Feasibility of using chest computed tomography (CT) imaging at the first lumbar vertebra (L1) level to assess skeletal muscle mass: a retrospective study.

Liu S ，Han X ，Li J ，Xie X ，Yang Y ，Jiang W ，Liu L ，Liu Z ... -  《PeerJ》

Assessment of muscle mass using chest computed tomography-based quantitative and qualitative measurements in patients with systemic sclerosis: A retrospective study with cross-sectional and longitudinal analyses.

Sarcopenia has been increasingly studied in systemic sclerosis (SSc), which is one of the most lethal autoimmune diseases, mainly due to lung involvement. Our objective was to study the associations of myopenia and/or myosteatosis with clinical features of SSc and subsequent adverse outcomes. This is a retrospective study with cross-sectional and longitudinal analyses, in which patients with SSc were consecutively included in the outpatient clinic of a tertiary university hospital between 2012 and 2021. Clinical and laboratory parameters of patients with SSc were collected from their medical records. Skeletal muscle mass was assessed on chest computed tomography (CT) at the level of the first lumbar vertebra (L1) by skeletal muscle area (SMA), skeletal muscle index ([SMI] SMA/height2), and skeletal muscle radiation attenuation (SMRA). Cut-off values for myopenia in women and men were SMA <70.1 cm² and <110.4 cm², and SMI <25.9 cm²/m² and <34.6 cm²/m², respectively; values for myosteatosis in women and men were SMRA <29.8 HU and <36.3 HU, respectively. In a subgroup of 31 patients followed-up between 2017 and 2019, the diagnostic properties of SMA, SMI, and SMRA by CT were compared with the appendicular skeletal muscle mass index (ASMI) by dual-energy X-ray absorptiometry (DXA). Low muscle quantity was defined according to the European Working Group on Sarcopenia in Older People 2: ASMI <5.5 kg/m2 in women and <7.0 kg/m2 in men. Afterwards, a better tomographic index was used for correlating with clinical and laboratory parameters. Myopenia and/or myosteatosis were present in 75.7 % of patients with SSc. The prevalence rates according to each index were SMA 25.2%, SMI 12.1%, and SMRA 69.2%. In 73% of the patients with overweight/obesity (body mass index [BMI] ≥25 kg/m²), only SMRA was reduced. Considering ASMI as the gold standard, the sensitivity, specificity, positive and negative predictive values for SMA were 60%, 96.2%, 75% and 92.6%, respectively; for SMI, they were 40%, 96.2%, 66.7%, and 89.3%, respectively; for SMRA, these values were 60%, 34.6%, 15%, and 81.8%. Pearson's correlation coefficients were 0.73, 0.74, and 0.10 for SMA, SMI, and SMRA, respectively, and ASMI significantly agreed with SMA (kappa 0.611, p < 0.001) and SMI (kappa 0.431, p = 0.012). After adjustments in a multivariate model, BMI (p < 0.001) and female sex (p < 0.001) remained significantly associated with myopenia by SMA; BMI (p =0.010) remained significantly associated with low muscle mass by ASMI. The SMA index at L1 level on chest CT was demonstrated to be an accurate measure that is useful for detecting myopenia in patients with SSc. BMI and male sex predicted low SMA and BMI was associated with low ASMI on DXA. In recent years, great advances have been made in sarcopenia-related research, resulting in broader knowledge on its definition, causes, diagnosis, and treatment options. Regarding the techniques used for assessing muscle composition, computed tomography (CT) was demonstrated by many studies to be an efficient and easy-to-use method that can be employed by professionals of different specialties, including rheumatologists. This study was able to demonstrate that although the L3 image was not present on CT, the analysis of SMA at the L1 level on chest CT proved to be an accurate and useful measure to detect myopenia in patients with SSc. This study identified some associated factors of myopenia and/or myosteatosis according to each method employed for assessing muscle composition. Reduced BMI and male sex were associated factors of myopenia when using SMA, and reduced BMI was associated with myopenia when employing ASMI by DXA. Finally, we highlight the need not to generalize the term "sarcopenia" in clinical studies assessing imaging parameters of body composition. The use of the terms myopenia and/or myosteatosis would be more adequate, because CT allows the assessment of muscle composition and not strength or physical performance.

