Department of Neurology, BG-University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany.
Department of Neurology, Klinikum Dortmund, University Witten-Herdecke, Dortmund, Germany.
J Neuromuscul Dis. 2024;11(5):997-1009. doi: 10.3233/JND-240053.
Sporadic inclusion body myositis (sIBM) is the predominant idiopathic inflammatory myopathy (IIM) in older people. Limitations of classical clinical assessments have been discussed as possible explanations for failed clinical trials, underlining the need for more sensitive outcome measures. Quantitative muscle MRI (qMRI) is a promising candidate for evaluating and monitoring sIBM.
Longitudinal assessment of qMRI in sIBM patients.
We evaluated fifteen lower extremity muscles of 12 sIBM patients (5 females, mean age 69.6, BMI 27.8) and 12 healthy age- and gender-matched controls. Seven patients and matched controls underwent a follow-up evaluation after one year. Clinical assessment included testing for muscle strength with Quick Motor Function Measure (QMFM), IBM functional rating scale (IBM-FRS), and gait analysis (6-minute walking distance). 3T-MRI scans of the lower extremities were performed, including a Dixon-based sequence, T2 mapping and Diffusion Tensor Imaging. The qMRI-values fat-fraction (FF), water T2 relaxation time (wT2), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (λ1), and radial diffusivity (RD) were analysed.
Compared to healthy controls, significant differences for all qMRI parameters averaged over all muscles were found in sIBM using a MANOVA (p < 0.001). In low-fat muscles (FF < 10%), a significant increase of wT2 and FA with an accompanying decrease of MD, λ1, and RD was observed (p≤0.020). The highest correlation with clinical assessments was found for wT2 values in thigh muscles (r≤-0.634). Significant changes of FF (+3.0%), wT2 (+0.6 ms), MD (-0.04 10-3mm2/s), λ1 (-0.05 10-3mm2/s), and RD (-0.03 10-3mm2/s) were observed in the longitudinal evaluation of sIBM patients (p≤0.001). FA showed no significant change (p = 0.242).
qMRI metrics correlate with clinical findings and can reflect different ongoing pathophysiological mechanisms. While wT2 is an emerging marker of disease activity, the role of diffusion metrics, possibly reflecting changes in fibre size and intracellular deposits, remains subject to further investigations.
散发性包涵体肌炎（sIBM）是老年人中主要的特发性炎性肌病（IIM）。人们讨论了经典临床评估的局限性，认为这可能是临床试验失败的原因，这突显了需要更敏感的疗效评估指标。定量肌肉磁共振成像（qMRI）是评估和监测 sIBM 的一种很有前途的候选方法。
对 sIBM 患者进行 qMRI 的纵向评估。
我们评估了 12 名 sIBM 患者（5 名女性，平均年龄 69.6 岁，BMI 27.8）和 12 名年龄和性别匹配的健康对照者的 15 条下肢肌肉。其中 7 名患者和匹配的对照组在一年后进行了随访评估。临床评估包括使用快速运动功能测量（QMFM）、IBM 功能评分（IBM-FRS）和步态分析（6 分钟步行距离）测试肌肉力量。对下肢进行了 3T-MRI 扫描，包括基于 Dixon 的序列、T2 映射和弥散张量成像。分析了 qMRI 值脂肪分数（FF）、水 T2 弛豫时间（wT2）、各向异性分数（FA）、平均弥散系数（MD）、轴向弥散系数（λ1）和径向弥散系数（RD）。
与健康对照组相比，使用 MANOVA 在 sIBM 患者中发现所有 qMRI 参数在所有肌肉上的平均值均有显著差异（p＜0.001）。在低脂肪肌肉（FF＜10%）中，观察到 wT2 和 FA 显著增加，同时 MD、λ1 和 RD 显著降低（p≤0.020）。与临床评估相关性最高的是大腿肌肉的 wT2 值（r≤-0.634）。在 sIBM 患者的纵向评估中，观察到 FF（增加 3.0%）、wT2（增加 0.6 ms）、MD（减少 0.04 10-3mm2/s）、λ1（减少 0.05 10-3mm2/s）和 RD（减少 0.03 10-3mm2/s）的显著变化（p≤0.001）。FA 没有显示出显著变化（p=0.242）。
qMRI 指标与临床发现相关，并能反映不同的持续病理生理机制。虽然 wT2 是疾病活动的新兴标志物，但扩散指标的作用（可能反映纤维大小和细胞内沉积物的变化）仍有待进一步研究。
