Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada.
Division of Neurology, University of Alberta, Edmonton, AB, Canada.
J Magn Reson Imaging. 2017 Nov;46(5):1464-1473. doi: 10.1002/jmri.25682. Epub 2017 Mar 16.
To create an automated framework for localized analysis of deep gray matter (DGM) iron accumulation and demyelination using sparse classification by combining quantitative susceptibility (QS) and transverse relaxation rate (R2*) maps, for evaluation of DGM in multiple sclerosis (MS) phenotypes relative to healthy controls.
R2*/QS maps were computed using a 4.7T 10-echo gradient echo acquisition from 16 clinically isolated syndrome (CIS), 41 relapsing-remitting (RR), 40 secondary-progressive (SP), 13 primary-progressive (PP) MS patients, and 75 controls. Sparse classification for R2*/QS maps of segmented caudate nucleus (CN), putamen (PU), thalamus (TH), and globus pallidus (GP) structures produced localized maps of iron/myelin in MS patients relative to controls. Paired t-tests, with age as a covariate, were used to test for statistical significance (P ≤ 0.05).
In addition to DGM structures found significantly different in patients compared to controls using whole region analysis, singular sparse analysis found significant results in RRMS PU R2* (P = 0.03), TH R2* (P = 0.04), CN QS (P = 0.04); in SPMS CN R2* (P = 0.04), GP R2* (P = 0.05); and in PPMS CN R2* (P = 0.04), TH QS (P = 0.04). All sparse regions were found to conform to an iron accumulation pattern of changes in R2*/QS, while none conformed to demyelination. Intersection of sparse R2*/QS regions also resulted in RRMS CN R2* becoming significant, while RRMS R2* TH and PPMS QS TH becoming insignificant. Common iron-associated volumes in MS patients and their effect size progressively increased with advanced phenotypes.
A localized technique for identifying sparse regions indicative of iron or myelin in the DGM was developed. Progressive iron accumulation with advanced MS phenotypes was demonstrated, as indicated by iron-associated sparsity and effect size.
1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1464-1473.
创建一个自动化框架，用于使用稀疏分类结合定量磁化率（QS）和横向弛豫率（R2*）图对深部灰质（DGM）铁积累和脱髓鞘进行局部分析，以评估多发性硬化症（MS）表型相对于健康对照的 DGM。
使用 4.7T 10 回波梯度回波采集从 16 例临床孤立综合征（CIS）、41 例复发缓解型（RR）、40 例继发进展型（SP）、13 例原发进展型（PP）MS 患者和 75 例对照中计算 R2*/QS 图。对分割尾状核（CN）、壳核（PU）、丘脑（TH）和苍白球（GP）结构的 R2*/QS 图进行稀疏分类，生成 MS 患者相对于对照的铁/髓鞘的局部图谱。使用配对 t 检验，以年龄为协变量，检验统计学意义（P ≤ 0.05）。
除了使用全区域分析发现 DGM 结构在患者中与对照组明显不同外，单一稀疏分析还发现 RRMS PU R2*（P = 0.03）、TH R2*（P = 0.04）、CN QS（P = 0.04）差异有统计学意义；SPMS CN R2*（P = 0.04）、GP R2*（P = 0.05）；PPMS CN R2*（P = 0.04）、TH QS（P = 0.04）。所有稀疏区域都发现符合 R2*/QS 变化的铁积累模式，而没有一个符合脱髓鞘模式。稀疏 R2*/QS 区域的交集也导致 RRMS CN R2变得显著，而 RRMS R2TH 和 PPMS QS TH 变得不显著。随着疾病表型的进展，MS 患者的共同铁相关体积及其效应量逐渐增加。
开发了一种用于识别深部灰质（DGM）中稀疏区域的局部技术，这些稀疏区域提示存在铁或髓鞘。随着 MS 表型的进展，铁的积累逐渐增加，这与铁相关的稀疏性和效应量一致。
1 技术功效：第 1 阶段 J. Magn. Reson. Imaging 2017;46:1464-1473.
