Imaging of sarcopenia: old evidence and new insights

Paradigm shift in gastrointestinal surgery − combating sarcopenia with prehabilitation: Multimodal review of clinical and scientific data

A growing body of evidence has demonstrated the prognostic significance of sarcopenia in surgical patients as an independent predictor of postoperative complications and outcomes. These included an increased risk of total complications, major complications, re-admissions, infections, severe infections, 30 d mortality, longer hospital stay and increased hospitalization expenditures. A program to enhance recovery after surgery was meant to address these complications; however, compliance to the program since its introduction has been less than ideal. Over the last decade, the concept of prehabilitation, or “pre-surgery rehabilitation”, has been discussed. The presurgical period represents a window of opportunity to boost and optimize the health of an individual, providing a compensatory “buffer” for the imminent reduction in physiological reserve post-surgery. Initial results have been promising. We review the literature to critically review the utility of prehabilitation, not just in the clinical realm, but also in the scientific realm, with a resource management point-of-view.

Above and Beyond Age: Prediction of Major Postoperative Adverse Events in Head and Neck Surgery

OBJECTIVE

Major postoperative adverse events (MPAEs) following head and neck surgery are not infrequent and lead to significant morbidity. The objective of this study was to ascertain which factors are most predictive of MPAEs in patients undergoing head and neck surgery.

METHODS

A cohort study was carried out based on data from patients registered in the National Surgical Quality Improvement Program (NSQIP) from 2006 to 2018. All patients undergoing non-ambulatory head and neck surgery based on Current Procedural Terminology codes were included. Perioperative factors were evaluated to predict MPAEs within 30-days of surgery. Age was classified as both a continuous and categorical variable. Retained factors were classified by attributable fraction and C-statistic. Multivariate regression and supervised machine learning models were used to quantify the contribution of age as a predictor of MPAEs.

RESULTS

A total of 43 701 operations were analyzed with 5106 (11.7%) MPAEs. The results of supervised machine learning indicated that prolonged surgeries, anemia, free tissue transfer, weight loss, wound classification, hypoalbuminemia, wound infection, tracheotomy (concurrent with index head and neck surgery), American Society of Anesthesia (ASA) class, and sex as most predictive of MPAEs. On multivariate regression, ASA class (21.3%), hypertension on medication (15.8%), prolonged operative time (15.3%), sex (13.1%), preoperative anemia (12.8%), and free tissue transfer (9%) had the largest attributable fractions associated with MPAEs. Age was independently associated with MPAEs with an attributable fraction ranging from 0.6% to 4.3% with poor predictive ability (C-statistic 0.60).

CONCLUSION

Surgical, comorbid, and frailty-related factors were most predictive of short-term MPAEs following head and neck surgery. Age alone contributed a small attributable fraction and poor prediction of MPAEs.

LEVEL OF EVIDENCE

3.

Machine Learning Models for Sarcopenia Identification Based on Radiomic Features of Muscles in Computed Tomography

The diagnosis of sarcopenia requires accurate muscle quantification. As an alternative to manual muscle mass measurement through computed tomography (CT), artificial intelligence can be leveraged for the automation of these measurements. Although generally difficult to identify with the naked eye, the radiomic features in CT images are informative. In this study, the radiomic features were extracted from L3 CT images of the entire muscle area and partial areas of the erector spinae collected from non-small cell lung carcinoma (NSCLC) patients. The first-order statistics and gray-level co-occurrence, gray-level size zone, gray-level run length, neighboring gray-tone difference, and gray-level dependence matrices were the radiomic features analyzed. The identification performances of the following machine learning models were evaluated: logistic regression, support vector machine (SVM), random forest, and extreme gradient boosting (XGB). Sex, coarseness, skewness, and cluster prominence were selected as the relevant features effectively identifying sarcopenia. The XGB model demonstrated the best performance for the entire muscle, whereas the SVM was the worst-performing model. Overall, the models demonstrated improved performance for the entire muscle compared to the erector spinae. Although further validation is required, the radiomic features presented here could become reliable indicators for quantifying the phenomena observed in the muscles of NSCLC patients, thus facilitating the diagnosis of sarcopenia.

Computed tomography-defined low skeletal muscle mass as a prognostic marker for short-term mortality in critically ill patients: A systematic review and meta-analysis

OBJECTIVE

Low skeletal muscle mass (LSMM) can be assessed by imaging modalities and is associated with several clinically relevant factors in critically ill patients. Our aim was to establish the effect of computed tomography (CT)-defined LSMM on short-term mortality in critically ill patients based on a large patient sample.

METHODS

The MedLine library and the Cochrane and SCOPUS databases were screened for associations between CT-defined LSMM and short-term mortality in critically ill patients up to May 2021. The primary endpoint of the systematic review was the odds ratio of sarcopenia on mortality. In total, nine studies were selected as suitable for the analysis and included into the present analysis.

RESULTS

The studies included a total of 1563 critically ill patients with different underlying diagnoses. The pooled overall prevalence of LSMM was 50.9%. The pooled odds ratio for the effect of sarcopenia on short-term mortality was 2.78 (95% confidence interval, 2.05-3.75).

CONCLUSIONS

CT-defined LSMM is highly prevalent in critically ill patients, has a relevant effect on short-term mortality, and should be included as a relevant prognostic biomarker in clinical routines.

