Bonnier Guillaume, Maréchal Benedicte, Fartaria Mário João, Falkowskiy Pavel, Marques José P, Simioni Samanta, Schluep Myriam, Du Pasquier Renaud, Thiran Jean-Philippe, Krueger Gunnar, Granziera Cristina
A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.
Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare, Lausanne, Switzerland.
Front Neurol. 2017 Sep 27;8:506. doi: 10.3389/fneur.2017.00506. eCollection 2017.
Quantitative and semi-quantitative MRI (qMRI) metrics provide complementary specificity and differential sensitivity to pathological brain changes compatible with brain inflammation, degeneration, and repair. Moreover, advanced magnetic resonance imaging (MRI) metrics with overlapping elements amplify the true tissue-related information and limit measurement noise. In this work, we combined multiple advanced MRI parameters to assess focal and diffuse brain changes over 2 years in a group of early-stage relapsing-remitting MS patients.
Thirty relapsing-remitting MS patients with less than 5 years disease duration and nine healthy subjects underwent 3T MRI at baseline and after 2 years including T1, T2, T2* relaxometry, and magnetization transfer imaging. To assess longitudinal changes in normal-appearing (NA) tissue and lesions, we used analyses of variance and Bonferroni correction for multiple comparisons. Multivariate linear regression was used to assess the correlation between clinical outcome and multiparametric MRI changes in lesions and NA tissue.
In patients, we measured a significant longitudinal decrease of mean T2 relaxation times in NA white matter ( = 0.005) and a decrease of T1 relaxation times in the pallidum ( < 0.05), which are compatible with edema reabsorption and/or iron deposition. No longitudinal changes in qMRI metrics were observed in controls. In MS lesions, we measured a decrease in T1 relaxation time (-value < 2.2e-16) and a significant increase in MTR (-value < 1e-6), suggesting repair mechanisms, such as remyelination, increased axonal density, and/or a gliosis. Last, the evolution of advanced MRI metrics-and not changes in lesions or brain volume-were correlated to motor and cognitive tests scores evolution (Adj- > 0.4, < 0.05). In summary, the combination of multiple advanced MRI provided evidence of changes compatible with focal and diffuse brain repair at early MS stages as suggested by histopathological studies.
定量和半定量磁共振成像（qMRI）指标为与脑炎症、退变及修复相关的病理性脑改变提供了互补的特异性和鉴别敏感性。此外，具有重叠元素的先进磁共振成像（MRI）指标可放大真实的组织相关信息并限制测量噪声。在本研究中，我们结合多个先进的MRI参数，对一组早期复发缓解型多发性硬化（MS）患者在2年时间内的局灶性和弥漫性脑改变进行评估。
30例病程小于5年的复发缓解型MS患者和9名健康受试者在基线及2年后接受了3T MRI检查，包括T1、T2、T2*弛豫测量及磁化传递成像。为评估正常表现（NA）组织和病灶的纵向变化，我们采用方差分析及Bonferroni校正进行多重比较。采用多元线性回归评估临床结局与病灶及NA组织多参数MRI变化之间的相关性。
在患者中，我们测得NA白质的平均T2弛豫时间有显著的纵向缩短（P = 0.005），苍白球的T1弛豫时间缩短（P < 0.05），这与水肿吸收和/或铁沉积相符。在对照组中未观察到qMRI指标的纵向变化。在MS病灶中，我们测得T1弛豫时间缩短（P值< 2.2e - 16），磁化传递比（MTR）显著增加（P值< 1e - 6），提示存在修复机制，如髓鞘再生、轴突密度增加和/或胶质增生。最后，先进MRI指标的演变——而非病灶或脑容量的变化——与运动和认知测试分数的演变相关（校正R² > 0.4，P < 0.05）。总之，正如组织病理学研究所提示的，多个先进MRI指标的联合使用为MS早期局灶性和弥漫性脑修复相关的变化提供了证据。
