Lean Muscle Area Research Articles

Fractal Features of Muscle to Quantify Fatty Infiltration in Aging and Pathology

Fractal Features of Muscle to Quantify Fatty Infiltration in Aging and Pathology

Psoas muscle analysis as a surrogate marker of sarcopenia and frailty: A multicenter analysis of predictive capacities over short- and long-term outcomes after abdominal aortic aneurysm repair.

Several predictive models exist for estimating the postoperative risks of abdominal aortic aneurysm (AAA) repair, although no particular tool has seen widespread use. We present the results of a multicenter, historic cohort study comparing the predictive capacity of the psoas muscle area (PMA), radiodensity (PMD), and lean muscle area (LMA) as surrogate markers of sarcopenia, over short- and long-term outcomes after AAA repair, compared to the mFI-5 and American Society of Anesthesiologists (ASA) scales. Retrospective review was conducted of all consecutive AAA elective repair cases (open or endovascular) in three tertiary-care centers from 2014 to 2019. Cross-sectional PMA, PMD, and LMA at the mid-body of the L3 vertebra were measured by two independent operators in the preoperative computed tomography. Receiver operating characteristic (ROC) curves were used to determine optimal cutoff values. Bivariate analysis, logistic regression, and Cox's proportional hazards models were built to examine the relationship between baseline variables and postoperative mortality, long-term mortality, and complications. 596 patients were included (mean age 72.7 ± 8years, 95.1% male, 66.9% EVAR). Perioperative mortality was 2.3% (EVAR 1.2% vs open repair 4.6%, p = .015), and no independent predictors could be identified in the multivariate analysis. Conversely, an age over 74years old (OR 1.84 95%CI 1.25-2.70), previous heart diseases (OR 1.62 95%CI 1.13-2.32), diabetes mellitus (OR 1.61 95%CI 1.13-2.32), and a PMD value over 66 HU (OR 0.58 95%CI 0.39-0.84) acted as independent predictors of long-term mortality in the Cox's proportional hazards model. Heart diseases (congestive heart failure or coronary artery disease), serum creatinine levels over 1.05mg/dL, and an aneurysm diameter over 60mm were independent predictors of major complications. Surrogate markers of sarcopenia had a poor predictive profile for postoperative mortality after AAA repair in our sample. However, PMD stood out as an independent predictor of long-term mortality. This finding can guide future research and should be confirmed in larger datasets.

Association of maternal temperament and offspring disposition on growth performance.

Animal behavior is complex and varies in definition, depending upon specific traits under observation. Temperament is one component of behavior, that in cattle, is described as the level of fearfulness to a novel or threatening environment. Temperament is a heritable trait which is important since aggressiveness and docility contribute to reproductive success, growth, and carcass quality. We observed maternal temperament at calving and the subsequent influence, if any, on offspring disposition at weaning and their effects collectively on growth performance and carcass traits. Maternal behaviors at calving were observed at four locations within the University of Arkansas system. Cows were assigned a maternal disposition score (MDS) at calving; a scale from 1 to 5 in which aggression decreases. At weaning, calves were assigned a chute score (CS); a scale from 1 to 6 in which aggression increases. Both scoring systems have been previously established. Blood was collected during the 56-d backgrounding period postweaning for blood glucose analysis. Data were analyzed using GLIMMIX procedures of SAS (α = 0.05). The relationship between the two scoring systems was determined with a Pearson correlation (P = 0.22). Animal was the experimental unit and blocked by location for all dependent variables. Location, sex, diet, and MDS were included in the class as covariables for all growth performance and carcass data related to CS. Cows that were more aggressive birthed heavier calves (P < 0.01) compared to indifferent cows. Calves born to cows with either very aggressive or very attentive (MDS of 2 or 3, respectively) scores were heavier upon feedlot entry (P = 0.03) compared to those from indifferent or apathetic cows (MDS of 4 or 5, respectively). Calves defined as nervous and restless (CS of 3 and 2, respectively) were heavier at weaning compared to docile calves (P < 0.01). Restless calves were heavier compared to nervous calves upon arrival and exiting the feedlot (P ≤ 0.01). Calves that were docile at weaning had greater marbling compared to calves that were restless (P ≤ 0.01). Calves that were restless at weaning had greater lean muscle area compared to calves that were nervous (P = 0.05). No definitive relationship was determined between dam and calf temperament. However, the results suggest temperament does impact growth performance and carcass traits but whether the influence comes from the dam or calf temperament, specifically, remains unanswered.