Low CT attenuation and high fatty infiltration rate of psoas are risk factors for incisional hernias after appendicectomy: a cross-sectional single-center study from China

BACKGROUND

Decreased computed tomography (CT) attenuation of muscle is independently associated with muscle weakness. The CT attenuation of the abdominal wall muscles may correlate with that of the psoas in patients without ventral hernias. This means that the CT attenuation of the psoas may be related to the occurrence of incisional hernias (IH). CT-determined sarcopenia was deemed inefficient in predicting the development of IH, while limited attention has been paid to the association between muscle fatty infiltration and incidences of IH. In this study, we aim to investigate whether the psoas' CT measurement parameters, including the average CT attenuation, fatty infiltration rate and psoas muscle index, are associated with IH.

METHODS

In this study, adult patients who had undergone an appendicectomy in the past and had then, for any reason, been hospitalised in our hospital from January 2018 to December 2019 were enrolled. The patients were classified into an IH group and a non-IH group. Their psoas' CT attenuation, fatty infiltration rate (FIR) and psoas muscle index (PMI) were measured or calculated. Sarcopenia was defined according to their PMI. Differences between the two groups' indices were then compared. A logistic regression model was applied to assess the effects of psoas' CT measurement parameters on the occurrence of IH.

RESULTS

One hundred twenty patients were included in this study. The psoas' CT attenuation (p = 0.031) and PMI (p = 0.042) in the IH group were significantly lower than those in the non-IH group, and FIR in the IH group was significantly higher than in the non-IH group (p < 0.001). The patients' psoas' CT attenuation, FIR, PMI, age, gender and whether they had a history of smoking, were all significant factors in the univariate logistic regression analysis. After adjusting for confounding factors, a multivariate logistic regression analysis demonstrated that the psoas' CT attenuation was an independent protective factor (p = 0.042), and FIR was an independent risk factor (p = 0.018), while neither PMI (p = 0.118) nor sarcopenia (p = 0.663) showed a significant effect on the incidence of IH.

CONCLUSIONS

When an appendectomy has been performed, a decreased CT attenuation and increased FIR of the psoas can be considered risk factors for IH.

Effects of 16 Weeks of Resistance Training on Muscle Quality and Muscle Growth Factors in Older Adult Women with Sarcopenia: A Randomized Controlled Trial

This study examined the effects of resistance training on muscle quality, muscle growth factors, and functional fitness in older adult women with sarcopenia. Twenty-two older adult women aged over 65 with sarcopenia were randomly assigned to either resistance training (RT, n = 12) or non-exercise control group (CG, n = 10). The body weight-based and elastic band RT were performed three times a week, 60 min per session, for 16 weeks. Body composition and thigh muscle quality were estimated by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT), respectively. The muscle growth factors, including growth differentiation factor-8 (GDF-8), growth differentiation factor-15 (GDF-15), activin A, and follistatin, were analyzed via blood samples. Statistical analyses were performed using repeated measures multivariate analysis of variance (MANOVA), analysis of variance (ANOVA), and effect size (i.e., cohen’s d, partial eta square), and the significance level was set at 0.05. The RT group improved their functional fitness, grip strength, gait speed, and isometric muscle strength (p < 0.01, d > 0.99; large), while these variables did not change in the CG. An increase in intramuscular fat was only observed in the CG (p < 0.01, 1.06; large). Muscle growth factors such as follistatin were significantly increased in the RT (p < 0.05, 0.81; large), but other variables did not change following resistance training. Sixteen weeks of resistance training improved functional fitness and prevented age-related increases in intramuscular fat in the thigh area. However, there were only some changes in muscle growth factors, such as follistatin, suggesting that the effectiveness of resistance training on muscle growth factors is limited. Body weight-based and elastic band resistance training is an alternative training method for sarcopenia to minimize the age-related adverse effects on muscle function and quality.

Current Applications and Selected Technical Details of Dual-Energy X-Ray Absorptiometry

The application of dual-energy X-ray absorptiometry (DXA) examinations in the assessment of bone mineral density (BMD) in the lumbar spine, hip, and forearm is the basic diagnostic method for recognition of osteoporosis. The constant development of DXA technique is due to the aging of societies and the increasing importance of osteoporosis as a public health problem. In order to assess the degree of bone demineralization in patients with hyperparathyroidism, forearm DXA examination is recommended. The vertebral fracture assessment (VFA) of the thoracic and lumbar spine, performed by a highly-skilled technician, is an interesting alternative to the X-ray examination. The DXA total body examination can be useful in the evaluation of fat redistribution among patients after bariatric surgery, in patients infected with HIV and receiving antiretroviral therapy, and in patients with metabolic diseases and suspected to have sarcopenia. The assessment of visceral adipose tissue (VAT) and detection of abdominal aortic calcifications may be useful in the prediction of cardiovascular events. The positive effect of anti-resorptive therapy may affect some parameters of DXA hip structure analysis (HSA). Long-term anti-resorptive therapy, especially with the use of bisphosphonates, may result in changes in the DXA image, which may herald atypical femur fractures (AFF). Reduction of the periprosthetic BMD in the DXA measurements can be used to estimate the likelihood of loosening the prosthesis and periprosthetic fractures. The present review aims to present current applications and selected technical details of DXA.

A dynamic association between myosteatosis and liver stiffness: Results from a prospective interventional study in obese patients

Background & Aims

Retrospective cross-sectional studies linked sarcopenia and myosteatosis with metabolic dysfunction-associated fatty liver disease (MAFLD). Here, we wanted to clarify the dynamic relationship between sarcopenia, myosteatosis, and MAFLD.

Methods

A cohort of 48 obese patients was randomised for a dietary intervention consisting of 16 g/day of inulin (prebiotic) or maltodextrin (placebo) supplementation. Before and after the intervention, we evaluated liver steatosis and stiffness with transient elastography (TE); we assessed skeletal muscle index (SMI) and skeletal muscle fat index (SMFI) (a surrogate for absolute fat content in muscle) using computed tomography (CT) and bioelectrical impedance analysis (BIA).

