Predictors of visceral and subcutaneous adipose tissue and muscle density: The ShapeUp! Kids study.

BACKGROUND AND AIMS: Body fat distribution, i.e., visceral (VAT), subcutaneous adipose tissue (SAT) and intramuscular fat, is important for disease prevention, but sex and ethnic differences are not well understood. Our aim was to identify anthropometric, demographic, and lifestyle predictors for these outcomes. METHODS AND RESULTS: The cross-sectional ShapeUp!Kids study was conducted among five ethnic groups aged 5-18 years. All participants completed questionnaires, anthropometric measurements, and abdominal MRI scans. VAT and SAT areas at four lumbar levels and muscle density were assessed manually. General linear models were applied to estimate coefficients of determination (R2) and to compare the fit of VAT and SAT prediction models. After exclusions, the study population had 133 male and 170 female participants. Girls had higher BMI-z scores, waist circumference (WC), and SAT than boys but lower VAT/SAT and muscle density. SAT, VAT, and VAT/SAT but not muscle density differed significantly by ethnicity. R2 values were higher for SAT than VAT across groups and improved slightly after adding WC. For SAT, R2 increased from 0.85 to 0.88 (girls) and 0.62 to 0.71 (boys) when WC was added while VAT models improved from 0.62 to 0.65 (girls) and 0.57 to 0.62 (boys). VAT values were significantly lower among Blacks than Whites with little difference for the other groups. CONCLUSION: This analysis in a multiethnic population identified BMI-z scores and WC as the major predictors of MRI-derived SAT and VAT and highlights the important ethnic differences that need to be considered in diverse populations.

Effect of musculature on mortality, a retrospective cohort study.

BACKGROUND: While often life-saving, treatment for head and neck cancer (HNC) can be debilitating resulting in unplanned hospitalization. Hospitalizations in cancer patients may disrupt treatment and result in poor outcomes. Pre-treatment muscle quality and quantity ascertained through diagnostic imaging may help identify patients at high risk of poor outcomes early. The primary objective of this study was to determine if pre-treatment musculature was associated with all-cause mortality. METHODS: Patient demographic and clinical characteristics were abstracted from the cancer center electronic database (n = 403). Musculature was ascertained from pre-treatment CT scans. Propensity score matching was utilized to adjust for confounding bias when comparing patients with and without myosteatosis and with and without low muscle mass (LMM). Overall survival (OS) was evaluated using the Kaplan-Meier method and Cox multivariable analysis. RESULTS: A majority of patients were male (81.6%), white (89.6%), with stage IV (41.2%) oropharyngeal cancer (51.1%) treated with definitive radiation and chemotherapy (93.3%). Patients with myosteatosis and those with LMM were more likely to die compared to those with normal musculature (5-yr OS HR 1.55; 95% CI 1.03-2.34; HR 1.58; 95% CI 1.04-2.38). CONCLUSIONS: Musculature at the time of diagnosis was associated with overall mortality. Diagnostic imaging could be utilized to aid in assessing candidates for interventions targeted at maintaining and increasing muscle reserves.

Fatty Liver Index and Skeletal Muscle Density.

Accumulation of fat in the liver and skeletal muscle is associated with obesity and poor health outcomes. Liver steatosis is a characteristic of non-alcoholic fatty liver disease (NAFLD) and myosteatosis, of poor muscle quality in sarcopenia. In this study of 403 men (33-96 years), we investigated associations between the fatty liver index (FLI) and muscle density, as markers of fat accumulation in these organs. We also investigated associations between the FLI and parameters of sarcopenia, including DXA-derived appendicular lean mass (ALM) and handgrip strength by dynamometry. Muscle density was measured using pQCT at the radius and tibia. FLI was calculated from BMI, waist circumference, and levels of triglycerides and gamma-glutamyltransferase. There was a pattern of decreasing muscle density across increasing quartiles of FLI. After adjusting for age and lifestyle, mean radial muscle density in Q4 was 2.1% lower than Q1 (p < 0.001) and mean tibial muscle density was 1.8% lower in Q3 and 3.0% lower in Q4, compared to Q1 (p = 0.022 and < 0.001, respectively). After adjusting for age and sedentary lifestyle, participants in the highest FLI quartile were sixfold more likely to have sarcopenia. In conclusion, our results suggest that fat accumulation in the liver co-exists with fat infiltration into skeletal muscle.

Aerobic fitness and muscle density play a vital role in postoperative complications in colorectal cancer surgery.

