Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27101, USA.
Department of Health and Exercise Science, Wake Forest University, Winston-Salem, North Carolina, 27109, USA.
Muscle Nerve. 2023 Jun;67(6):506-514. doi: 10.1002/mus.27821. Epub 2023 Apr 3.
INTRODUCTION/AIMS: Although muscle structure measures from magnetic resonance imaging (MRI) have been used to assess disease severity in muscular dystrophies, little is known about how these measures are affected in myotonic dystrophy type 2 (DM2). We aim to characterize lower extremity muscle fat fraction (MFF) as a potential biomarker of disease severity, and evaluate its relationship with motor performance in DM2.
3-Tesla MRIs were obtained from nine patients with DM2 and six controls using a T1W-Dixon protocol. To calculate MFF, muscle volumes were segmented from proximal, middle, and distal regions of the thigh and calf. Associations between MFF and motor performance were calculated using Spearman's correlations (ρ).
Mean age of DM2 participants was 62 ± 11 y (89% female), and mean symptom duration was 20 ± 12 y. Compared to controls, the DM2 group had significantly higher MFF in the thigh and the calf segments (p-value = .002). The highest MFF at the thigh in DM2 was located in the posterior compartment (39.7 ± 12.9%) and at the calf was the lateral compartment (31.5 ± 8.7%). In the DM2 group, we found a strong correlation between the posterior thigh MFF and the 6-min walk test (ρ = -.90, p-value = .001). The lateral calf MFF was also strongly correlated with the step test (ρ = -0.82, p-value = .006).
Our pilot data suggest a potential correlation between lower extremity MFF and some motor performance tests in DM2. Longitudinal studies with larger sample sizes are required to validate MFF as a marker of disease severity in DM2.
简介/目的：尽管磁共振成像（MRI）的肌肉结构测量已被用于评估肌肉营养不良症的疾病严重程度，但对于 2 型肌强直性营养不良（DM2）中这些测量值如何受到影响知之甚少。我们旨在将下肢肌肉脂肪分数（MFF）作为疾病严重程度的潜在生物标志物进行特征描述，并评估其与 DM2 运动表现的关系。
使用 T1W-Dixon 方案从 9 例 DM2 患者和 6 例对照中获得 3T MRI。为了计算 MFF，从大腿和小腿的近端、中部和远端区域对肌肉体积进行分割。使用 Spearman 相关系数（ρ）计算 MFF 与运动表现之间的相关性。
DM2 参与者的平均年龄为 62±11 岁（89%为女性），平均症状持续时间为 20±12 年。与对照组相比，DM2 组大腿和小腿各节段的 MFF 明显更高（p 值=0.002）。DM2 中大腿 MFF 最高的部位是后区（39.7±12.9%），小腿是外侧区（31.5±8.7%）。在 DM2 组中，我们发现后大腿 MFF 与 6 分钟步行测试之间存在很强的相关性（ρ=-0.90，p 值=0.001）。小腿外侧 MFF 与步距测试也呈强烈相关性（ρ=-0.82，p 值=0.006）。
我们的初步数据表明，DM2 患者下肢 MFF 与某些运动表现测试之间可能存在相关性。需要进行更大样本量的纵向研究，以验证 MFF 作为 DM2 疾病严重程度的标志物。