da Rocha DS ，Tessari JA ，Mainardi NB ，Hax V ，Gasparin AA ，de Oliveira CAV ，Garcia TS ，Xavier RM ，Chakr RMDS ... -  《-》

Defining reference values for low skeletal muscle index at the L3 vertebra level based on computed tomography in healthy adults: A multicentre study.

Skeletal muscle mass loss is an important aspect of malnutrition and is closely related to adverse clinical outcomes. Computed tomography (CT) is the gold standard for analysing muscle mass, and the skeletal muscle index at the third lumbar vertebra (L3-SMI), measured using CT, is an important indicator to evaluate total skeletal tissue. The aims of this study were to establish reference values for low L3-SMI in Northern China, and to investigate the correlation between L3-SMI and age, and the correlation between L3-SMI and body mass index (BMI). This was a multicentre, retrospective, cross-sectional study. A search of abdominal CT imaging reports, using specific keywords, was conducted in four representative cities in northern China, from January 2016 to March 2021. Transverse CT images at the level of the third lumbar vertebra (L3) were identified, exported from the Radiology Information System, and measured using the analysis software SliceOmatic. Statistical analyses were performed using SPSS 24.0, and significance level was set at p < 0.05. Mean, standard deviations (SD) and percentiles (p5, p10, p25, p50, p75, p90, p95) were used to describe the distribution of L3-SMI in the study population. Low skeletal muscle index was defined as a 5% percentile, or two standard deviations below the mean value of younger healthy individuals (age 20-39 years). The study included 1787 healthy individuals, with a median age of 45 (25) years (range 20-88 years), and a median BMI of 23.1 (4.1) kg/m2 (range 18.5-38.7 kg/m2). Among them, 700 healthy individuals (39.1%) were aged 20-39 years. L3-SMI had a negative linear correlation with age, and a positive linear correlation with BMI. The L3-SMI reference values used to define low skeletal muscle mass loss in the Northern Chinese population, using the 5% percentile, were 40.2 cm2/m2 in men, and 31.6 cm2/m2 in women. Using the mean minus two standard deviations protocol, the reference values were 37.9 cm2/m2 and 28.6 cm2/m2 in men and women, respectively. This study analysed the human body composition of 1787 healthy people in four cities in northern China, using CT, and established diagnostic thresholds of skeletal muscle mass depletion based on 700 younger healthy adults, using the 5% percentile and mean-2SD methods. These reference values can be used to diagnose malnutrition in patients and may aide clinicians in predicting prognosis and improving nutritional therapy. Further research is warranted to determine the prognostic role of reference values against clinical outcomes in different disease populations.

Kong M ，Geng N ，Zhou Y ，Lin N ，Song W ，Xu M ，Li S ，Piao Y ，Han Z ，Guo R ，Yang C ，Luo N ，Wang Z ，Jiang M ，Wang L ，Qiu W ，Li J ，Shi D ，Li R ，Cheung EC ，Chen Y ，Duan Z ... -  《-》

Computed tomography-determined skeletal muscle density predicts 3-year mortality in initial-dialysis patients in China.

