CT-derived Muscle Research Articles

CT-derived Chest Muscle Metrics for Outcome Prediction in Patients with COVID-19.

BackgroundLower muscle mass is a known predictor of unfavorable outcome, but its prognostic impact on COVID-19 patients is unknown.PurposeTo investigate the contribution of CT-derived muscle status in predicting clinical outcomes in COVID-19 patients.Materials and MethodsClinical/laboratory data and outcomes (intensive care unit [ICU] admission and death) were retrospectively retrieved for patients with reverse transcriptase polymerase chain reaction-confirmed COVID-19, who underwent chest CT on admission in four hospitals in Northern Italy from February 21 to April 30, 2020. Extent and type of pulmonary involvement, mediastinal lymphadenopathy, and pleural effusion were assessed. Cross-sectional areas and attenuation of paravertebral muscles were measured on axial CT images at T5 and T12 vertebral level. Multivariable linear and binary logistic regression, including calculation odds ratios (OR) with 95% confidence intervals (CIs), were used to build four models to predict ICU admission and death, tested and compared using receiver operating characteristic curve (ROC) analysis.ResultsA total 552 patients (364 men; median age 65 years, interquartile range 54–75) were included. In a CT-based model, lower-than-median T5 paravertebral muscle area showed the highest ORs for ICU admission (OR 4.8, 95% CI 2.7–8.5; P<.001) and death (OR 2.3, 95% CI 1.0–2.9; P=.027). When clinical variables were included in the model, lower-than-median T5 paravertebral muscle area still showed the highest ORs both for ICU admission (OR 4.3; 95% CI 2.5–7.7; P<.001) and death (OR 2.3, 95% CI 1.3–3.7; P=.001). At ROC analysis, the CT-based model and the model including clinical variables showed the same area under the curve (AUC) for ICU admission prediction (AUC 0.83, P=.380) and were not different in predicting death (AUC 0.86 versus AUC 0.87, respectively, P=.282).ConclusionIn hospitalized patients with COVID-19, lower muscle mass on CT was independently associated with ICU admission and hospital mortality.

Baseline CT-derived muscle quality influences post-operative morbidity and five-year survival following pancreatic surgery

Purpose: Concerns regarding rapid disease progression have delayed the translation and evaluation of prehabilitation in patients with pancreatic cancer (PC). This study sought to investigate the association between baseline CT-derived muscle indices and post-operative outcome following pancreatic surgery. Methods: Consecutive patients who underwent surgery for suspected pancreatic malignancy at a tertiary, high-volume centre between 2010 and 2013 were identified, and patient status censored on 31st December 2018 to allow a minimum five-year follow up period for all participants. Major post-operative morbidity was defined as per Clavien-Dindo classification (>3). Individual muscle mass and attenuation were measured at the third lumbar vertebrae (L3) using Slice-O-Matic software, and pre-defined BMI- and gender-specific cut-offs applied. Associations between muscle indices and the occurrence of post-operative complications was assessed using binary logistic regression analysis, with results reported as odds ratios (OR) and corresponding 95% confidence intervals. The log-rank (Mantel- Cox) test was used to assess the influence of muscle indices on overall survival. Results: Sarcopenia and low muscle attenuation (MA) were present in 46% and 52% of patients respectively (n=276). Low MA was associated with increased post-operative morbidity (OR 1.6, 95% CI 1.07 -2.19, p=0.029), while both sarcopenia and low MA were associated with reduced overall survival (41 vs 62 months, p=0.036, 29 vs 61 months, p=0.0001 respectively). When patients with pathologically confirmed PC were evaluated separately (n=107), the influence of muscle indices on survival were sustained (sarcopenia 16 vs 26 months, p=0.017, low MA 12 vs 30 months, p= 0.016). Conclusion: Low MA and sarcopenia were prevalent among patients undergoing surgery for suspected pancreatic malignancy. Both factors were associated with increased mortality risk and shorter overall survival, while low muscle attenuation was associated with increased major post-operative morbidity risk. CT-derived muscle assessment could aid patient selection and risk stratification for pancreatic cancer, both by identifying a vulnerable patient cohort in need of pre-operative optimisation, and providing an objective assessment parameter for the evaluation of targeted interventions.

