其与对照组进行比较，以评估这种病变引起的错误分类错误在临床研究中的影响。我们发现，较高的WM病变体积人为地减少了总GM体积。在患者中，这种效果约为模拟预测的72%。错误分类的体素位于GM/WM边界，可能远离病变。个体深灰质（DGM）结构的体积通常随着病变体积的增加而减少，与总GM的结果一致。在保留患者和对照组之间GM体积差异的同时，病变填充校正揭示了患者中更多的偏侧DGM形状变化，这在原始图像中并不明显。我们的研究结果证实，WM病变可以影响MRI测量的GM体积和形状在MS患者通过其对强度为基础的GM分割的影响。损伤程度越高，病变的影响越大，这支持使用病变填充来纠正这一问题，并提高结果的可解释性。体积或形态测量成像研究，其中病变量和特征可能在患者组之间变化或随时间变化，可能特别受益于这种校正。
Previous imaging studies assessing the relationship between white matter (WM) damage and matter (GM) atrophy have raised the concern that Multiple Sclerosis (MS) WM lesions may affect measures of GM volume by inducing voxel misclassification during intensity-based tissue segmentation. Here, we quantified this misclassification error in simulated and real MS brains using a lesion-filling method. Using this method, we also corrected GM measures in patients before comparing them with controls in order to assess the impact of this lesion-induced misclassification error in clinical studies. We found that higher WM lesion volumes artificially reduced total GM volumes. In patients, this effect was about 72% of that predicted by simulation. Misclassified voxels were located at the GM/WM border and could be distant from lesions. Volume of individual deep gray matter (DGM) structures generally decreased with higher lesion volumes, consistent with results from total GM. While preserving differences in GM volumes between patients and controls, lesion-filling correction revealed more lateralised DGM shape changes in patients, which were not evident with the original images. Our results confirm that WM lesions can influence MRI measures of GM volume and shape in MS patients through their effect on intensity-based GM segmentation. The greater effect of lesions at increasing levels of damage supports the use of lesion-filling to correct for this problem and improve the interpretability of the results. Volumetric or morphometric imaging studies, where lesion amount and characteristics may vary between groups of patients or change over time, may especially benefit from this correction.