BACKGROUND AND OBJECTIVES: To assess the association of preoperative aerobic fitness and body composition variables with a patient's resilience to the development and impact of postoperative complications after elective colorectal cancer (CRC) surgery. METHODS: Preoperative aerobic fitness was assessed by steep ramp test performance. Preoperative body composition was assessed by muscle mass and density determined from preoperative computed tomography scan analysis at the L3-level. Complication development and severity was graded according to Clavien-Dindo. Complication impact was assessed by the time to recovery of physical functioning after complications. Multivariable logistic regression analyses adjusted for age, sex, comorbidities and tumour location was performed. RESULTS: Of 238 included patients, 96 (40.3%) developed postoperative complications. Better preoperative aerobic fitness decreased the likelihood to develop complications, independent of muscle mass (odds ratio [OR]: 0.55, 95% confidence interval [CI]: 0.35-0.85) or muscle density (OR: 0.57, 95% CI: 0.36-0.89). A prolonged time to recovery following complications was associated with lower preoperative muscle density (OR: 4.14, 95% CI: 1.28-13.41), independent of aerobic fitness. CONCLUSIONS: Lower aerobic fitness increases the risk of complication development, while low muscle density seems associated with a prolonged recovery from complications. Aerobic fitness and muscle density could be valuable additives to preoperative risk assessment.

Is CT-based body composition associated with long-term chemotherapy-induced peripheral neuropathy in colorectal cancer survivors?

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect among colorectal cancer (CRC) survivors, and the severity is mainly dependent on the chemotherapy dose. Nowadays, chemotherapy dose is based on body surface area, while determination based on more accurate measures of body composition may be better. This study aimed to investigate the association between body composition and long-term CIPN among CRC survivors 2-11 years after diagnosis. METHODS: Data from CRC survivors from the population-based PROFILES registry were used. Survivors were included when they received chemotherapy, filled in the EORTC QLQ-CIPN20, and had a computed tomography (CT) scan at diagnosis (n = 202). Total, sensory, motor, and autonomic CIPN were based upon the EORTC QLQ-CIPN20. The abdominal CT scans were used to determine skeletal muscle index (SMI), skeletal muscle density (SMD), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT). Logistic regression was used to analyze the association between CIPN outcomes and body composition variables. RESULTS: CIPN was experienced by 64% of the CRC survivors several years after chemotherapy. More SAT was associated with a higher odds of reporting total CIPN (OR = 1.01 95% CI 1.00-1.01, p = 0.01), motor CIPN (OR = 1.01 95% CI 1.00-1.01, p = 0.01), and sensory CIPN (OR = 1.01 95% CI 1.00-1.01, p = 0.04). No associations of other body composition parameters with CIPN were observed. CONCLUSION: Only SAT was associated with total, motor, and sensory CIPN. Based on these results, we cannot conclude that determining the chemotherapy dose based on body composition is preferred over determining the chemotherapy dose based on body surface to prevent CIPN. More research is needed to assess associations of body composition with CIPN, a common side effect of chemotherapy.

Computed tomography-based paravertebral muscle density predicts subsequent vertebral fracture risks independently of bone mineral density in postmenopausal women following percutaneous vertebral augmentation.

BACKGROUND: The risk of subsequent vertebral fractures (SVF) after the primary vertebral fracture cannot be explained by lower bone mineral density (BMD) alone. Computed tomography (CT) measurements of paravertebral muscle density (PMD) are recognized radiographic markers used to predict physical function, fragile fractures. AIMS: This study aims to investigate the relationship between PMD and the risk of SVF in cohorts of postmenopausal women, and to determine if combining both PMD and BMD measures derived from CT can improve the accuracy of predicting SVF. METHODS: This study enrolled 305 postmenopausal women between the ages of 50 and 88 for 3 years of follow-up studies. Trabecular attenuation (Hounsfield units, HU) was measured at L1 level and muscle attenuation of paravertebral muscle at L3 level on preoperative lumbar CT scans to determine the L1 BMD and L3 PMD. Kaplan-Meier analysis was applied to evaluate SVF-free survival. The hazard ratios (HRs) of PMD for SVF events were estimated with the Cox proportional hazards model. The predictive values of L1 BMD and L3 PMD for SVF were quantified using the Receiver-Operating Characteristic (ROC) curve. RESULT: During the 3 years of follow-up studies, 88 patients (28.9%) suffered an SVF. ROC curve analysis demonstrated that an L3 PMD threshold of 32 HU had a sensitivity of 89.8% and a specificity of 62% for the prediction of SVF. Kaplan-Meier analysis showed that L3 PMD ≤ 32 HU was significantly associated with lower SVF-free survival (p < 0.001; log-rank test). After adjusting for age, BMI, diabetes, postoperative osteoporosis treatment, handgrip strength, L1 BMD, multivariate analyses also indicated a persistent modest effect of L3 PMD on SVF-free survival. The area under the ROC curve of L3 PMD and L1 BMD, combined to predict the risk of SVF, was 0.790, which was significantly higher than the value for L1 BMD alone (0.735). L3 PMD and L1 BMD significantly improved the accuracy of SVF risk prediction compared with L1 BMD alone, which was confirmed by reclassification improvement measures. The inclusion of handgrip strength and postoperative osteoporosis treatment in the model further improved SVF prediction accuracy, and PMD remained significant in the model. CONCLUSION: Decreased L3 PMD is an independent risk predictor of SVF. Combined CT-based L1 BMD and L3 PMD can significantly improve the accuracy of predicting the risk of SVF in postmenopausal women who have suffered prior osteoporotic vertebral fractures.

