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) 反映了骨骼肌独特的定量和定性特征。然而，关于基于 CT 的肌肉参数，尤其是 SMD，是否可以预测肌肉功能的数据是有限的。在一项前瞻性队列研究中，对 1523 名接受腹部 CT 扫描和地面反作用力平台上反向运动双腿跳跃测试的社区老年人进行了分析（平均年龄 74.7 岁，女性占 65.1%）。在第三腰椎水平 (L3) 测量 SMA 和 SMD。具有低跳跃力的个体（使用经临床验证的阈值，男性的峰值体重校正跳跃力 < 23.8 W/kg，女性 < 19.0 W/kg）年龄较大；具有较低的 SMA、SMD 和最大握力值；并且比那些没有低跳跃力的人有更低的椅子上升测试和计时和去测试性能。SMD 与峰值重量校正跳跃力呈正相关（调整β  = 0.33 和 0.23，男性和女性每 1 HU 增加，p  < 0.001）。 在调整年龄、性别、身高、炎症和胰岛素抵抗标志物后，SMD 中 HU 减少 1 与低跳跃能力的几率增加 10%（调整后的 OR [aOR] 1.10，p < 0.001）相关，而 SMA 与低跳跃力减弱（aOR 1.00，p  = 0.721）。SMD 显示出比 SMA 更好的低跳跃力辨别力（AUC 0.699 对 0.617，p  < 0.001），当添加到 SMA 和传统风险因素（AUC 0.745 到 0.773，p < 0.001)。因此，CT 测量的 L3 SMD 可以与老年人的 SMA 一起作为肌肉功能的敏感替代指标，值得进一步研究。