Diagnosing sarcopenia at the point of imaging care: analysis of clinical, functional, and opportunistic CT metrics.

To determine the relationship between CT-derived muscle metrics and standardized metrics of sarcopenia in patients undergoing routine CT imaging. Data collected in 443 consecutive patients included body CT, grip strength, usual gait speed, and responses to SARC-F and FRAIL scale questionnaires. Functional and clinical metrics of sarcopenia were acquired at the time of CT. Metrics were analyzed using the diagnostic framework of the European Working Group on Sarcopenia in Older People (EWGSOP2). The skeletal muscle index (SMI) and skeletal muscle density (SMD) were measured at the T12 and L3 levels. Statistical methods include linear prediction models and ROC analysis. T12-SMD and L3-SMD in women and T12-SMD and L3-SMI in men show weak but significant (p < 0.05) predictive value for gait speed, after adjusting for subject age and body mass index. The prevalence of abnormal CT SMI at T12 and L3 was 29% and 71%, respectively, corresponding to prevalences of confirmed sarcopenia by EWGSOP2 of 10% and 15%, respectively. The agreement of abnormal SARC-F and FRAIL scale screening and EWGSOP2 confirmed sarcopenia was slight to fair (kappa: 0.20-0.28). CT cutpoints, based on EWGSOP2 criteria for abnormal grip strength or gait speed, are generally lower than cutpoints based on normative population data. Collection of clinical and functional sarcopenia information at the point of imaging care can be accomplished quickly and safely. CT-derived muscle metrics show convergent validity with gait speed. Only a minority of subjects with low CT metrics have confirmed sarcopenia by EWGSOP2 definition.

Association of adipose tissue and skeletal muscle metrics with overall survival and postoperative complications in soft tissue sarcoma patients: an opportunistic study using computed tomography.

To determine the relationship between adipose tissue and skeletal muscle measurements on computed tomography (CT) and overall survival and major postoperative complications in patients with soft-tissue sarcoma (STS). The retrospective study included 137 STS patients (75 men, 62 women; mean age, 53 years, SD 17.7; mean BMI, 28.5, SD 6.6) who had abdominal CT exams. On a single CT image, at the L4 pedicle level, measurements of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and skeletal muscle area and attenuation were obtained using clinical PACS and specialized segmentation software. Clinical information was recorded, including STS characteristics (size, depth, grade, stage, and site), overall survival, and postoperative complications. The relationships between CT metrics and survival were analyzed using Cox proportional hazard models and those between CT metrics and postoperative complications using logistic regression models. There were 33 deaths and 41 major postoperative complications. Measured on clinical PACS, the psoas area (P=0.003), psoas index (P=0.006), psoas attenuation (P=0.011), and total muscle attenuation (P=0.023) were associated with overall survival. Using specialized software, psoas attenuation was also associated with overall survival (P=0.018). Adipose tissue metrics were not associated with survival or postoperative complications. In STS patients, CT-derived muscle size and attenuation are associated with overall survival. These prognostic biomarkers can be obtained using specialized segmentation software or routine clinical PACS.

Abstract P462: Myosteatosis: Differences in Association With Type 2 Diabetes by Anatomical Location

Background: CT-derived muscle density (MD) reflects the degree of adiposity in muscle (i.e., myosteatosis) with lower MD indicating greater adiposity. Previous research indicates lower MD is associated with increased risk of type 2 diabetes (T2D). However, few studies have compared the association of simultaneously measured MD by anatomic location. The relationship between myosteatosis and cardiometabolic health may differ by body site and influence which location(s) is most useful for risk assessment. We investigated potential differential relationships between T2D and MD of the locomotor muscles of the abdomen (psoas), thigh, and calf among 539 African Caribbean men from Tobago. Methods: Men were aged 50-91 years (mean 64.4 years, mean BMI 27.5 kg/m 2 ). Calf MD was measured at 66% of calf length using peripheral quantitative CT; calf MD was defined as the ratio of muscle mass to cross-sectional muscle area. Psoas MD was measured in the abdomen (between L3/L4) and thigh MD was measured in the mid-thigh using CT; for these, MD was defined as the average muscle attenuation across each site. MDs were converted to per-SD units for comparability. T2D was defined as a fasting serum glucose level of ≥126 mg/dL or currently taking antidiabetic medication. Results: Psoas and thigh MDs were more highly correlated (r = 0.70) than psoas and calf (r = 0.33) or thigh and calf (r = 0.53) MDs, and calf MD was moderately correlated with BMI (r = -0.38) compared to lower BMI correlations for thigh (r = -0.18) or psoas (r = -0.16) MDs (all significant p &lt; 0.05). After age and lifestyle factor adjustment (Table), a 1-SD lower MD of the thigh or calf was significantly associated with higher odds of T2D. Additional adjustment for BMI completely attenuated the association with T2D for thigh MD, but not calf MD. Conclusion: In our study of African Ancestry men, only calf MD was associated with higher odds of T2D independent of BMI and other muscle groups. Longitudinal studies are needed to better characterize specific muscle myosteatosis and metabolic abnormalities.