Evaluation of skeletal muscle mass as a predictor of prognosis in patients treated in hospital for COVID-19 infection.

SUBJECTIVE: Skeletal muscle indexes are known to be one of the important prognostic indicators in many clinical situations. This study aims to evaluate the effects of laboratory values and muscle mass measures such as skeletal muscle area (SMA), skeletal muscle index (SMI), skeletal muscle density (SMD) and skeletal muscle gauge (SMG) obtained from the 12th thoracic vertebra (T12) level of patients hospitalized for COVID-19 infection on prognosis. METHODS: The patients' age, comorbidity index (CCI) scores, gender, anthropometric criteria such as height, weight, and BMI, laboratory values, development of NIMV and IC need during follow-up, length of hospital stay, and hospital mortality were retrospectively screened. The relationship between clinical and laboratory variables, SMA, SMI, SMD, and SMG values, and patient outcomes such as the need for non-invasive mechanical ventilation (NIMV), need for intensive care, and mortality was investigated using multivariate logistic regression analysis. RESULTS: It was shown in multilinear regression analysis that T12SMD (ß=-0.254; p=0.036), albumin (ß=-0.465; p=0.005), and procalcitonin values (ß=-0.292; p=0.026) were independent risk factors on mortality for intensive care in patients hospitalized due to COVID-19 infection. T12SMD has been shown to be significantly associated with various negative outcomes such as mortality, need for NIMV, and need for intensive care independently of body mass index (BMI) in our study (Tab. 5, Fig. 2, Ref. 25).

Clinical significance of skeletal muscle density and sarcopenia in patients with pancreatic cancer undergoing first-line chemotherapy: a retrospective observational study.

BACKGROUND: To investigate the clinical impact of sarcopenia and skeletal muscle density (SMD) among patients with metastatic pancreatic adenocarcinoma who underwent palliative first line gemcitabine-based chemotherapy. METHODS: A total of 330 patients treated with first line gemcitabine-based chemotherapy between January 2010 and March 2017 were included. CT scans before chemotherapy and after 8±2 weeks were evaluated. The L3 skeletal muscle index (SMI) was used to detect sarcopenia and calculated as the total area of the L3 skeletal muscle divided by the height-squared (cm2/m2). SMD was quantified as the mean muscle radiation attenuation of the muscle cross-sectional area across the L3 vertebral body level and was assessed between - 29 and + 150 Hounsfield units. RESULTS: A SMI to SMD comparison revealed a positive correlation (R2 = 0.058, P < 0.001). Compared with high SMD, the risks of low SMI were 1.516 (95% confidence interval [CI]: 1.164-1.973) among patients with low SMD. Kaplan-Meier analysis showed that the low SMD was related to poor overall survival (OS, median, 6.1 versus [vs.] 7.9 months, P = 0.010). Multivariate analysis using Cox regression showed that low SMI (hazard ratio [HR]: 1.35, 95% CI: 1.03-1.78, P = 0.032) and low SMD (HR: 1.45, 95% CI: 1.09-1.93, P = 0.011) were poor prognostic factors for OS, respectively. Co-presence of low SMI and low SMD had more powerful prognostic implication for OS (HR: 1.58, 95% CI: 1.12-2.23, P = 0.010). Grade 3 or higher toxicity of chemotherapy was more frequently observed in patients who have a low SMI (43% vs. 59%, P = 0.019) and low SMD (44% vs. 60%, P = 0.023). OS was not related to SMD status among patients who were chemotherapy responders (complete or partial responses). However, among non-responders (stable or progressive disease), low SMD groups had significantly poorer OS in comparison with high SMD groups (median, 5.6 vs 7.4 months, P = 0.006). CONCLUSIONS: Sarcopenia and SMD status can be considered a prognostic factor in patients with metastatic pancreatic adenocarcinoma who received palliative first line gemcitabine-based chemotherapy. Severe chemotherapy toxicity occurred in the sarcopenia and low SMD groups. Our data suggest that a comprehensive assessment of skeletal muscle parameters may be more useful prognostic factors.

