Yonsei University College of Medicine, Seoul, South Korea.
Department of Internal Medicine, Severance Hospital, Endocrine Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.
Calcif Tissue Int. 2021 Jun;108(6):764-774. doi: 10.1007/s00223-021-00812-9. Epub 2021 Feb 10.
Computed tomography (CT)-derived skeletal muscle area (SMA) and skeletal muscle radiodensity (SMD) reflect distinctive quantitative and qualitative characteristics of skeletal muscles. However, data on whether CT-based muscle parameters, especially SMD, can predict muscle function is limited. In a prospective cohort, 1523 community-dwelling older adults who underwent abdominal CT scans and the countermovement two-legged jumping test on a ground reaction force platform were analyzed (mean age 74.7 years, 65.1% women). SMA and SMD were measured at third lumbar vertebra level (L3). Individuals with low jump power (peak weight-corrected jump power < 23.8 W/kg in men and < 19.0 W/kg in women using clinically validated threshold) were older; had lower SMA, SMD, and maximal grip strength values; and had lower chair rise test and timed up and go test performance than those without low jump power. SMD was positively associated with peak weight-corrected jump power (adjusted β = 0.33 and 0.23 per 1 HU increase in men and women, respectively, p < 0.001). One HU decrement in SMD was associated with 10% elevated odds of low jump power (adjusted OR [aOR] 1.10, p < 0.001) after adjusting for age, sex, height, inflammation, and insulin resistance markers, whereas the association of SMA with low jump power was attenuated (aOR 1.00, p = 0.721). SMD showed better discrimination for low jump power than SMA (AUC 0.699 vs. 0.617, p < 0.001), with additional improvement when added to SMA and conventional risk factors (AUC 0.745 to 0.773, p < 0.001). Therefore, CT-measured L3 SMD can be a sensitive surrogate marker for muscle function along with SMA in older adults, which merits further investigation.
计算机断层扫描（CT）衍生的骨骼肌面积（SMA）和骨骼肌辐射密度（SMD）反映了骨骼肌的独特定量和定性特征。然而，关于 CT 肌肉参数，尤其是 SMD 是否可以预测肌肉功能的数据有限。在一项前瞻性队列研究中，对 1523 名接受腹部 CT 扫描和地面反力平台反向移动双腿跳跃测试的社区居住老年人进行了分析（平均年龄 74.7 岁，65.1%为女性）。在第三腰椎水平（L3）测量 SMA 和 SMD。低跳跃力个体（男性使用经过临床验证的阈值，峰值体重校正跳跃力<23.8 W/kg；女性<19.0 W/kg）年龄较大；SMA、SMD 和最大握力值较低；椅子上升试验和计时起立行走试验表现也较差。SMD 与峰值体重校正跳跃力呈正相关（男性和女性分别每增加 1 HU，调整后的β值分别为 0.33 和 0.23，p<0.001）。SMD 降低 1 HU 与低跳跃力的可能性增加 10%相关（调整后的 OR [aOR] 1.10，p<0.001），调整年龄、性别、身高、炎症和胰岛素抵抗标志物后，而 SMA 与低跳跃力的相关性减弱（aOR 1.00，p=0.721）。SMD 对低跳跃力的鉴别能力优于 SMA（AUC 0.699 比 0.617，p<0.001），当与 SMA 和常规危险因素联合使用时，其鉴别能力进一步提高（AUC 0.745 至 0.773，p<0.001）。因此，CT 测量的 L3 SMD 可以作为老年人肌肉功能的敏感替代标志物，与 SMA 一起，这值得进一步研究。