437P - Correlation between bio-impedance analysis and abdominal CT scan to diagnose decreased muscle mass in adult cancer patients

BackgroundSarcopenia, characterized by a decline of skeletal muscle plus low muscle strength and/or physical performance, has emerged to be an important prognostic factor for advanced cancer patients. Sarcopenia is diagnosed if there is decreased muscle mass and either decreased muscle function or physical activity. The diagnostic tools for evaluating muscle mass in cancer patients was using muscle index derived from abdominal CT scan. However, the practicability of using CT scan for screening decreased muscle mass has been questioned. Until know there is limited data diagnostic value of Bio-impedance analysis (BIA) in cancer patients. The aim of this study is to know the correlation between BIA and abdominal CT scan to diagnose decreased muscle mass in cancer patients. MethodsThis cross-sectional study included adult cancer patients who underwent abdominal CT scans in purpose for diagnostic. BIA was performed in the same day when CT-scan was performed. CT-scans was analyzed using special software. BIA was performed using standing-posture 2-electrode BIA device BC-418 (BIA, Tanita Corp, Tokyo, Japan). Height adjusted appendicular skeletal muscle mass (ASM) was calculated from BIA. Height adjusted skeletal muscle Index (SMI) was performed from a single cross-sectional CT image (slice) at third lumbar (L3) for abdominal skeletal muscle area. We calculated Pearson’s r correlation coefficient between two parameters. ResultsA total of 39 patients were included. Twenty-eight (71.8%) patients were female. The mean of age was 51.18 +13.83 years old. Several type of cancer such as breast, lung, gastrointestinal and genitourinary cancer were included. Eleven (28.2%) patients were in advanced stage. Mean of height adjusted BIA was 6.60 + 0.98 kg/m2. Mean of height adjusted muscle mass was 42.25 + 7.57 cm2/m2. BIA and CT-derived muscle were moderately correlated (r = 0.72, p < 0.001). ConclusionsThis study showed that BIA- and CT-derived muscle mass was moderately correlated in adult cancer patients. Further research is needed to confirm this result. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

SUN-PO187: Relationship Between BIA- and CT-Derived Muscle Mass in Medical Ill Patients

SUN-PO187: Relationship Between BIA- and CT-Derived Muscle Mass in Medical Ill Patients

Identifying critically ill patients with low muscle mass: Agreement between bioelectrical impedance analysis and computed tomography