Computed Tomography-Derived Skeletal Muscle Radiodensity Predicts Peak Weight-Corrected Jump Power in Older Adults: The Korean Urban Rural Elderly (KURE) Study.

Computed tomography (CT)-derived skeletal muscle area (SMA) and skeletal muscle radiodensity (SMD) reflect distinctive quantitative and qualitative characteristics of skeletal muscles. However, data on whether CT-based muscle parameters, especially SMD, can predict muscle function is limited. In a prospective cohort, 1523 community-dwelling older adults who underwent abdominal CT scans and the countermovement two-legged jumping test on a ground reaction force platform were analyzed (mean age 74.7 years, 65.1% women). SMA and SMD were measured at third lumbar vertebra level (L3). Individuals with low jump power (peak weight-corrected jump power < 23.8 W/kg in men and < 19.0 W/kg in women using clinically validated threshold) were older; had lower SMA, SMD, and maximal grip strength values; and had lower chair rise test and timed up and go test performance than those without low jump power. SMD was positively associated with peak weight-corrected jump power (adjusted ß = 0.33 and 0.23 per 1 HU increase in men and women, respectively, p < 0.001). One HU decrement in SMD was associated with 10% elevated odds of low jump power (adjusted OR [aOR] 1.10, p < 0.001) after adjusting for age, sex, height, inflammation, and insulin resistance markers, whereas the association of SMA with low jump power was attenuated (aOR 1.00, p = 0.721). SMD showed better discrimination for low jump power than SMA (AUC 0.699 vs. 0.617, p < 0.001), with additional improvement when added to SMA and conventional risk factors (AUC 0.745 to 0.773, p < 0.001). Therefore, CT-measured L3 SMD can be a sensitive surrogate marker for muscle function along with SMA in older adults, which merits further investigation.

Skeletal Muscle Density and Cognitive Function: A Cross-Sectional Study in Men.

We aimed to investigate cross-sectional associations between skeletal muscle density, a proxy measure for fatty infiltration into muscle, and cognition. Contributions from body fat mass, systemic inflammation and lifestyle were explored, as these factors have been identified in both muscle and cognitive deterioration. For 281 men (60-95 year) from the Geelong Osteoporosis Study, radial and tibial muscle density were measured using peripheral quantitative computed tomography. Body fat and appendicular lean mass were measured using dual-energy X-ray absorptiometry. Cognitive function was assessed for psychomotor function (DET), visual identification/attention (IDN), visual learning (OCL) and working memory (OBK) (CogState Brief Battery). Composite scores signified overall cognitive function (OCF). Higher scores represent poorer performance except for OCL and OCF. Regression analyses examined associations between muscle density and cognition; potential confounders included age, muscle cross-sectional area (CSA), body composition, lifestyle and serum markers of inflammation. Negative associations with age were evident for muscle density, all cognitive domains and OCF. Muscle density at both sites was positively associated with DET, OCL and OCF. After adjustment for age, the association persisted for DET (radius: B = - 0.006, p = 0.02; tibia: B = - 0.003, p = 0.04) and OCL (radius B = + 0.004, p = 0.02; tibia: B = + 0.005, p < 0.001). At the radius, further adjustment for serum TNF-α explained the association between muscle density (B = - 0.002, p = 0.66) and DET. Education and physical activity contributed to the model for radial muscle density and DET. There were no contributions from muscle CSA, appendicular lean mass, body fat mass, other markers of inflammation or other potential confounders. At the tibia, the association between muscle density and DET (B = - 0.003, p = 0.04) was independent of TNF-α. There was an age-adjusted association between muscle density and OCL at both sites (radius: B = + 0.004, p = 0.02; tibia: B = + 0.005, p < 0.001). None of the potential confounders contributed to the models. Muscle density was associated with cognitive function in the DET and OCL domains. However, there was little evidence that this was explained by inflammation or body fat mass. No associations were identified between muscle density and IDN or OBK.