Paraspinal Muscle Health is Related to Fibrogenic, Adipogenic, and Myogenic Gene Expression in Patients with Lumbar Spine Pathology

BackgroundLumbar spine pathology is a common feature of lower back and/or lower extremity pain and is associated with observable degenerative changes in the lumbar paraspinal muscles that are associated with poor clinical prognosis. Despite the commonly observed phenotype of muscle degeneration in this patient population, its underlying molecular mechanisms are not well understood. The aim of this study was to investigate the relationships between groups of genes within the atrophic, myogenic, fibrogenic, adipogenic, and inflammatory pathways and multifidus muscle health in individuals undergoing surgery for lumbar spine pathology.MethodsMultifidus muscle biopsies were obtained from patients (n = 59) undergoing surgery for lumbar spine pathology to analyze 42 genes from relevant adipogenic/metabolic, atrophic, fibrogenic, inflammatory, and myogenic gene pathways using quantitative polymerase chain reaction. Multifidus muscle morphology was examined preoperatively in these patients at the level and side of biopsy using T2-weighted magnetic resonance imaging to determine whole muscle compartment area, lean muscle area, fat cross-sectional areas, and proportion of fat within the muscle compartment. These measures were used to investigate the relationships between gene expression patterns and muscle size and quality.ResultsRelationships between gene expression and imaging revealed significant associations between decreased expression of adipogenic/metabolic gene (PPARD), increased expression of fibrogenic gene (COL3A1), and lower fat fraction on MRI (r = -0.346, p = 0.018, and r = 0.386, p = 0.047 respectively). Decreased expression of myogenic gene (mTOR) was related to greater lean muscle cross-sectional area (r = 0.388, p = 0.045).ConclusionFibrogenic and adipogenic/metabolic genes were related to pre-operative muscle quality, and myogenic genes were related to pre-operative muscle size. These findings provide insight into molecular pathways associated with muscle health in the presence of lumbar spine pathology, establishing a foundation for future research that addresses how these changes impact outcomes in this patient population.

Impact of Total Psoas Area and Lean Muscular Area on Mortality after Endovascular Aortic Aneurysm Repair

Sarcopenia has assumed growing relevance as a morbimortality predictor after major abdominal surgery. The aim of this study is to access total psoas muscle area (TPA) and lean muscle area (LMA) impact in morbimortality after elective endovascular abdominal aortic aneurysm repair (EVAR). Asymptomatic patients submitted to aortic endoprosthesis implantation between January 1, 2014 and December 31, 2018 at our vascular surgery department were retrospectively evaluated. After exclusion criteria were applied, 105 patients were included in the study; preoperative computed tomography scans were evaluated using OSIRIX software (Bernex, Switzerland). Two observers independently calculated TPA at the most caudal level of the L3 vertebra and respective density, therefore calculating LMA. Patients were separated by tertiles with the lowest being considered sarcopenic and with higher muscle steatosis and compared with the higher tertiles. Patient demographics and intraoperative and postoperative period variables were collected. Charlson comorbidity index was calculated and surgical complications classified according to Clavien-Dindo. The intraclass correlation coefficient and Bland-Altman plot were made to characterize interobserver variability. Survival analysis was performed with the Kaplan-Meier method, and differences between survival curves were tested with the log-rank test. The effect of sarcopenia on patient survival was assessed using Cox proportional hazard models. Considering TPA, univariate analyses revealed that patients in the lower tertile had inferior survival (P=0.03), whereas multivariate analyses showed increased likelihood of mortality (P=0.039, hazard ratio (HR) 3.829). For LMA, univariate analyses revealed that patients in the lower tertile had inferior survival (P=0.013), whereas multivariate analyses showed increased likelihood of mortality (P=0.026, HR 4.153). When analyzing patients in the lowest tertile of both TPA and LMA, both univariate (P=0.002) and multivariate (P=0.018, HR 4.166) analyses reveled inferior survival. Our study reveals reduced survival in patients with low TPA and low LMA submitted to elective EVAR; these factors should probably be taken into consideration in the future for preoperative risk evaluation and surgical planning.

Genomic Analysis Using Bayesian Methods under Different Genotyping Platforms in Korean Duroc Pigs.