Results

At baseline, sarcopenia was uncommon in patients with MAFLD (4/48, 8.3%). SMFI was higher in patients with high liver stiffness than in those with low liver stiffness (640.6 ± 114.3 cm²/ Hounsfield unit [HU] vs. 507.9 ± 103.0 cm²/HU, p = 0.001). In multivariate analysis, SMFI was robustly associated with liver stiffness even when adjusted for multiple confounders (binary logistic regression, p <0.05). After intervention, patients with inulin supplementation lost weight, but this was not associated with a decrease in liver stiffness. Remarkably, upon intervention (being inulin or maltodextrin), patients who lowered their SMFI, but not those who increased SMI, had a 12.7% decrease in liver stiffness (before = 6.36 ± 2.15 vs. after = 5.55 ± 1.97 kPa, p = 0.04).

Conclusions

Myosteatosis, but not sarcopenia, is strongly and independently associated with liver stiffness in obese patients with MAFLD. After intervention, patients in which the degree of myosteatosis decreased reduced their liver stiffness, irrespective of body weight loss or prebiotic treatment. The potential contribution of myosteatosis to liver disease progression should be investigated.

Clinical Trials registration number

NCT03852069.

Lay summary

The fat content in skeletal muscles (or myosteatosis) is strongly associated with liver stiffness in obese patients with MAFLD. After a dietary intervention, patients in which the degree of myosteatosis decreased also reduced their liver stiffness. The potential contribution of myosteatosis to liver disease progression should be investigated.

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Low-radiation CT scan enables muscle evaluation (quantity and composition).

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Muscle mass is not low in patients with MAFLD and high liver stiffness.

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In contrast, myosteatosis is strongly associated with liver stiffness.

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Lower myosteatosis after dietary intervention is associated with improved MAFLD.

Measurement of body composition: Agreement between methods of measurement by bioimpedance and computed tomography in patients with non-small cell lung cancer

BACKGROUND AND AIMS

Cancer cachexia is a muscle wasting syndrome which is promoted by the presence of inflammation and metabolic changes. Cancer cachexia has shown predictable for survival, progression of physical impairment as well as patient-reported outcomes. Being able to identify these patients with a clinically applicable method for measuring body composition could lead to early nutritional intervention, possibly preventing progression of cancer cachexia. This study aimed to investigate the agreement between body composition recorded with bioelectrical impedance analysis (BIA) and software analysis of CT scans of patients suffering from cancer with a special emphasis on muscle mass.

METHODS

This is a cross-sectional study of newly diagnosed patients with non-small cell lung cancer. All patients had muscle mass (MM) and fat mass (FM) measured by BIA with Tanita Segmental Body Composition Analyzer (BC-418) and by software analysis of CT scans at L3-level with VikingSlice. Secondary parameters (systemic inflammation, physical performance and electrolyte balance) were investigated for possible pitfalls of BIA. Patients who fulfilled best standard practice for BIA measurements, including 4 h of fasting, absence of oedema and no metallic implants, participated in a subgroup analysis. Agreement between method of measurements is investigated with the Bland and Altman method and pitfalls with paired t-test. A satisfactory agreement of BIA and CT measurements is established as ±10%.

RESULTS

A total of 60 patients participated in the study amongst which 37 participated in the subgroup analysis. The bias between methods of measurement for MM was 4.74 ± 11.55% (P = 0.002) with limits of agreement (LoA) of -17.91 to 27.38%. In the subgroup analysis, the bias of MM was 3.06 ± 10.71% (P = 0.091) and LoA were -17.94 to 24.06%. In the analysis of secondary parameters, significant differences between methods were found in patients with normal hand grip strength (1.83 kg, P = 0.023) and those performing under gender and age-specific cut-offs in the 30-s sit to stand test (5.15 kg, P = 0.009).

CONCLUSIONS

BIA and CT image analysis were not comparable for body composition measurements. BIA overestimated MM and underestimated FM with LoA outside that of the clinically assessed acceptable difference. Bias was reduced and LoA narrowed in the subgroup analysis however not to acceptable levels. This study finds it possible that patients with low physical performance are liable to larger overestimations of MM with BIA than those with normal physical performance.

Circulating Carboxylated Osteocalcin Correlates With Skeletal Muscle Mass and Risk of Fall in Postmenopausal Osteoporotic Women

Background

Bone and skeletal muscle represent a single functional unit. We cross-sectionally investigated body composition, risk of fall and circulating osteocalcin (OC) isoforms in osteoporotic postmenopausal women to test the hypothesis of an involvement of OC in the bone-muscle crosstalk.

Materials and Methods

Twenty-nine non-diabetic, non-obese, postmenopausal osteoporotic women (age 72.4 ± 6.8 years; BMI 23.0 ± 3.3 kg/m2) underwent to: 1) fasting blood sampling for biochemical and hormone assays, including carboxylated (cOC) and uncarboxylated (uOC) osteocalcin; 2) whole-body dual energy X-ray absorptiometry (DXA) to assess total and regional body composition; 3) magnetic resonance imaging to determine cross-sectional muscle area (CSA) and intermuscular adipose tissue (IMAT) of thigh muscles; 4) risk of fall assessment through the OAK system.

Results

Appendicular skeletal muscle index (ASMMI) was low in 45% of patients. Forty percent got a low OAK score, consistent with moderate-severe risk of fall, which was predicted by low legs lean mass and increased total fat mass. Circulating cOC levels showed significantly correlated with βCTx-I, lean mass parameters including IMAT, and OAK score. Fractured and unfractured women did not differ for any of the analyzed parameters, though cOC and uOC positively correlated with legs lean mass, OAK score and bone markers only in fractured women.

