Abstract:

Objective Quantitative CT was used to investigate the relationship between skeletal muscle and fatty degree of L3 vertebral plane and sarcopenia in the elderly. Methods The CT images and clinical data of 200 patients who underwent abdominal CT scan in the 2nd Hospital of Hebei Medical University from January 2020 to August 2020 were retrospectively analyzed. According to the diagnostic criteria of Asian sarcopenia working group，they were divided into sarcopenia group（n = 16）and non⁃sarcopenia group（n = 184）.“X Section”software of GE ADW4.6 workstation was used to quantitatively measure the skeletal muscle and intermuscular fat of L3 verte⁃ bral plane，and the area and average CT value were recorded. The skeletal muscle area of L3 vertebral plane（L3 SMA），body surface area（BSA），L3 vertebral area and height were standardized in different ways. Chi⁃square test or Fisher′s exact test was used to compare the differences between enumeration data in the two groups. Independent sample t test or nonparametric rank sum test（Mann⁃Whitney U test）was used to compare the differences between the measurement data in two groups. Receiver operating characteristic（ROC）curve was used to analyze the skeletal muscle area of L3 vertebral plane and the effectiveness of different standardized results in the diagnosis of sarcope⁃ nia. Results There were 16 cases（8.00%）diagnosed as sarcopenia，including 6 males（3.00%）and 10 females （5.00%）. There was no significant difference in gender，age between the two groups（P＞0.05）. BMI in sarcope⁃ nia group was lower than that in non⁃sarcopenia group，The difference was statistically significant（P＜0.05）. The L3 SMA，average density of total skeletal muscle in L3 vertebral plane（L3 SMD）and muscle space area of the non⁃ sarcopenia group were higher than those of the sarcopenia group，but only L3 SMA had significant difference between the two groups（P＜0.05）. ROC curve analysis showed that L3 SMA was standardized by the BSA（L3 SMB）had the highest diagnostic efficiency for sarcopenia，with area under the curve of 0.802，sensitivity of 73.9% and specificity of 75.0% . Conclusions The incidence of sarcopenia was 8.00% in the elderly. CT quantitative measurement of skeletal muscle has high reliability. The sensitivity and specificity of L3 SMB in the diagnosis of sarcopenia were 73.9% and 75.0%，respectively. The optimal critical values for male and female sarcopenia were 435.15 cm2 /m2 and 365.08 cm2 /m2，respectively. 

Key words:

sarcopenia, elderly, L3 skeletal muscle index, computed tomograph