Simple SummaryThis study investigated the informative regions and the efficiency of genomic predictions for backfat thickness, days to 90 kg body weight, loin muscle area, and lean percentage in Korean Duroc pigs. The several regions of the genome were identified and a significant marker was found near the MC4R gene for growth and production-related traits. No differences in genomic accuracy were identified on the basis of the Bayesian approaches in these four growth and production-related traits. The genomic accuracy is improved by using deregressed estimated breeding values including parental information as a response variable in Korean Duroc pigs.Genomic evaluation has been widely applied to several species using commercial single nucleotide polymorphism (SNP) genotyping platforms. This study investigated the informative genomic regions and the efficiency of genomic prediction by using two Bayesian approaches (BayesB and BayesC) under two moderate-density SNP genotyping panels in Korean Duroc pigs. Growth and production records of 1026 individuals were genotyped using two medium-density, SNP genotyping platforms: Illumina60K and GeneSeek80K. These platforms consisted of 61,565 and 68,528 SNP markers, respectively. The deregressed estimated breeding values (DEBVs) derived from estimated breeding values (EBVs) and their reliabilities were taken as response variables. Two Bayesian approaches were implemented to perform the genome-wide association study (GWAS) and genomic prediction. Multiple significant regions for days to 90 kg (DAYS), lean muscle area (LMA), and lean percent (PCL) were detected. The most significant SNP marker, located near the MC4R gene, was detected using GeneSeek80K. Accuracy of genomic predictions was higher using the GeneSeek80K SNP panel for DAYS (Δ2%) and LMA (Δ2–3%) with two response variables, with no gains in accuracy by the Bayesian approaches in four growth and production-related traits. Genomic prediction is best derived from DEBVs including parental information as a response variable between two DEBVs regardless of the genotyping platform and the Bayesian method for genomic prediction accuracy in Korean Duroc pig breeding.

Fat-free muscle area measured by magnetic resonance imaging predicts overall survival of patients undergoing radioembolization of colorectal cancer liver metastases.

To investigate the clinical potential of fat-free muscle area (FFMA) to predict outcome in patients with liver-predominant metastatic colorectal cancer (mCRC) undergoing radioembolization (RE) with 90Yttrium microspheres. Patients with mCRC who underwent RE in our center were included in this retrospective study. All patients received liver magnetic resonance imaging including standard T2-weighted images. The total erector spinae muscle area and the intramuscular adipose tissue area were measured at the level of the origin of the superior mesenteric artery and subtracted to calculate FFMA. Cutoff values for definition of low FFMA were 3644mm2 in men and 2825mm2 in women. The main outcome was overall survival (OS). For survival analysis, the Kaplan-Meier method and Cox regressions comparing various clinic-oncological parameters which potentially may affect OS were performed. Seventy-seven patients (28 female, mean age 60 ± 11years) were analyzed. Mean time between MRI and the following RE was 17 ± 31days. Median OS after RE was 178days. Patients with low FFMA had significantly shortened OS compared to patients with high FFMA (median OS: 128 vs. 273days, p = 0.017). On multivariate Cox regression analysis, OS was best predicted by FFMA (hazard ratio (HR) 2.652; p < 0.001). Baseline bilirubin (HR 1.875; p = 0.030), pattern of tumor manifestation (HR 1.679; p = 0.001), and model of endstage liver disease (MELD) score (HR 1.164; p < 0.001) were also significantly associated with OS. FFMA was associated with OS in patients receiving RE for treatment of mCRC and might be a new prognostic biomarker for survival prognosis. • Fat-free muscle area (FFMA) as a measure of lean muscle area predicts survival in metastatic colorectal liver cancer following radioembolization. • FFMA can easily be assessed from routine pre-interventional liver magnetic resonance imaging. • FFMA might be a new promising biomarker for assessment of sarcopenia.

The Growth Hormone Releasing Hormone Analogue, Tesamorelin, Decreases Muscle Fat and Increases Muscle Area in Adults with HIV.

Tesamorelin, a growth hormone-releasing hormone analogue, decreases visceral adipose tissue in people living with HIV, however, the effects on skeletal muscle fat and area are unknown. The goals of this exploratory secondary analysis were to determine the effects of tesamorelin on muscle quality (density) and quantity (area). Secondary, exploratory analysis of two previously completed randomized (2:1), clinical trials. U.S. and Canadian sites. People living with HIV and with abdominal obesity. Tesamorelin participants were restricted to responders (visceral adipose tissue decrease ≥8%). Tesamorelin or placebo. Computed tomography scans (at L4-L5) were used to quantify total and lean density (Hounsfield Units, HU) and area (centimeters2) of four trunk muscle groups using a semi-automatic segmentation image analysis program. Differences between muscle area and density before and after 26 weeks of tesamorelin or placebo treatment were compared and linear regression models were adjusted for baseline and treatment arm. Tesamorelin responders (n=193) and placebo (n=148) participants with available images were similar at baseline; most were Caucasian (83%) and male (87%). In models adjusted for baseline differences and treatment arm, tesamorelin was associated with significantly greater increases in density of four truncal muscle groups (coefficient 1.56-4.86 Hounsfield units; all p<0.005), and the lean anterolateral/abdominal and rectus muscles (1.39 and 1.78 Hounsfield units; both p<0.005) compared to placebo. Significant increases were also seen in total area of the rectus and psoas muscles (0.44 and 0.46 centimeters2; p<0.005), and in the lean muscle area of all four truncal muscle groups (0.64-1.08 centimeters2; p<0.005). Among those with clinically significant decrease in visceral adipose tissue on treatment, tesamorelin was effective in increasing skeletal muscle area and density. Long term effectiveness of tesamorelin among people with and without HIV, and the impact of these changes in daily life should be further studied.