Conclusions

Data supported the relationship between OC and skeletal muscle mass and function in postmenopausal osteoporotic women. Serum cOC, but not uOC, emerges as mediator in the bone-muscle crosstalk. Circulating cOC and uOC levels may be differentially regulated in fractured and unfractured osteoporotic women, suggesting underlying differences in bone metabolism.

Detraining Effects on Muscle Quality in Older Men with Osteosarcopenia. Follow-Up of the Randomized Controlled Franconian Osteopenia and Sarcopenia Trial (FrOST)

The present study aimed to determine the effect of detraining on muscle quality (MQ) in older men with osteosarcopenia. Forty-three community-dwelling older men (78 ± 4 years) were randomly allocated to a consistently supervised high-intensity resistance exercise training (HIRT) group (n = 21) or a control group (CG, n = 22). The HIRT scheduled a periodized single set protocol twice weekly. After the intervention, the men were subjected to six months of detraining. Muscle quality (MQ), defined as maximum isokinetic hip/leg extensor strength per unit of mid-thigh intra-fascia volume, was determined by magnetic resonance imaging (MRI) or per unit of thigh muscle mass assessed by dual-energy X-ray absorptiometry (DXA). Intention-to-treat analysis with multiple imputations was applied. We observed significant exercise effects for MQ (p = 0.001). During detraining, the HIRT group lost about one-third of the intervention-induced gain and displayed significantly (p = 0.001) higher MQ reductions compared to the CG. Nevertheless, after training and detraining, the overall intervention effect on MQ remained significant (p ≤ 0.004). In summary, six months of absence from HIRT induce a significant deleterious effect on MQ in older osteosarcopenic men. We conclude that intermitted training programs with training breaks of six months and longer should be replaced by largely continuous exercise programs, at least when addressing MQ parameters.

Sarcopenia and Frailty in Liver Cirrhosis

Skeletal muscle is the largest organ in the body, and skeletal muscle atrophy results from a shift in the balance of protein synthesis and degradation toward protein breakdown. Primary sarcopenia is defined as a loss of skeletal muscle mass and strength or physical function due to aging, and secondary sarcopenia is defined as a loss of skeletal muscle mass and strength or physical function due to underlying diseases. Liver cirrhosis (LC) is one of the representative diseases which can be complicated with secondary sarcopenia. Muscle mass loss becomes more pronounced with worsening liver reserve in LC patients. While frailty encompasses a state of increased vulnerability to environmental factors, there is also the reversibility of returning to a healthy state with appropriate intervention. Several assessment criteria for sarcopenia and frailty were proposed in recent years. In 2016, the Japan Society of Hepatology created assessment criteria for sarcopenia in liver disease. In Japan, health checkups for frailty in the elderly aged 75 years or more started in April 2020. Both sarcopenia and frailty can be adverse predictors for cirrhotic patients. In this review article, we will summarize the current knowledge of sarcopenia and frailty in LC patients.

Preoperative sarcopenia is associated with poor overall survival in pancreatic cancer patients following pancreaticoduodenectomy

OBJECTIVES

To analyze the effect of preoperative body composition on survival in patients with pancreatic cancer following pancreaticoduodenectomy (PD).

METHODS

Between October 2005 and August 2018, 116 patients (68 men, 48 women, mean age 66.2 ± 11.9 years) diagnosed with pancreatic adenocarcinoma following PD were retrospectively enrolled. The preoperative CT on vertebral level L3 was assessed for total abdominal muscle area (TAMA), visceral adipose tissue area (VAT), subcutaneous adipose tissue area (SAT), and mean skeletal muscle attenuation (SMD). The clinical data and pathological findings of tumors were collected. The impact of these factors on disease-free survival (DFS) and overall survival (OS) was evaluated by the Kaplan-Meier method and by univariable and multivariable Cox proportional hazards models.

RESULTS

The 3-year DFS and OS rates were 8% and 25%, respectively. Of 116 patients, 20 (17.2%), 3 (2.6%), and 46 (39.7%) patients were classified as having sarcopenia, sarcopenic obesity, and myosteatosis, respectively. The VAT-TAMA ratio (1.2 ± 0.7 vs 0.9 ± 0.5, p = 0.01) and the visceral to subcutaneous adipose tissue area ratio (1.3 ± 0.7 vs 0.9 ± 0.5, p = 0.04) were higher in sarcopenic patients than in the nonsarcopenic group. Preoperative sarcopenia and sarcopenic obesity were associated with shorter OS (p = 0.012 and p = 0.041, respectively), but not shorter DFS. Myosteatosis was neither associated with DFS nor OS. On multivariable analysis, sarcopenia was the only significant prognostic factor for OS (p = 0.039).

CONCLUSIONS

Preoperative sarcopenia assessed by CT is a poor prognostic factor for OS in pancreatic cancer patients after PD.

KEY POINTS

• Sarcopenia and sarcopenic obesity can be evaluated by abdominal CT on L3 level. • Patients with diabetes mellitus (DM) had lower sex-standardized subcutaneous adipose tissue area index and skeletal muscle density and higher visceral to subcutaneous adipose tissue area ratio than did those without DM. • Preoperative sarcopenia, sarcopenic obesity, and new-onset diabetes mellitus may predict poor overall survival in pancreatic cancer patients following pancreaticoduodenectomy.

