Background

Although computed tomography (CT) is considered the gold standard for investigating skeletal muscles, diagnostic cut-off points for sarcopenia have not been established. We therefore suggested clinically relevant diagnostic cut-off points for sarcopenia based on reference values of skeletal muscle area (SMA) measured by CT scan in a large-sized healthy Asian population.

Methods

This cross-sectional analysis included 11,845 subjects (7,314 men, 4,531 women) who underwent abdominal CT scans in South Korea. SMA including all muscles on the selected axial images of the L3 lumbar vertebrae level was demarcated using predetermined thresholds (-29 to +150 Hounsfield units). SMA indices (height-, weight-, BMI-adjusted) were calculated.

Results

When T-score < -2.0 was used as the cut-off for defining sarcopenia, the sex-specific cut-off points of SMA, SMA/height², SMA/weight, and SMA/BMI were 119.3 cm² and 74.2 cm², 39.8 cm²/m² and 28.4 cm²/m², 1.65 cm²/kg and 1.38 cm²/kg, and 4.97 and 3.46 in men and women, respectively. In both sexes, the SMA/BMI values peaked in the 20s and decreased gradually. The SMA/BMI yielded the highest diagnostic rate of sarcopenia (4.2% in men, 8.7% in women), while SMA/height² provided the lowest yield (2.8% in men, 1.0% in women).

Conclusions

This is the first study to report the reference values of SMA and SMIs measured on CT scans and to suggest cut-off points for diagnosis of sarcopenia based on T-score in Asian subjects. BMI-adjusted index (SMA/BMI) was the best index of CT-measured SMA to reflect the age-related muscle changes and to maximize the diagnostic yield for sarcopenia.

中文翻译：

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健康朝鲜族人群的CT扫描测量腰椎骨骼肌区域的参考数据和T分数及其骨骼肌指标

背景

尽管计算机断层扫描（CT）被认为是研究骨骼肌的黄金标准，但肌肉减少症的诊断临界点尚未建立。因此，我们建议根据亚洲人健康的大型CT扫描测量的骨骼肌面积（SMA）的参考值，为肌肉减少症提供临床相关的诊断临界点。

方法

这项横断面分析包括在韩国接受腹部CT扫描的11,845名受试者（7,314名男性，4,531名女性）。使用预定阈值（-29至+150 Hounsfield单位）划定了SMA，包括L3腰椎水平的所选轴向图像上的所有肌肉。计算SMA指数（高度，体重，BMI调整后）。

结果

当使用T评分<-2.0作为定义少肌症的临界值时，SMA，SMA /身高²，SMA /体重和SMA / BMI的性别特定临界点分别为119.3 cm ²和74.2 cm ²，39.8厘米² /米²和28.4厘米² /米²，1.65厘米² 1.38厘米/ kg和²，分别/ kg和4.97和3.46男性和女性。在男女中，SMA / BMI值均在20年代达到峰值，然后逐渐下降。SMA / BMI导致肌肉减少症的诊断率最高（男性为4.2％，女性为8.7％），而SMA /身高^2的诊断率最低（男性为2.8％，女性为1.0％）。

结论

这是第一项报告在CT扫描中测得的SMA和SMI的参考值，并为亚洲受试者提供基于T评分的诊断少肌症的临界点的第一项研究。BMI调整指数（SMA / BMI）是CT测量的SMA的最佳指数，可以反映与年龄相关的肌肉变化并最大程度地减少肌肉减少症的诊断率。