Fujiwara E, Kmech J A, Cobzas D, Sun H, Seres P, Blevins G, Wilman A H
From the Departments of Psychiatry (E.F., J.A.K.).
Computer Science (D.C.).
AJNR Am J Neuroradiol. 2017 May;38(5):942-948. doi: 10.3174/ajnr.A5109. Epub 2017 Feb 23.
Deep gray matter iron accumulation is increasingly recognized in association with multiple sclerosis and can be measured in vivo with MR imaging. The cognitive implications of this pathology are not well-understood, especially vis-à-vis deep gray matter atrophy. Our aim was to investigate the relationships between cognition and deep gray matter iron in MS by using 2 MR imaging-based iron-susceptibility measures.
Forty patients with multiple sclerosis (relapsing-remitting, = 16; progressive, = 24) and 27 healthy controls were imaged at 4.7T by using the transverse relaxation rate and quantitative susceptibility mapping. The transverse relaxation rate and quantitative susceptibility mapping values and volumes (atrophy) of the caudate, putamen, globus pallidus, and thalamus were determined by multiatlas segmentation. Cognition was assessed with the Brief Repeatable Battery of Neuropsychological Tests. Relationships between cognition and deep gray matter iron were examined by hierarchic regressions.
Compared with controls, patients showed reduced memory ( < .001) and processing speed ( = .02) and smaller putamen ( < .001), globus pallidus ( = .002), and thalamic volumes ( < .001). Quantitative susceptibility mapping values were increased in patients compared with controls in the putamen ( = .003) and globus pallidus ( = .003). In patients only, thalamus ( < .001) and putamen ( = .04) volumes were related to cognitive performance. After we controlled for volume effects, quantitative susceptibility mapping values in the globus pallidus ( = .03; trend for transverse relaxation rate, = .10) were still related to cognition.
Quantitative susceptibility mapping was more sensitive compared with the transverse relaxation rate in detecting deep gray matter iron accumulation in the current multiple sclerosis cohort. Atrophy and iron accumulation in deep gray matter both have negative but separable relationships to cognition in multiple sclerosis.
深部灰质铁沉积与多发性硬化的相关性日益受到认可，且可通过磁共振成像（MR）在体测量。这种病理改变对认知的影响尚未完全明确，尤其是相对于深部灰质萎缩而言。我们的目的是通过两种基于MR成像的铁敏感性测量方法，研究多发性硬化患者认知与深部灰质铁之间的关系。
40例多发性硬化患者（复发缓解型，16例；进展型，24例）和27名健康对照者接受了4.7T磁共振成像，采用横向弛豫率和定量磁化率成像。通过多图谱分割确定尾状核、壳核、苍白球和丘脑的横向弛豫率、定量磁化率成像值及体积（萎缩情况）。使用简易可重复神经心理测验电池评估认知功能。通过分层回归分析认知与深部灰质铁之间的关系。
与对照组相比，患者的记忆功能（P<0.001）和处理速度（P=0.02）降低，壳核（P<0.001）、苍白球（P=0.002）和丘脑体积（P<0.001）减小。与对照组相比，患者壳核（P=0.003）和苍白球（P=0.003）的定量磁化率成像值升高。仅在患者中，丘脑体积（P<0.001）和壳核体积（P=0.04）与认知表现相关。在控制体积效应后，苍白球的定量磁化率成像值（P=0.03；横向弛豫率呈趋势性，P=0.10）仍与认知相关。
在当前多发性硬化队列中，定量磁化率成像在检测深部灰质铁沉积方面比横向弛豫率更敏感。深部灰质萎缩和铁沉积在多发性硬化中均与认知呈负相关，但二者关系可区分。
