Comparison of CT derived body composition at the thoracic T4 and T12 with lumbar L3 vertebral levels and their utility in patients with rectal cancer.

Computed tomography (CT) derived body composition measurements of sarcopenia are an emerging form of prognostication in many disease processes. Although the L3 vertebral level is commonly used to measure skeletal muscle mass, other studies have suggested the utilisation of other segments. This study was performed to assess the variation and reproducibility of skeletal muscle mass at vertebral levels T4, T12 and L3 in pre-operative rectal cancer patients. If thoracic measurements were equivalent to those at L3, it will allow for body composition comparisons in a larger range of cancers where lumbar CT images are not routinely measured. Patients with stage I - III rectal cancer, undergoing curative resection from 2010 - 2014, were assessed. CT based quantification of skeletal muscle was used to determine skeletal muscle cross sectional area (CSA) and skeletal muscle index (SMI). Systematic differences between the measurements at L3 with T4 and T12 vertebral levels were evaluated by percentile rank differences to assess distribution of differences and ordinary least product regression (OLP) to detect and distinguish fixed and proportional bias. Eighty eligible adult patients were included. Distribution of differences between T12 SMI and L3 SMI were more marked than differences between T4 SMI and L3 SMI. There was no fix or proportional bias with T4 SMI, but proportional bias was detected with T12 SMI measurements. T4 CSA duplicate measurements had higher test-retest reliability: coefficient of repeatability was 34.10 cm2 for T4 CSA vs 76.00 cm2 for T12 CSA. Annotation time (minutes) with L3 as reference, the median difference was 0.85 for T4 measurements and -0.03 for T12 measurements. Thirty-seven patients (46%) had evidence of sarcopenia at the L3 vertebral level, with males exhibiting higher rates of sarcopenia. However, there was no association between sarcopenia and post-operative complications, recurrence or hospital LOS (length of stay) in patients undergoing curative resection. Quantifying skeletal muscle mass at the T4 vertebral level is comparable to measures achieved at L3 in patients with rectal cancer, notwithstanding annotation time for T4 measurements are longer.

Arayne AA ，Gartrell R ，Qiao J ，Baird PN ，Yeung JM ... -  《BMC CANCER》

Diagnosis of Sarcopenia Using the L3 Skeletal Muscle Index Estimated From the L1 Skeletal Muscle Index on MR Images in Patients With Cirrhosis.

Cirrhotic patients with sarcopenia have poor prognoses and higher mortality. The third lumbar vertebra (L3) skeletal muscle index (SMI) is widely used to assess sarcopenia. However, L3 is generally outside the scanning volume on standard liver MRI. To investigate SMIs change between slices in cirrhotic patients and the relationships between SMI at the 12th thoracic vertebra (T12), the first lumbar vertebra (L1) and the second lumbar vertebra (L2) levels and L3-SMI and assess the accuracy of the estimated L3-SMIs in diagnosing sarcopenia. Prospective. A total of 155 cirrhotic patients (109 with sarcopenia, 67 male; 46 without sarcopenia, 18 male). A 3.0 T, 3D dual-echo T1-weighted gradient echo sequence (T1WI). Two observers analyzed T12 to L3 skeletal muscle area (SMA) in each patient based on T1W water images and calculated the SMI (SMA/height2 ). Reference standard was L3-SMI. Intraclass correlation coefficient (ICC), Pearson correlation coefficients (r), and Bland-Altman plots. Models relating L3-SMI to the SMI at T12, L1, and L2 levels were constructed using 10-fold cross-validation. Accuracy, sensitivity, and specificity were calculated for the estimated L3-SMIs for diagnosing sarcopenia. P < 0.05 was considered statistically significant. Intraobserver and interobserver ICCs were 0.998-0.999. The L3-SMA/L3-SMI were correlated with the T12 to L2 SMA/SMI (r = 0.852-0.977). T12-L2 models had mean-adjusted R2 values of 0.75-0.95. The estimated L3-SMI from T12 to L2 levels to diagnose sarcopenia had good accuracy (81.4%-95.3%), sensitivity (88.1%-97.0%), and specificity (71.4%-92.9%). The recommended L1-SMI threshold of 43.24 cm2 /m2 in males and 33.73 cm2 /m2 in females. The estimated L3-SMI from T12, L1 and L2 levels had good diagnostic accuracy in assessing sarcopenia in cirrhotic patients. Although L2 was best associated with L3-SMI, L2 is generally not included in standard liver MRI. L3-SMI estimate from L1 may therefore be most clinically applicable. 1. Stage 2.

Xu Z ，Yang D ，Luo J ，Xu H ，Jia J ，Yang Z ... -  《-》

Percentile-based averaging and skeletal muscle gauge improve body composition analysis: validation at multiple vertebral levels.

Skeletal muscle metrics on computed tomography (CT) correlate with clinical and patient-reported outcomes. We hypothesize that aggregating skeletal muscle measurements from multiple vertebral levels and skeletal muscle gauge (SMG) better predict outcomes than skeletal muscle radioattenuation (SMRA) or -index (SMI) at a single vertebral level. We performed a secondary analysis of prospectively collected clinical (overall survival, hospital readmission, time to unplanned hospital readmission or death, and readmission or death within 90 days) and patient-reported outcomes (physical and psychological symptom burden captured as Edmonton Symptom Assessment Scale and Patient Health Questionnaire) of patients with advanced cancer who experienced an unplanned admission to Massachusetts General Hospital from 2014 to 2016. First, we assessed the correlation of skeletal muscle cross-sectional area, SMRA, SMI, and SMG at one or more of the following thoracic (T) or lumbar (L) vertebral levels: T5, T8, T10, and L3 on CT scans obtained ≤50 days before index assessment. Second, we aggregated measurements across all available vertebral levels using percentile-based averaging (PBA) to create the average percentile. Third, we constructed one regression model adjusted for age, sex, sociodemographic factors, cancer type, body mass index, and intravenous contrast for each combination of (i) vertebral level and average percentile, (ii) muscle metrics (SMRA, SMI, & SMG), and (iii) clinical and patient-reported outcomes. Fourth, we compared the performance of vertebral levels and muscle metrics by ranking otherwise identical models by concordance statistic, number of included patients, coefficient of determination, and significance of muscle metric. We included 846 patients (mean age: 63.5 ± 12.9 years, 50.5% males) with advanced cancer [predominantly gastrointestinal (32.9%) or lung (18.9%)]. The correlation of muscle measurements between vertebral levels ranged from 0.71 to 0.84 for SMRA and 0.67 to 0.81 for SMI. The correlation of individual levels with the average percentile was 0.90-0.93 for SMRA and 0.86-0.92 for SMI. The intrapatient correlation of SMRA with SMI was 0.21-0.40. PBA allowed for inclusion of 8-47% more patients than any single-level analysis. PBA outperformed single-level analyses across all comparisons with average ranks 2.6, 2.9, and 1.6 for concordance statistic, coefficient of determination, and significance (range 1-5, μ = 3), respectively. On average, SMG outperformed SMRA and SMI across outcomes and vertebral levels: the average rank of SMG was 1.4, 1.4, and 1.4 for concordance statistic, coefficient of determination, and significance (range 1-3, μ = 2), respectively. Multivertebral level skeletal muscle analyses using PBA and SMG independently and additively outperform analyses using individual levels and SMRA or SMI.

Marquardt JP ，Roeland EJ ，Van Seventer EE ，Best TD ，Horick NK ，Nipp RD ，Fintelmann FJ ... -  《-》

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》

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 ... -  《-》