METHODS: This is a prospective, observational, longitudinal study including 25 DM1 patients that performed at least two muscle MRIs. Demographic and genetic characteristics were recorded. Muscular Impairment Rating Scale (MIRS) and MRC score were performed within 3 months from MRIs at baseline (BL) and at follow-up (FU). We analysed 32 muscles of lower body (LB) and 17 muscles of upper body (UB) by T1 and STIR sequences. T1-, STIR- and atrophy scores and their variations were evaluated. Correlations between MRIs\' scores and demographic, clinical and genetic characteristics were analysed.
RESULTS: Eighty (80%) of patients showed fat replacement progression at FU. The median T1 score progression (ΔT1-score) was 1.3% per year in LB and 0.5% per year in UB. The rate of fat replacement progression was not homogenous, stratifying patients from non-progressors to fast progressors (> 3% ΔT1-score per year). Half of the STIR-positive muscles at BL showed T1-score progression at FU. Two patients with normal MRI at baseline only showed STIR-positive muscle at FU, marking the disease activity onset. STIR positivity at baseline correlated with fat replacement progression (ΔT1-score; p < 0.0001) and clinical worsening at FU (ΔMRC-score; p < 0.0001). Sixty-five (65%) of patients showed STIR- and fat replacement-independent muscle atrophy progression, more evident in UB.
CONCLUSIONS: Muscle MRI represents a sensitive biomarker of disease activity, severity, and progression in DM1. STIR alterations precede fat replacement and identify patients with a higher risk of disease progression, while T1-sequences reveal atrophy and fat replacement progression before clinical worsening.
方法:这是一个前瞻性的,观察,纵向研究包括25例DM1患者进行了至少两次肌肉MRI检查。记录人口统计学和遗传特征。在基线(BL)和随访(FU)时,在MRI的3个月内进行肌肉损伤评定量表(MIRS)和MRC评分。我们通过T1和STIR序列分析了下半身的32条肌肉(LB)和上半身的17条肌肉(UB)。T1-,评估STIR和萎缩评分及其变化。核磁共振成像评分与人口统计之间的相关性,分析了临床和遗传特征。
结果:80例(80%)患者在FU出现脂肪替代进展。中位T1评分进展(ΔT1评分)在LB中为每年1.3%,在UB中为每年0.5%。脂肪替代进展的速度并不均匀,将患者从非进展者分层为快速进展者(每年>3%ΔT1评分)。BL时一半的STIR阳性肌肉在FU时显示T1评分进展。两名基线MRI正常的患者仅在FU显示STIR阳性肌肉,标志着疾病的活动开始。基线时的STIR阳性与脂肪替代进展(ΔT1-评分;p<0.0001)和FU时的临床恶化(ΔMRC-评分;p<0.0001)相关。65(65%)的患者表现出STIR和脂肪替代无关的肌肉萎缩进展,在UB中更明显。
结论:肌肉MRI代表疾病活动的敏感生物标志物,严重程度,和DM1的进展。STIR改变先于脂肪替代,并确定疾病进展风险较高的患者,而T1序列显示临床恶化前的萎缩和脂肪替代进展。