Decreased skeletal muscle density is an independent predictor of mortality in necrotizing pancreatitis- A single tertiary center experience in 507 patients.

BACKGROUND AND AIMS: Necrotizing pancreatitis has a variable clinical course and it is essential to identify determinants associated with high risk of mortality and poor clinical outcomes. The aim of this study is to evaluate the association between CT-assessed body composition parameters such as visceral fat area (VFA), skeletal muscle index (SMI) and skeletal muscle density (SMD) and inpatient mortality in NP patients. Secondary outcomes include organ failure on admission, persistent organ failure, length of stay (LOS), need for ICU admission, need for endoscopic, percutaneous or surgical interventions for NP and 30-day unplanned readmission. METHODS: All NP patients managed at a single center between 2009 and 2019 with a CT scan within a week of admission were included. SMI, SMD and VFA was calculated from CT imaging at the third lumbar vertebra and multivariable analysis was performed after correcting for age, sex, BMI, ASA classification, multi- organ failure on admission to determine independent association with inpatient mortality and secondary outcomes. RESULTS: 507 NP patients [males = 349 (68.8%), median age 53 (IQR 37-65) years were included in this study. The lowest tertile SMD was independently associated with inpatient mortality on multivariable analysis: adjusted OR 3.36 (1.57-7.2), P = 0.002. The lowest SMI tertile and highest VFA tertile were not independently associated with mortality. Lowest tertile SMD was significantly associated with persistent organ failure (OR 2.01, 95% CI 1.34-3.01, p = 0.001), need for percutaneous drainage (OR 1.84, 95% CI 1.21-2.8, p = 0.004), need for ICU admission (OR 2.32, 95% CI 1.59-3.38, p < 0.0001) and LOS. CONCLUSION: Low SMD was independently associated with in-hospital mortality in NP patients and can be usefully incorporated in CT based predictive scoring models as a prognostic marker.

Low preoperative skeletal muscle density is predictive for negative postoperative outcomes in older women with ovarian cancer.

OBJECTIVE: To determine the predictive value of lumbar skeletal muscle mass and density for postoperative outcomes in older women with advanced stage ovarian cancer. METHODS: A multicenter, retrospective cohort study was performed in women ≥ 70 years old receiving surgery for primary, advanced stage ovarian cancer. Skeletal muscle mass and density were assessed in axial CT slices on level L3. Low skeletal muscle mass was defined as skeletal muscle index < 38.50 cm2/m2. Low skeletal muscle density was defined as one standard deviation below the mean (muscle attenuation < 22.55 Hounsfield Units). The primary outcome was any postoperative complication ≤ 30 days after surgery. Secondary outcomes included severe complications, infections, delirium, prolonged hospital stay, discharge destination, discontinuation of adjuvant chemotherapy and mortality. RESULTS: In analysis of 213 patients, preoperative low skeletal muscle density was associated with postoperative complications ≤ 30 days after surgery (Odds Ratio (OR) 2.83; 95% Confidence Interval (CI) 1.41-5.67), severe complications (OR 3.01; 95%CI 1.09-8.33), infectious complications (OR 2.79; 95%CI 1.30-5.99) and discharge to a care facility (OR 3.04; 95%CI 1.16-7.93). Preoperative low skeletal muscle mass was only associated with infectious complications (OR 2.32; 95%CI 1.09-4.92). In a multivariable model, low skeletal muscle density was of added predictive value for postoperative complications (OR 2.57; 95%CI 1.21-5.45) to the strongest existing predictor functional impairment (KATZ-ADL ≥ 2). CONCLUSION: Low skeletal muscle density, as a proxy of muscle quality, is associated with poor postoperative outcomes in older patients with advanced stage ovarian cancer. These findings can contribute to postoperative risk assessment and clinical decision making.

Low skeletal muscle density combined with muscle dysfunction predicts adverse events after adult cardiovascular surgery.