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

Background Lower muscle mass is a known predictor of unfavorable outcomes, but its prognostic impact on patients with COVID-19 is unknown. Purpose To investigate the contribution of CT-derived muscle status in predicting clinical outcomes in patients with COVID-19. Materials and Methods Clinical or laboratory data and outcomes (intensive care unit [ICU] admission and death) were retrospectively retrieved for patients with reverse transcriptase polymerase chain reaction-confirmed SARS-CoV-2 infection, who underwent chest CT on admission in four hospitals in Northern Italy from February 21 to April 30, 2020. The extent and type of pulmonary involvement, mediastinal lymphadenopathy, and pleural effusion were assessed. Cross-sectional areas and attenuation by paravertebral muscles were measured on axial CT images at the T5 and T12 vertebral level. Multivariable linear and binary logistic regression, including calculation of odds ratios (ORs) with 95% CIs, were used to build four models to predict ICU admission and death, which were tested and compared by using receiver operating characteristic curve analysis. Results A total of 552 patients (364 men and 188 women; median age, 65 years [interquartile range, 54-75 years]) were included. In a CT-based model, lower-than-median T5 paravertebral muscle areas 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 = .03). When clinical variables were included in the model, lower-than-median T5 paravertebral muscle areas still showed the highest ORs for both 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 receiver operating characteristic analysis, the CT-based model and the model including clinical variables showed the same area under the receiver operating characteristic curve (AUC) for ICU admission prediction (AUC, 0.83; P = .38) and were not different in terms of predicting death (AUC, 0.86 vs AUC, 0.87, respectively; P = .28). Conclusion In hospitalized patients with COVID-19, lower muscle mass on CT images was independently associated with intensive care unit admission and in-hospital mortality. © RSNA, 2021 Online supplemental material is available for this article.

Quantitative assessment of volumetric muscle loss: Dual-energy X-ray absorptiometry and ultrasonography

The generalized skeletal muscle disorder that involves (in elderly subjects) the progressive loss of muscle mass and function has been defined sarcopenia, whereas the rapid-onset (traumatic or surgical) and focal (unilateral) loss of skeletal muscle with resultant functional impairment has been defined volumetric muscle loss. Different tools and approaches are commonly used in the clinical settings to quantify the loss of muscle or lean mass and to assess the consequent motor impairment. This review describes the technical principles and provides a summary of the main parameters that can be obtained to assess lean mass (and its distribution) or muscle size (and its structure) through the two imaging techniques most easily accessible and therefore frequently adopted in the clinical practice: dual-energy X-ray absorptiometry and muscle ultrasonography.

Artificial intelligence-aided CT segmentation for body composition analysis: a validation study

Background

Body composition is associated with survival outcome in oncological patients, but it is not routinely calculated. Manual segmentation of subcutaneous adipose tissue (SAT) and muscle is time-consuming and therefore limited to a single CT slice. Our goal was to develop an artificial-intelligence (AI)-based method for automated quantification of three-dimensional SAT and muscle volumes from CT images.

Methods

Ethical approvals from Gothenburg and Lund Universities were obtained. Convolutional neural networks were trained to segment SAT and muscle using manual segmentations on CT images from a training group of 50 patients. The method was applied to a separate test group of 74 cancer patients, who had two CT studies each with a median interval between the studies of 3 days. Manual segmentations in a single CT slice were used for comparison. The accuracy was measured as overlap between the automated and manual segmentations.

Results

The accuracy of the AI method was 0.96 for SAT and 0.94 for muscle. The average differences in volumes were significantly lower than the corresponding differences in areas in a single CT slice: 1.8% versus 5.0% (p < 0.001) for SAT and 1.9% versus 3.9% (p < 0.001) for muscle. The 95% confidence intervals for predicted volumes in an individual subject from the corresponding single CT slice areas were in the order of ± 20%.

Conclusions

The AI-based tool for quantification of SAT and muscle volumes showed high accuracy and reproducibility and provided a body composition analysis that is more relevant than manual analysis of a single CT slice.

Use of artificial intelligence in the imaging of sarcopenia: A narrative review of current status and perspectives

Sarcopenia is a muscle disease which previously was associated only with aging, but in recent days it has been gaining more attention for its predictive value in a vast range of conditions and its potential link with overall health. Up to this point, evaluating sarcopenia with imaging methods has been time-consuming and dependent on the skills of the physician. The solution for this problem may be found in artificial intelligence, which may assist radiologists in repetitive tasks such as muscle segmentation and body-composition analysis. The major aim of this review was to find and present the current status and future perspectives of artificial intelligence in the imaging of sarcopenia. We searched the PubMed database to find articles concerning the use of artificial intelligence in diagnostic imaging and especially in body-composition analysis in the context of sarcopenia. We found that artificial-intelligence systems could potentially help with evaluating sarcopenia and better predicting outcomes in a vast range of clinical situations, which could get us closer to the true era of precision medicine.

Sarcopenic Obesity in Liver Cirrhosis: Possible Mechanism and Clinical Impact

The picture of chronic liver diseases (CLDs) has changed considerably in recent years. One of them is the increase of non-alcoholic fatty liver disease. More and more CLD patients, even those with liver cirrhosis (LC), tend to be presenting with obesity these days. The annual rate of muscle loss increases with worsening liver reserve, and thus LC patients are more likely to complicate with sarcopenia. LC is also characterized by protein-energy malnutrition (PEM). Since the PEM in LC can be invariable, the patients probably present with sarcopenic obesity (Sa-O), which involves both sarcopenia and obesity. Currently, there is no mention of Sa-O in the guidelines; however, the rapidly increasing prevalence and poorer clinical consequences of Sa-O are recognized as an important public health problem, and the diagnostic value of Sa-O is expected to increase in the future. Sa-O involves a complex interplay of physiological mechanisms, including increased inflammatory cytokines, oxidative stress, insulin resistance, hormonal disorders, and decline of physical activity. The pathogenesis of Sa-O in LC is diverse, with a lot of perturbations in the muscle-liver-adipose tissue axis. Here, we overview the current knowledge of Sa-O, especially focusing on LC.