Skeletal muscle mass and quality assessed by computed tomography (CT) images of the third lumbar vertebra (L3) level have been established as risk factors for poor clinical outcomes in several illnesses, but the relevance for dialysis patients is unclear. A few studies have suggested a correlation between CT-determined skeletal muscle mass and quality at the first lumbar vertebra (L1) level and adverse outcomes. Generally, chest CT does not reach beyond L1. We aimed to determine whether opportunistic CT scan (chest CT)-determined skeletal muscle mass and quality at L1 are associated with mortality in initial-dialysis patients. This 3-year multicentric retrospective study included initial-dialysis patients from four centres between 2014 and 2017 in China. Unenhanced CT images of the L1 and L3 levels were obtained to assess skeletal muscle mass [by skeletal muscle index, (SMI), cm2 /m2 ] and quality [by skeletal muscle density (SMD), HU]. Skeletal muscle measures at L1 were compared with those at L3. The sex-specific optimal cutoff values of L1 SMI and L1 SMD were determined in relation to all-cause mortality. The outcomes were all-cause death and cardiac death. Cox regression models were applied to investigate the risk factors for death. A total of 485 patients were enrolled, of whom 257 had both L1 and L3 images. Pearson's correlation coefficient between L1 and L3 SMI was 0.84 (P < 0.001), and that between L1 and L3 SMD was 0.90 (P < 0.001). No significant association between L1 SMI and mortality was observed (P > 0.05). Low L1 SMD (n = 280, 57.73%) was diagnosed based on the optimal cutoff value (<39.56 HU for males and <33.06 HU for females). Multivariate regression analysis revealed that the low L1 SMD group had higher risks of all-cause death (hazard ratio 1.80; 95% confidence interval 1.05-3.11, P = 0.034) and cardiac death (hazard ratio 3.74; 95% confidence interval 1.43-9.79, P = 0.007). In initial-dialysis patients, there is high agreement between the L1 and L3 measures for SMI and SMD. Low SMD measured at L1, but not low SMI, is an independent predictor of both all-cause death and cardiac death.

Sheng MJ ，Cao JY ，Hou SM ，Li M ，Wang Y ，Fang Q ，Miao AF ，Yang M ，Liu SS ，Hu CH ，Liu CL ，Wang SY ，Zheng J ，Xiao JJ ，Zhang XL ，Liu H ，Liu BC ，Wang B ... -  《-》

Cut-off values of skeletal muscle index and psoas muscle index at L3 vertebra level by computerized tomography to assess low muscle mass.

Computerized tomography (CT) is considered the gold standard for the evaluation of total skeletal muscle quantity. Skeletal muscle assessments at the L3 vertebra level revealed significantly correlated with total body muscle measurements. Clinicians need cut-offs to evaluate low muscle mass in various patients who already had CT imaging without any additional cost. This assessment is important to help the physicians to stratify the patients for mortality and other complications. It may also enable the diagnosis of malnutrition by the GLIM criteria. Few studies reported cut-offs in different populations. We aimed to provide cut-off values for total skeletal muscle index (SMI) and psoas muscle mass index (PMI) at the L3 vertebra level in the Turkish population. We assessed the preoperative plain CT images of living adult liver donors who were admitted to a single transplantation center between June 2010 and April 2018. We derived cut-off values with two alternative methods, the 5th percentile value or mean minus two standard deviations and from two groups of study participants, i.e. the total study population and the younger subgroup aged between 18 and 40. The study population involved 601 subjects with a mean age of 32.5 ± 9 (range: 18-59 years) and 326 (54.2%) was male. The younger subgroup was composed of 482 individuals with a mean age of 28.8 ± 5.9 and 55.6% male. In patients aged between 18 and 40, PMI and SMI cut-offs by using the 5th percentile were 5.40 cm2/m2, 41.42 cm2/m2 for males; and 3.56 cm2/m2, 30.70 cm2/m2 for females; respectively. The cut-offs of PMI and SMI by using mean minus two standard deviations were 4.62 cm2/m2, 38.67 cm2/m2 for males; and 2.66 cm2/m2, 27.8 cm2/m2 for females; respectively. These cut-offs were comparable to the other populations. Our study provided cut-offs to be used in CT images for PMI and SMI. There is a need for further longitudinal studies to verify whether these cut-offs are successful in predicting mortality or other adverse outcomes associated with low muscle mass.

Bahat G ，Turkmen BO ，Aliyev S ，Catikkas NM ，Bakir B ，Karan MA ... -  《-》