BACKGROUND AND AIMS: Although muscle dysfunctions are widely known as a poor prognostic factor in patients with cardiovascular disease, no study has examined whether the addition of low skeletal muscle density (SMD) assessed by computed tomography (CT) to muscle dysfunctions is useful. This study examined whether SMDs can strengthen the predictive ability of muscle dysfunctions for adverse events in patients who underwent cardiovascular surgery. METHODS AND RESULTS: We retrospectively reviewed 853 patients aged ≥40 years who had preoperative CT for risk management purposes and who measured muscle dysfunctions (weakness: low grip strength and slowness: slow gait speed). Low SMD based on transverse abdominal CT images was defined as a mean Hounsfield unit of the psoas muscle <45. All definitions of muscle dysfunction (weakness only, slowness only, weakness or slowness, weakness and slowness), the addition of SMDs was shown to significantly improve the continuous net reclassification improvement and integrated discrimination improvement for adverse events in all analyses (p < 0.05). Low SMDs combined with each definition of muscle dysfunction had the highest risk of all-cause death (hazard ratio: lowest 3.666 to highest 6.002), and patients with neither low SMDs nor muscle dysfunction had the lowest risk of all-cause and cardiovascular-related events. CONCLUSION: The addition of SMDs consistently increased the predictive ability of muscle dysfunctions for adverse events. Our results suggest that when CT is performed for any clinical investigation, the addition of the organic assessment of skeletal muscle can strengthen the diagnostic accuracy of muscle wasting.

Peripheral Volumetric Muscle Area and Total Body Volume in Postmenopausal Women With Rheumatoid Arthritis.

The effect of rheumatoid arthritis (RA) on peripheral muscle parameters is not completely understood. This study aimed to elucidate the influence of RA on peripheral muscle area and whole body skeletal muscle mass index (SMI) using peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in postmenopausal women. This cross-sectional study included 54 postmenopausal women with RA and 86 healthy controls. Peripheral quantitative computed tomography and dual-energy X-ray absorptiometry were used to measure the muscle cross-sectional area and skeletal muscle mass. Muscle strength was assessed using a handheld dynamometer. Additionally, the effects of RA on muscle area and density as well as the bone / muscle area ratio were analyzed using multivariate models. The muscle area index of the thigh and forearm were correlated between both groups (RA: r = 0.357, p = 0.030; and healthy controls: r = 0.608, p < 0.001) and each index correlated with SMI in RA and healthy controls (p < 0.001). Bone / muscle area ratio correlated between forearms and thighs in health controls only (r = 0.547, p < 0.001). The RA group had a decreased thigh muscle area (p = 0.014); the fat area and fat muscle area ratio at the thigh and forearm were significantly increased (all p < 0.001), as well as thigh bone / muscle area ratio (p = 0.015). The RA group also had significantly lower forearm muscle density (p < 0.001). A sensitivity analysis excluding those on bisphosphonates led to similar results. Independent of RA, the thigh and forearm muscle area correlate with each other and with SMI. Differences in the bone / muscle ratio between RA and healthy controls may indicate regional muscle effects of inflammation and inactivity.

The Assessment of Skeletal Muscle and Cortical Bone by Second-generation HR-pQCT at the Tibial Midshaft.

BACKGROUND: Peripheral quantitative computed tomography (pQCT) is the current densitometric gold-standard for assessing skeletal muscle at the 66% proximal tibia site. High resolution peripheral quantitative computed tomography (HR-pQCT) is a leading technology for quantifying bone microarchitecture at the distal extremities, and with the second-generation HR-pQCT it is possible to measure proximal limb sites. Therefore, the objectives of this study were to: (1) assess the feasibility of using HR-pQCT to assess skeletal muscle parameters at the 66% proximal tibia site, and (2) test HR-pQCT skeletal muscle measurement reproducibility at this site. METHODS: Adult participants (9 males; 7 females; ages 31-75) received 1 pQCT scan and 2 HR-pQCT scans at the 66% proximal site of the nondominant tibia. Participants were repositioned between HR-pQCT scans to test reproducibility. HR-pQCT and pQCT scans were analyzed to quantify muscle cross-sectional area (CSA) and muscle density. Coefficients of determination and Bland-Altman plots compared muscle parameters between pQCT and HR-pQCT. For short-term reproducibility, root-mean-square of coefficient of variance and least significant change were calculated. RESULTS: HR-pQCT and pQCT measured muscle density and muscle CSA were positively correlated (R2 = 0.66, R2 = 0.95, p < 0.001, respectively). Muscle density was equivalent between HR-pQCT and pQCT; however, there was systematic and directional bias for muscle CSA, such that muscle CSA was 11% lower with HR-pQCT and bias increased with larger muscle CSA. Root-mean-square of coefficient of variance was 0.67% and 0.92% for HR-pQCT measured muscle density and muscle CSA, respectively, while least significant change was 1.4 mg/cm3 and 174.0 mm2 for muscle density and muscle CSA, respectively. CONCLUSION: HR-pQCT is capable of assessing skeletal muscle at the 66% site of the tibia with good precision. Measures of muscle density are comparable between HR-pQCT and pQCT.

