The feasibility of quantitative MRI of perivascular spaces at 7T.
The feasibility of quantitative MRI of perivascular spaces at 7T.
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DOI：
10.1016/j.jneumeth.2015.09.001
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发表时间：
2015-12-30
影响因子：
3
通讯作者：
Zhou XJ
中科院分区：
文献类型：
--
作者：
Cai K;Tain R;Das S;Damen FC;Sui Y;Valyi-Nagy T;Elliott MA;Zhou XJ
脑血管周围空间（PVS）扩张与许多疾病有关，包括衰老、痴呆和阿尔茨海默病（AD）。传统上，PVS评估主要基于在临床场强（≤ 3 T）下采集的MR图像中PVS数量、大小和形状的主观观察。本研究测试了使用MRI扫描仪对脑PVS进行成像和定量的可行性。在7 T全身MRI扫描仪上采集健康受试者（n=3）和AD患者（n=5）的3D高分辨率T2加权脑图像。为了自动分割小的高密度流体填充PVS结构，我们还开发了一个定量程序的基础上的算法的空间梯度，组件连接，边缘检测，k均值聚类等，产生定量结果的白色物质PVS体积密度。自动分割的PVS的3D图显示，与年龄匹配的健康对照相比，由于PVS扩张，AD患者的PVS密度明显增加（AD患者为8.0 ± 2.1 v/v%，对照为4.9 ± 1.3%，p<0.05）。我们证明，7 T可提供足够的SNR和分辨率，用于定量测量深度白色物质中的PVS，这对临床MRI系统（≤ 3 T）具有挑战性。与传统的视觉计数和评价PVS相比，我们开发的定量方法是自动和客观的。7 T下的定量PVS MRI可作为PVS扩张疾病的非侵入性和内源性成像生物标志物。
Dilated brain perivascular spaces (PVSs) are found to be associated with many conditions, including aging, dementia, and Alzheimer's disease (AD). Conventionally, PVS assessment is mainly based on subjective observations of the number, size and shape of PVSs in MR images collected at clinical field strengths (≤ 3T). This study tests the feasibility of imaging and quantifying brain PVS with an ultrahigh 7T whole-body MRI scanner. 3D high resolution T2-weighted brain images from healthy subjects (n=3) and AD patients (n=5) were acquired on a 7T whole-body MRI scanner. To automatically segment the small hyperintensive fluid-filling PVS structures, we also developed a quantitative program based on algorithms for spatial gradient, component connectivity, edge-detection, k-means clustering, etc, producing quantitative results of white matter PVS volume densities. The 3D maps of automatically segmented PVS show an apparent increase in PVS density in AD patients compared to age-matched healthy controls due to the PVS dilation (8.0 ± 2.1 v/v% in AD vs. 4.9 ± 1.3% in controls, p<0.05). We demonstrated that 7T provides sufficient SNR and resolution for quantitatively measuring PVSs in deep white matter that is challenging with clinical MRI systems (≤ 3T). Compared to the conventional visual counting and rating for the PVS assessment, the quantitation method we developed is automatic and objective. Quantitative PVS MRI at 7T may serve as a non-invasive and endogenous imaging biomarker for diseases with PVS dilation.