Abstract：
BACKGROUND: Myotonic dystrophy type 1 (DM1) is an autosomal dominant disease characterized by myotonia and progressive muscular weakness and atrophy. The aim of this study was to investigate the usefulness of longitudinal muscle MRI in detecting disease activity and progression in DM1, and to better characterize muscle edema, fat replacement and atrophy overtime.
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.
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.
摘要：
背景：强直性肌营养不良1型（DM1）是一种常染色体显性疾病，其特征是肌强直和进行性肌肉无力和萎缩。这项研究的目的是研究纵向肌肉MRI在检测DM1疾病活动和进展中的有用性，并更好地表征肌肉水肿，脂肪替代和萎缩加班。
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。
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。
