Whole-body patterns of muscle degeneration and progression in sarcoglycanopathies

MRI studies were performed following standard protocols, either WB(Carlier & Quijano-Roy, 2019; Chardon et al., 2019; Quijano-Roy et al., 2012) or combination of UB and LB MRI(Tasca et al., 2012, 2014), using different 1.5T or 3T scanners, and T1-weighted images were analyzed.A total of 65 muscles on both sides were independently evaluated for each scan by two independent observers, a radiologist and a pediatric neurologist with experience in muscle imaging (AS and LC). In case of discrepancy between the evaluators, agreement was reached by consensus (AS, DGA and LC). The median scores from both sides were used for data analysis. A four-point modified Lamminen scale was used to evaluate signal abnormalities representative of the extent of intramuscular fatty replacement in each muscle as follows: 0= normal signal intensity, 1=slightly hyperintense, patchy intramuscular signal changes 2=markedly hyperintense and widespread intramuscular signal changes, 3= total, homogeneous hyperintense signal change in whole muscle, equaling the signal intensity of the adjacent subcutaneous or paramuscular fat, or atrophy(Chardon et al., 2019; Lamminen, 1990; Wattjes et al., 2010). The scores of muscles that were not adequately visualized were considered as missing values (NA). The lower limb scans analyzed in the previous imaging study(Tasca et al., 2018) with a 5-point scoring system were re-scored to address the limitations in assessing some of the small and flat muscles in the head, trunk, neck and arms, ensuring uniformity across all body regions.

本研究遵循标准方案开展磁共振成像（Magnetic Resonance Imaging, MRI）扫描，扫描方案分为全身MRI（WB，引用文献Carlier & Quijano-Roy, 2019; Chardon et al., 2019; Quijano-Roy et al., 2012）以及上肢MRI与下肢MRI联合扫描（UB+LB MRI，引用文献Tasca et al., 2012, 2014）两种，扫描设备涵盖不同型号的1.5T及3T磁共振扫描仪，所有扫描均对T1加权成像（T1-weighted imaging）图像进行分析。每例扫描图像均由两名独立阅片者分别评估双侧共计65块肌肉，两名阅片者分别为具有肌肉影像学阅片经验的放射科医师及儿科神经科医师（缩写AS与LC）。当两名阅片者评估结果存在分歧时，由三人（AS、DGA及LC）通过共识讨论达成一致意见。取双侧肌肉评分的中位数用于后续数据分析。本研究采用改良Lamminen四分量表（Lamminen scale）对每块肌肉的肌内脂肪替代程度相关信号异常进行评估，评分标准如下：0分：信号强度正常；1分：轻度高信号，伴斑片状肌内信号改变；2分：显著高信号，伴弥漫性肌内信号改变；3分：整块肌肉出现完全均匀的高信号改变，信号强度与邻近皮下脂肪或肌旁脂肪一致，或伴肌肉萎缩（引用文献Chardon et al., 2019; Lamminen, 1990; Wattjes et al., 2010）。对于显像不充分的肌肉，其评分为缺失值（Not Available, NA）。本研究对既往影像学研究（Tasca et al., 2018）中采用五分量表评估的下肢扫描图像进行重新评分，以解决原方案在评估头、躯干、颈部及上肢部分细小扁平肌肉时存在的局限性，确保全身各部位评估标准统一。