Myosteatosis rather than sarcopenia associates with non-alcoholic steatohepatitis in non-alcoholic fatty liver disease preclinical models

BACKGROUND

Non-alcoholic fatty liver (NAFL) disease (NAFLD) is the most common chronic liver disease in the world. While most subjects have 'inert' NAFL, a subset will progress to non-alcoholic steatohepatitis (NASH) and its life-threatening complications. A substantial body of literature supports that a low muscle mass, low strength, and/or muscle fatty infiltration (myosteatosis) are associated with NAFLD severity. Here, we evaluated the muscle compartment in NASH preclinical models to decipher the kinetics of muscle alterations in relation with liver disease progression.

METHODS

We developed and validated a micro-computed tomography-based methodology to prospectively study skeletal muscle mass and density in muscle and liver (i.e. reflecting fatty infiltration) in a high-throughput and non-invasive manner in three preclinical NAFLD/NASH rodent models: fat aussie (FOZ) mice fed a high-fat diet (FOZ HF), wild-type (WT) mice fed a high-fat high-fructose diet (WT HFF), and WT mice fed a high-fat diet (WT HF). We compared them with WT mice fed a normal diet (WT ND) used as controls.

RESULTS

-FOZ HF with fibrosing NASH had sarcopenia characterized by a reduced muscle strength when compared with WT HF and WT HFF with early NASH and WT ND controls (165.2 ± 5.2 g vs. 237.4 ± 11.7 g, 256 ± 5.7 g, and 242.9 ± 9.3 g, respectively, P 60; 0.001). Muscle mass or strength was not lower in FOZ HF, WT HF, and WT HFF with early NASH than in controls. Myosteatosis was present in FOZ HF with fibrosing NASH, but also in FOZ HF, WT HF, and WT HFF with early NASH (muscle density = 0.50 ± 0.02, 0.62 ± 0.02, 0.70 ± 0.05, and 0.75 ± 0.03, respectively, with P 60; 0.001 when compared with respective controls). Myosteatosis degree was strongly correlated with NAFLD activity score (r = -0.87, n = 67, P 60; 0.001). In multivariate analysis, the association between myosteatosis and NASH was independent from homeostatic model assessment of insulin resistance and visceral fat area (P 60; 0.05). Myosteatosis degree powerfully discriminated NASH from benign NAFL and normal liver (area under the receiver operating characteristic = 0.96, n = 67, P 60; 0.001).

CONCLUSIONS

Taken together, our data support that there is no sarcopenia in obese mice with early NASH. In contrast, the severity of myosteatosis reflects on hepatocellular damage and inflammation during early NASH development. This observation prompts us to exploit myosteatosis as a novel non-invasive marker of NASH.

Towards Personalized Management of Sarcopenia in COPD

The awareness of the presence and consequences of sarcopenia has significantly increased over the past decade. Sarcopenia is defined as gradual loss of muscle mass and strength and ultimately loss of physical performance associated with aging and chronic disease. The prevalence of sarcopenia is higher in chronic obstructive pulmonary disease (COPD) compared to age-matched controls. Current literature suggests that next to physical inactivity, COPD-specific alterations in physiological processes contribute to accelerated development of sarcopenia. Sarcopenia in COPD can be assessed according to current guidelines, but during physical performance testing, ventilatory limitation should be considered. Treatment of muscle impairment can halt or even reverse sarcopenia, despite respiratory impairment. Exercise training and protein supplementation are currently at the basis of sarcopenia treatment. Furthermore, effective current and new interventions targeting the pulmonary system (eg, smoking cessation, bronchodilators and lung volume reduction surgery) may also facilitate muscle maintenance. Better understanding of disease-specific pathophysiological mechanisms involved in the accelerated development of sarcopenia in COPD will provide new leads to refine nutritional, exercise and physical activity interventions and develop pharmacological co-interventions.

Total-Body PET Imaging of Musculoskeletal Disorders

Imaging of musculoskeletal disorders, including arthritis, infection, osteoporosis, sarcopenia, and malignancies, is often limited when using conventional modalities such as radiography, computed tomography (CT), and MR imaging. As a result of recent advances in Positron Emission Tomography (PET) instrumentation, total-body PET/CT offers a longer axial field-of-view, higher geometric sensitivity, and higher spatial resolution compared with standard PET systems. This article discusses the potential applications of total-body PET/CT imaging in the assessment of musculoskeletal disorders.

Home-Based Resistance Training for Older Subjects during the COVID-19 Outbreak in Italy: Preliminary Results of a Six-Months RCT

BACKGROUND

The aim of this study was to evaluate the effect of a six-month home-based resistance-training program on muscle health and physical performance in healthy older subjects during the unique condition of home confinement caused by the COVID-19 pandemic.

METHODS

This was a randomized-controlled study that enrolled older participants that were allocated to either an experimental group performing the six-months exercise prescription (EXE) or a control group (CON). At the beginning (PRE), and after 6 months (POST), participants were assessed for muscle strength, balance, gait assessment and body composition by dual energy X-ray absorptiometry and magnetic resonance imaging. Normality distribution of data was checked with the D'Agostino and Pearson test and changes between PRE and POST were assessed by paired Student's t-test while percentage and absolute changes between groups at POST were tested by unpaired t-test.