Association of body composition with function in women with early breast cancer.

BACKGROUND: Advances in breast cancer research are making treatment options increasingly effective and reducing mortality. Body composition is an example of a prognostic tool that can help personalize breast cancer treatments and further increase their effectiveness. In this study, we examine the association of several body composition measures with comorbidities, physical function, and quality of life. METHODS: This study is a cross-sectional analysis of 99 women with early breast cancer scheduled for chemotherapy. Univariate regression models were used to identify significant associations of body composition metrics with patient demographics, clinical characteristics, measures of physical function, and patient-reported outcomes (PRO)s. Multivariable modeling was used to evaluate associations adjusted for age. RESULTS: Median age was 58 (range 24-83), 27% were non-white, and, 47% were obese (≥ 30 kg/m2). Increasing age was associated with lower Skeletal Muscle Density (SMD) (p = 0.0001), lower Skeletal Muscle Gauge (SMG) (p = 0.0005), and higher Visceral Adipose Tissue (VAT) (p < 0.0001). In patients with a prolonged Timed Up and Go tests (> 14 s), mean VAT was 57.87 higher (p = 0.004), SMD 5.70 lower (p = 0.04), and SMG 325.4 lower (p = 0.02). For each point of higher performance on the Short Physical Performance Battery (SPPB), VAT decreased 12.24 (p = 0.002) and SMD rose 1.22 (p = 0.02). In multivariable analysis adjusting for age, the association of TUG > 14 with higher VAT remained significant (p = 0.02). CONCLUSIONS: Suboptimal body composition prior to treatment is associated poor physical function and may be an indicator of clinical importance.

Low Skeletal Muscle Density Is Associated with Early Death in Patients with Perihilar Cholangiocarcinoma Regardless of Subsequent Treatment.

BACKGROUND: Low skeletal muscle mass is associated with increased postoperative morbidity and worse survival following resection for perihilar cholangiocarcinoma (PHC). We investigated the predictive value of skeletal muscle mass and density for overall survival (OS) of all patients with suspected PHC, regardless of treatment. METHODS: Baseline characteristics and parameters regarding disease and treatment were collected from all patients with PHC from 2002 to 2014. Skeletal muscle mass and density were measured at the level of the third lumbar vertebra on CT. The association between skeletal muscle mass and density with OS was investigated using the Kaplan-Meier method and Cox survival. RESULTS: Median OS in 233 included patients did not differ between those with and without low skeletal muscle mass (p = 0.203), whereas a significantly different median OS (months) was observed between patients with low (HR 7.0, 95% CI 4.7-9.3) and high (HR 12.1, 95% CI 8.1-16.1) skeletal muscle density (p = 0.004). Low skeletal muscle density was independently associated with decreased OS (HR 1.78, 95% CI 1.03-3.07, p = 0.040) within the first 6 months but not after 6 months (HR 0.68, 95% CI 0.44-1.07, p = 0.093), after adjusting for age, tumour size and suspected peritoneal or other distant metastases on imaging. CONCLUSION: A time-dependent effect of skeletal muscle density on OS was found in patients with PHC, regardless of subsequent treatment. Low skeletal muscle density may identify patients at risk for early death.

Quantitative analysis of modified functional muscle-bone unit and back muscle density in patients with lumbar vertebral fracture in Chinese elderly men: a case-control study.

OBJECTIVES: Bone mineral density (BMD) is associated with muscle mass and quality, but little research has been done on functional muscle-bone unit and back muscle density in patients with lumbar vertebral fracture. This study used the "modified functional muscle-bone unit" concept and measured back muscle density to investigate muscle-bone interaction difference between the fracture and control group. METHODS: This was a case-control study. A total of 52 elderly male patients (mean age 75 years) with lumbar vertebral fracture (cases) and 52 control healthy subjects were enrolled. Cross-sectional area (CSA) and density of paravertebral muscle were measured in quantitative computed tomography (QCT) images to represent the muscle mass, while the bone mineral density measured by QCT was used to represent the bone mass. The modified functional muscle-bone unit was calculated as the value of volumetric BMD divided by muscle area. RESULTS: People with vertebral fractures reported significantly lower values in the cross-sectional area and density of paravertebral muscle compared to control group. In the multivariate analysis, BMD (odds ratio, OR = 0.929; 95% confidence intervals, CIs 0.888-0.971), erector muscle density (OR = 0.698; 95% CI 0.547-0.892), and summated muscle CSA (OR = 0.963; 95% CI 0.93-0.991) were independent protective factors for the presence of a fracture. BMD resulted significantly and moderately associated with cross-sectional area and density of paravertebral muscle (r = 0.329-0.396). CONCLUSIONS: There were significant differences between the modified functional muscle-bone unit and back muscle density between the fracture group and control group in elderly men. Lower BMD, loss of muscle mass and density are associated with increased presence of the lumbar vertebral fracture.