Antiretroviral initiation is associated with increased skeletal muscle area and fat content.

A greater burden of physical function impairment occurs in HIV-infected adults; the impact of antiretroviral therapy (ART) initiation on muscle density (less dense = more fat), a measure of muscle quality, is unknown. AIDS Clinical Trials Group Study A5260s, a cardiometabolic substudy of A5257, randomized HIV-infected, ART-naive adults to ritonavir-boosted atazanavir, darunavir, or raltegravir with tenofovir/emtricitabine backbone. Single-slice abdominal computed tomography scans from baseline and week 96 were reanalyzed for total and lean muscle area and density. Two-sample t-tests described the differences between baseline and week 96 variables. Linear regression analysis was used to explore the role of a priori identified variables and potential confounders. Participants (n = 235) were mostly men (90%); 31% were Black non-Hispanic; 21% were Hispanic. Over 96 weeks, small but significant increases were seen in oblique/transverse abdominal, rectus, and psoas muscle total area (range 0.21-0.83 cm; P < 0.05) but not the lean muscle component (all P ≥ 0.33). Significant decreases in overall density, consistent with increases in fat, were seen in all muscle groups (range -0.87 to -2.4 HU; P < 0.01); for the lean muscle component, only decreases in oblique/transverse abdominal and rectus reached statistical significance (P < 0.05). In multivariable analyses, Black race was associated with increased muscle density and female sex with decreased density; treatment arm was not associated with changes in mass or density. The ART-associated increase in muscle area, regardless of regimen, is likely a reflection of increased fat within the muscle. The consequences of fatty infiltration of muscle on subsequent muscle function require further investigation.

Psoas Muscle Area and Length of Stay in Older Adults Undergoing Cardiac Operations

Frailty assessment can help predict which older adults will experience adverse events after cardiac surgical procedures. Low muscle mass is a core component of frailty that is suboptimally captured by self-reported weight loss; refined measures using computed tomographic (CT) images have emerged and are predictive of outcomes in noncardiac surgical procedures. The objective of this study was to evaluate the association between CT muscle area and length of stay (LOS) after cardiac surgical procedures. Frail patients who had a perioperative abdominal or thoracic CT scan were identified. The CT scans were analyzed to measure cross-sectional lean muscle area at the L4 vertebra (psoas muscle area [PMA], lumbar muscle area [LMA]) and the T4 vertebra (thoracic muscle area [TMA]). The associations of PMA, LMA, and TMA with frailty markers and postoperative LOS were investigated. Eighty-two patients were included; the mean age was 69.2 ± 9.97 years. Low muscle area was correlated with lower handgrip strength and short physical performance battery (SPPB) scores indicative of physical frailty. Postoperative LOS was correlated with PMA (R=-0.47, p= 0.004), LMA (R= -0.41, p= 0.01), and TMA (R= -0.29, p= 0.03). After adjustment for the predicted risk of prolonged LOS, age, sex, and body surface area, PMA remained significantly associated with LOS (β= -2.35, 95% CI -4.48 to -0.22). The combination of low PMA and handgrip strength, indicative of sarcopenia, yielded the greatest incremental value in predicting LOS. Low PMA is a marker of physical frailty associated with increased LOS in older adults undergoing cardiac surgical procedures. Further research is necessary to validate PMA as a prognostic marker and therapeutic target in this vulnerable population.