Low muscle mass and -quality on ICU admission, as assessed by muscle area and -density on CT-scanning at lumbar level 3 (L3), are associated with increased mortality. However, CT-scan analysis is not feasible for standard care. Bioelectrical impedance analysis (BIA) assesses body composition by incorporating the raw measurements resistance, reactance, and phase angle in equations. Our purpose was to compare BIA- and CT-derived muscle mass, to determine whether BIA identified the patients with low skeletal muscle area on CT-scan, and to determine the relation between raw BIA and raw CT measurements. This prospective observational study included adult intensive care patients with an abdominal CT-scan. CT-scans were analysed at L3 level for skeletal muscle area (cm2) and skeletal muscle density (Hounsfield Units). Muscle area was converted to muscle mass (kg) using the Shen equation (MMCT). BIA was performed within 72h of the CT-scan. BIA-derived muscle mass was calculated by three equations: Talluri (MMTalluri), Janssen (MMJanssen), and Kyle (MMKyle). To compare BIA- and CT-derived muscle mass correlations, bias, and limits of agreement were calculated. To test whether BIA identifies low skeletal muscle area on CT-scan, ROC-curves were constructed. Furthermore, raw BIA and CT measurements, were correlated and raw CT-measurements were compared between groups with normal and low phase angle. 110 patients were included. Mean age 59±17 years, mean APACHE II score 17 (11-25); 68% male. MMTalluri and MMJanssen were significantly higher (36.0±9.9kg and 31.5±7.8kg, respectively) and MMKyle significantly lower (25.2±5.6kg) than MMCT (29.2±6.7kg). For all BIA-derived muscle mass equations, a proportional bias was apparent with increasing disagreement at higher muscle mass. MMTalluri correlated strongest with CT-derived muscle mass (r=0.834, p<0.001) and had good discriminative capacity to identify patients with low skeletal muscle area on CT-scan (AUC: 0.919 for males; 0.912 for females). Of the raw measurements, phase angle and skeletal muscle density correlated best (r=0.701, p<0.001). CT-derived skeletal muscle area and -density were significantly lower in patients with low compared to normal phase angle. Although correlated, absolute values of BIA- and CT-derived muscle mass disagree, especially in the high muscle mass range. However, BIA and CT identified the same critically ill population with low skeletal muscle area on CT-scan. Furthermore, low phase angle corresponded to low skeletal muscle area and -density. ClinicalTrials.gov (NCT02555670).

The relationship between muscle protein content and CT-derived muscle radio-density in patients with upper GI cancer

Cancer cachexia is a multifactorial syndrome characterized by skeletal muscle loss. Cross-sectional analysis of CT scans is a recognized research method for assessing skeletal muscle volume. However, little is known about the relationship between CT-derived estimates of muscle radio-density (SMD) and muscle protein content. We assessed the relationship between CT-derived body composition variables and the protein content of muscle biopsies from cancer patients. Rectus abdominis biopsies from cancer patients (n=32) were analysed for protein content and correlated with phenotypic data gathered using CT body composition software. Skeletal muscle protein content varied widely between patients (median μg/mg wet weight=89.3, range 70-141). There was a weak positive correlation between muscle protein content and SMD (r=0.406, p=0.021), and a weak positive correlation between protein content and percentage weight change (r=0.416, p=0.018). The protein content of skeletal muscle varies widely in cancer patients and cannot be accurately predicted by CT-derived muscle radio-density.

Validation of Bedside Ultrasound of Muscle Layer Thickness of the Quadriceps in the Critically Ill Patient (VALIDUM Study).

In critically ill patients, muscle atrophy is associated with long-term disability and mortality. Bedside ultrasound may quantify muscle mass, but it has not been validated in the intensive care unit (ICU). Here, we compared ultrasound-based quadriceps muscle layer thickness (QMLT) with precise quantifications of computed tomography (CT)-based muscle cross-sectional area (CSA). Patients ≥18 years old with abdominal CT scans performed for clinical reasons were recruited from 9 ICUs for an ultrasound assessment of the quadriceps. CT scans of the third lumbar vertebra, performed <24 hours before or <72 hours after ICU admission, were analyzed for CSA. Low muscularity was defined as 170 cm2 for men and 110 cm2 for women. The ultrasound probe was maximally compressed against the skin and QMLT was measured on 2 sites of each quadriceps <72 hours of the CT scan. Mean CT-derived muscle CSA was 109 ± 25 cm2 for women and 168 ± 37 cm2 for men, where 58% of patients exhibited low muscularity; only 2.7% patients were underweight according to body mass index. QMLT was positively correlated with CT CSA ( r = 0.45, P < .001). Based on logistic regression to predict low muscularity, QMLT independently generated a concordance index ( c) of 0.67 ( P < .002), which increased to 0.77 ( P < .001) when age, sex, body mass index, Charlson Comorbidity Index, and admission type (surgical vs medical) were added. Our results suggest that QMLT alone with our current protocol may not accurately identify patients with low muscle mass.

OR006: The Relationship Between Bia- and CT-Derived Muscle Mass in Critically Ill Patients

OR006: The Relationship Between Bia- and CT-Derived Muscle Mass in Critically Ill Patients