RESULTS

Nine participants were included for the final analysis: EXE, n = 5 (age: 66 ± 4; BMI: 27.5 ± 3.7) and CON, n = 4 (age: 71 ± 9; BMI: 24.2 ± 4.1). Significant PRE-to-POST changes were observed in the EXE group only in the chair-stand test (+19.8%, p = 0.048 and ES:1.0, moderate) and in total fat mass (+5.0%, p = 0.035 and ES:1.4, large) with no between-group differences. Moreover, EXE had significantly higher absolute thigh CSA values than CON at POST (14.138 ± 2977 vs. 9039 ± 1015, p = 0.0178, ES = 1.7). No other within- and between-group differences were detected.

CONCLUSIONS

The home-based resistance-training program during the lockdown period, caused by the COVID-19 outbreak, determined only within-group improvement in lower limb muscle strength but not in muscle mass and composition in older subjects. Home confinement may partially explain the increase in total body fat due to a reduced daily PA regime and altered diet pattern.

Measurement of body mass by bioelectrical impedance analysis and computed tomography in cancer patients with malnutrition - a cross-sectional observational study

Malnutrition and cachexia affects the majority of cancer patients and significantly worsens their quality of life and prognosis. However, the diagnostic criteria of malnutrition and cachexia remain a topic under constant debate. To overcome this hurdle, diagnostic tools to objectively detect and quantify the loss of muscle and fat mass are needed. Computed tomography (CT)-based measurement is currently considered the golden standard. Bioelectrical impedance analysis (BIA) is an economical, non-invasive tool but it is seen controversial in patients with cancer and malnutrition because of possible estimation errors.BIA and CT-based analysis of body mass compartments were performed 172 times in 118 cancer patients, within the nutrition program of our institution. Prevalence of malnutrition was determined according to the global leadership initiative on malnutrition criteria. Data obtained for muscle and fat mass from both BIA and CT were correlated using Pearson's ρ. All analyses were performed with an explorative significance level of 5%.45.7% of the cohort were classified as "malnourished." No significant differences were observed between the 2 groups regarding demographic data. Median body mass index, Karnofsky performance status, and nutritional risk score were lower in the malnourished group. Values for muscle and fat mass by BIA and CT were significantly lower in malnourished patients. Correlation of the measured parameters were highly significant between CT-based and BIA measurement. In the overall cohort, correlation of measured muscle mass values by CT and BIA was significant with Pearson's ρ = 0.794 (P < .01). Looking at patients without malnutrition only, Pearson's ρ was 0.754 (P < .01). The correlation of measured fat mass values was equally significant, with Pearson's ρ of 0.748 (P < .01) in the overall cohort and 0.771 (P < .01) in patients with malnutrition.To our knowledge, this is the first study comparing BIA to CT-based body mass analysis in a large cohort of cancer patients with malnutrition. The results suggest that BIA is a valid diagnostic tool for the assessment of muscle and fat mass, even in patients with malnutrition, and could be implemented for the early detection and short-term follow-up of malnutrition and cachexia.

Preoperative computed tomography-assessed skeletal muscle index is a novel prognostic factor in patients with hepatocellular carcinoma following hepatectomy: a meta-analysis

Background

Recently, several studies have examined the association between preoperative sarcopenia and prognosis evaluation in patients with hepatocellular carcinoma (HCC) undergoing hepatectomy. However, their conclusions remain ambiguous and controversial. Thus, we conducted a meta-analysis to assess the prognostic role of preoperative sarcopenia in patients with HCC undergoing hepatectomy.

Methods

We searched the existing literature reporting on the prognostic value of preoperative computed tomography (CT)-assessed sarcopenia for the survival of patients with HCC undergoing hepatectomy. The pooled hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of overall survival (OS) and disease-free survival (DFS) were used to assess the prognostic value of preoperative sarcopenia in HCC patients. The associations between preoperative sarcopenia and clinicopathological characteristics were also evaluated.

Results

A total of six studies with 1,420 patients (including 458 sarcopenia and 962 non-sarcopenia patients) were included in the meta-analysis. The results showed that preoperative sarcopenia was significantly associated with poor OS (HR =1.572, 95% CI: 1.342-1.840, P=0) and shorter DFS (HR =1.544, 95% CI: 1.178-2.024, P=0.002) in patients with HCC undergoing hepatectomy. Preoperative sarcopenia was also significantly related to larger diameter tumors (WMD =0.598, 95% CI: 0.216-0.980, P=0.002). The results of the sensitivity analysis were stable in this meta-analysis. Egger's tests revealed that there was no significant publication bias.

Conclusions

Sarcopenia appears to have significant adverse impacts on postoperative outcomes in patients with hepatocellular carcinoma following hepatectomy. However, further large-scale prospective studies are needed to confirm our findings.

Prognostic relevance of temporal muscle thickness as a marker of sarcopenia in patients with glioblastoma at diagnosis

OBJECTIVES

Temporal muscle thickness (TMT) is a surrogate marker of sarcopenia, correlated with survival expectancy in patients suffering from brain metastases and recurrent or treated glioblastoma. We evaluated the prognostic relevance of TMT measured on brain MRIs acquired at diagnosis in patients affected by glioblastoma.

METHODS

We retrospectively enrolled 51 patients in our Institution affected by methylated MGMT promoter, IDH1-2 wild-type glioblastoma, who underwent complete surgical resection and subsequent radiotherapy with concomitant and maintenance temozolomide, from January 1, 2015, to April 30, 2017. The last clinical/radiological follow-up date was set to September 3, 2019. TMT was measured bilaterally on reformatted post-contrast 3D MPRAGE images, acquired on our 3-T scanner no more than 2 days before surgery. The median, 25th, and 75th percentile TMT values were identified and population was subdivided accordingly; afterwards, statistical analyses were performed to verify the association among overall survival (OS) and TMT, sex, age, and ECOG performance status.