Cervical Intervertebral Disc Heights and Paraspinal Muscle Morphology Changes Following Long-term Spaceflight and 30-Day Recovery

Exposure to microgravity during long-duration spaceflights lengthens the spine is associated with a 5-fold greater incidence of herniated nucleus pulposus (HNP), particularly in the cervical region, compared with age-matched ground controls. Concurrent muscle atrophy or deconditioning may also contribute to increased HNP risk. PURPOSE: To evaluate cervical IVD height change and associated paraspinal muscle change following a 6-month International Space Station (ISS) mission and a 30-day post-flight recovery period. METHODS: Cervical spine MRI images were conducted pre-flight, immediate post-flight and 30-to-45 days post-flight recovery of 3 astronauts. IVD heights were measured at the anterior, middle and posterior sections from the upper C2-C3 to lower C7-T1 disc levels. Functional cross-sectional area measurements of the axial cervical paraspinal muscles at the C5-C6 level were performed. The fractional portion of lean muscle area was measured from a standardized region of interest within the posterior cervical extensors. Student-T tests were used to determine significant changes at p<0.05. RESULTS: Cervical IVD heights increased 0.35±0.42mm during the 6-month exposure to microgravity and recovered an average of 0.08±0.37mm over 30 days. The posterior aspect of the IVD heights was significantly decreased during recovery (0.30±0.36mm) while the anterior and middle segments remained swollen (Table 1). An average 9.9±17.8% decrease in cervical lean muscle tissue was measured post flight with a 30-day recovery of 2.2±3.8%. CONCLUSIONS: In the 30 days following ISS missions, there was significant reduction of the posterior cervical IVD heights associated with decreased lean muscle mass of posterior extensors. Supported by NASA grants NNX10AM18G and NNX13AM89G.

Null association between abdominal muscle and calcified atherosclerosis in community-living persons without clinical cardiovascular disease: The multi-ethnic study of atherosclerosis

ObjectiveLean muscle loss has been hypothesized to explain J-shaped relationships of body mass index (BMI) with cardiovascular disease (CVD), yet associations of muscle mass with CVD are largely unknown. We hypothesized that low abdominal lean muscle area would be associated with greater calcified atherosclerosis, independent of other CVD risk factors. Materials/MethodsWe investigated 1020 participants from the Multi-Ethnic Study of Atherosclerosis who were free of clinical CVD. Computed tomography (CT) scans at the 4th and 5th lumbar disk space were used to estimate abdominal lean muscle area. Chest and abdominal CT scans were used to assess coronary artery calcification(CAC), thoracic aortic calcification (TAC), and abdominal aortic calcification (AAC). ResultsThe mean age was 64±10years, 48% were female, and mean BMI was 28±5kg/m2. In models adjusted for demographics, physical activity, caloric intake, and traditional CVD risk factors, there was no inverse association of abdominal muscle mass with CAC (prevalence ratio [PR] 1.02 [95% CI 0.95,1.10]), TAC (PR 1.13 [95%CI 0.92, 1.39]) or AAC (PR 0.99 [95%CI 0.94, 1.04]) prevalence. Similarly, there was no significant inverse relationship between abdominal lean muscle area and CAC, TAC, and AAC severity. ConclusionIn community-living individuals without clinical CVD, greater abdominal lean muscle area is not associated with less calcified atherosclerosis.

Intramuscular adipose tissue and central activation in older adults

Intramuscular adipose tissue (IMAT) is a potential contributor to declining force production and may be related to impaired central activation; therefore, the purpose of this report is to describe IMAT composition and its association with central activation in older adults. The central activation ratio (CAR) of the knee extensors was assessed using a superimposition technique in 15 older adults (29 legs) along with the cross-sectional area of IMAT and lean tissue. IMAT and CAR are inversely related in older adults (r = -0.51, P = 0.005), and many subjects with high IMAT have deficits in central activation, whereas those with low IMAT have normal central activation. These novel findings may assist in unraveling why muscle force production and lean tissue cross-sectional area are not strongly linked, as the ability to centrally activate muscle appears to be unrelated to lean muscle area and may be dependent in part on IMAT levels.

Age-related changes in concentric and eccentric muscle strength in the lower and upper extremity: A cross-sectional study

Objective: To determine the influence of ageing on lean muscle area and isometric and concentric and eccentric muscle strength in the upper and lower extremity in a cross-sectional study design. Subjects and methods: Lean muscle area and maximal muscle strength (isometric and isokinetic, 60degrees and 120degrees/s) of both upper and lower extremity were assessed of 45 men and 56 women (20 to 89 years). Results: One-way variance analysis and regression analyses revealed a parallel decline with age in both sexes for maximal muscle strength. The decline in maximal muscle strength from age 60 was 34 to 45% in men and 11 to 32% in women in the arms and 40 to 47% in men and 37 to 45% in women in the legs. Isometric, concentric and eccentric contractions showed a similar decline in ageing in both sexes. There was a better maintenance with age of the strength in the arms than in the legs (p < 0.01) and at 120degrees/s than at 60degrees/s (p < 0.05). Conclusions: The present findings suggest a parallel decline in lean muscle area and strength and similar losses in isometric, concentric and eccentric strength with increasing age.