Population-based study of age- and sex-related differences in muscle density and size in thoracic and lumbar spine: the Framingham study.

Relative age-related deficit in trunk muscle density was greater in women than men whereas the relative decrease in muscle mass with age was similar in both sexes. The greater muscle fat content and greater age-related fat accumulation among women may contribute to women suffering more functional disabilities than men. INTRODUCTION: A better understanding of the effect of aging on trunk musculature will have implications for physical function, disability, pain, and risk of injury in older adults. Thus, we determined the age- and sex-related differences in muscle density and size of both thoracic and lumbar trunk muscles. METHODS: In this cross-sectional study, muscle density and size were measured from quantitative computed tomography (QCT) scans for 10 trunk muscle groups at different vertebral levels in 250 community-based men and women aged 40 to 90 years from the Framingham Offspring and Third Generation cohorts. RESULTS: Trunk muscles in men were 20-67% larger and had 5-68% higher density than in women. The relative age-related deficits in muscle size were similar in both sexes, and decreased on average by ~ 8% per decade in both sexes. In contrast, women had greater age-related decreases in muscle density than men (- 17% in women, and - 11% in men, p < 0.01). Age-related declines varied by specific muscle, tending to be greater for outer trunk muscles than for paraspinal muscles, but within a given muscle the age-related changes in muscle density and size were similar among spinal levels. CONCLUSION: This comprehensive study of trunk muscle deficits with increasing age may have important implications for physical function, disability, pain, and risk of injury in older adults. The greater levels of mobility impairments with aging in women may in part be explained by greater proportion of intramuscular fat tissue and greater age-related fat accumulation in trunk muscles in women than in men.

Validation of Peripheral Quantitative Computed Tomography-Derived Thigh Adipose Tissue Subcompartments in Young Girls Using a 3 T MRI Scanner.

The ability to assess skeletal muscle adipose tissue is important given the negative clinical implications associated with greater fat infiltration of the muscle. Computed tomography and magnetic resonance imaging (MRI) are highly accurate for measuring appendicular soft tissue and muscle composition, but have limitations. Peripheral quantitative computed tomography (pQCT) is an alternative that investigators find valuable because of its low radiation, fast scan time, and comparatively lower costs. The present investigation sought to assess the accuracy of pQCT-derived estimates of total, subcutaneous, skeletal muscle, intermuscular, and calculated intramuscular adipose tissue areas, and muscle density in the midthigh of young girls using the gold standard, 3 T MRI, as the criterion. Cross-sectional data were analyzed for 26 healthy girls aged 9-12 years. Midthigh soft tissue composition was assessed by both pQCT and 3 T MRI. Mean tissue area for corresponding adipose compartments by pQCT and MRI was compared using t tests, regression analysis, and Bland-Altman plots. Muscle density was regressed on MRI skeletal muscle adipose tissue, intermuscular adipose tissue, and intramuscular adipose tissue, each expressed as a percentage of total muscle area. Correlations were high between MRI and pQCT for total adipose tissue (r2 = 0.98), subcutaneous adipose tissue (r2 = 0.95), skeletal muscle adipose tissue (r2 = 0.83), and intermuscular adipose tissue (r2 = 0.82), and pQCT muscle density correlated well with both MRI skeletal muscle adipose tissue (r2 = 0.70) and MRI intermuscular adipose tissue (r2 = 0.70). There was a slight, but statistically significant underestimation by pQCT for total and subcutaneous adipose tissue, whereas no significant difference was observed for skeletal muscle adipose tissue. Both pQCT-estimated intramuscular adipose tissue and muscle density were weakly correlated with MRI-intramuscular adipose tissue. We conclude that pQCT is a valid measurement technique for estimating all adipose subcompartments, except for intramuscular adipose tissue, for the midthigh region in young/adolescent girls.