RESULTS

In our cohort, the median OS was 20 months (range 3-51). Patients with a TMT ≥ 8.4 mm (median value) did not show a statistically significant increase in OS (Cox regression model: HR 1.34, 95% CI 0.68-2.63, p = 0.403). Similarly, patients with a TMT ≥ 9.85 mm (fourth quartile) did not differ in OS compared to those with TMT ≤ 7 mm (first quartile). The statistical analyses confirmed a significant association among TMT and sex (p = 0.0186), but none for age (p = 0.642) and performance status (p = 0.3982).

CONCLUSIONS

In our homogeneous cohort of patients with glioblastoma at diagnosis, TMT was not associated with prognosis, age, or ECOG performance status.

KEY POINTS

• Temporal muscle thickness (TMT) is a surrogate marker of sarcopenia and has been correlated with survival expectancy in patients suffering from brain metastases and recurrent or treated glioblastoma. • We appraised the correlation among TMT and survival, sex, age at surgery, and performance status, measured on brain MRIs of patients affected by glioblastoma at diagnosis. • TMT did not show any significant correlation with prognosis, age at surgery, or performance status, and its usefulness might be restricted only to patients with brain metastases and recurrent or treated glioblastoma.

Skeletal-muscle index predicts survival after percutaneous transhepatic biliary drainage for obstructive jaundice due to perihilar cholangiocarcinoma

BACKGROUND

Sarcopenia is emerging as a prognostic factor in patients with malignant diseases. The prognostication of perihilar cholangiocarcinoma (PHC) with obstructive jaundice was complex, because these patients suffered compete mortality events beyond cancer itself. Our study was to investigate the association between low skeletal-muscle index and overall survival (OS) after percutaneous transhepatic biliary drainage (PTBD) for obstructive jaundice due to PHC.

METHODS

We performed a retrospective survival analysis of patients undergoing PTBD for PHC-related obstructive jaundice between January 2016 and March 2019. Using computed tomography, we measured skeletal-muscle mass at the third lumbar vertebra (L3) to obtain a skeletal-muscle index (SMI). Then, we compared OS between low- and high-SMI groups. Furthermore, factors that could potentially affect OS were assessed.

RESULTS

One hundred and four patients (56 males; mean age 66 ± 12 years) were analyzed. Median OS after PTBD was 150 days. OS was shorter in patients with low SMI than in those with high SMI (median OS, 120 vs. 270 days; P < 0.001). Multivariate analysis indicated that low SMI (hazard ratio [HR] 3.46; 95% confidence interval [CI] 1.14-5.60; P < 0.001), intrahepatic metastasis (HR 2.98; 95% CI 1.89-4.69; P < 0.001) and elevated carbohydrate antigen (CA) 19-9 level (HR 1.00; 95% CI 1.00-1.00; P = 0.04) were significantly associated with OS.

CONCLUSION

Low SMI was a predictor of dismal OS after PTBD for patients with PHC-related obstructive jaundice.

Correlation between muscle mass and quality around the hip and of psoas muscles at L3 level using unenhanced CT scans

OBJECTIVE

CT segmentation of psoas muscles at L3 level is used to measure sarcopenia status, but it is not feasible when L3 is not included in the examination. We tested the correlation of psoas muscle mass and quality estimation at L3 with that of hip muscles, which could be opportunistically used in patients undergoing hip surgery.

MATERIALS AND METHODS

Unenhanced abdominal CT performed in 50 patients (29 males, mean/median age 69/72 years) were reviewed. Regions of interest were drawn to assess cross-sectional area (CSA) and attenuation of psoas muscles at L3. These values were correlated with CSA and attenuation of iliopsoas, rectus femoris, sartorius, and tensor fascia latae at the level of the hip, separately on each side. After applying Bonferroni correction for multiple comparisons, statistical significance was set as P < .002.

RESULTS

Attenuation of each psoas at L3 and ipsilateral hip muscles was significantly correlated (P ≤ .001, r = .491-.754). A significant correlation was observed between CSA of right psoas and ipsilateral muscles (P ≤ .00, r = .432-.525). We observed a significant correlation between CSA of left psoas and ipsilateral rectus femoris, iliopsoas, tensor fascia latae at the apex of the femoral head, and sartorius at the level of the lesser trochanter (P ≤ .001, r = .431-.502). Average time to measure CSA and attenuation of psoas muscles at L3 was 41 s, that of hip muscles was 2 min 12 s.

CONCLUSION

Measurements of mass and quality of hip muscles are feasible and correlate to those of psoas muscles at L3, being potentially used in future works on the association of sarcopenia and outcomes after hip surgery.

Quantitative Musculoskeletal Ultrasound

Ultrasound (US) imaging plays a crucial role in the assessment of musculoskeletal (MSK) disorders. Several quantitative tools are offered by US systems and add information to conventional US imaging. This article reviews the quantitative US imaging tools currently available in MSK radiology, specifically focusing on the evaluation of elasticity with shear-wave elastography, perfusion with contrast-enhanced US and noncontrast superb microvascular imaging, and bone and muscle mass with quantitative US methods. Some of them are well established and already of clinical value, such as elasticity and contrast-enhanced perfusion assessment in muscles and tendons. MSK radiologists should be aware of the potential of quantitative US tools and take advantage of their use in everyday practice, both for clinical and research purposes.

New insights on how and where to measure muscle mass

PURPOSE OF REVIEW

This article will discuss different muscle mass assessment methods and emphasize their highlights.

RECENT FINDINGS

Several measurement techniques can be used to evaluate muscle mass, recognized as important prognostic markers for adverse functional and clinical outcomes. Choosing the best method depends on the knowledge regarding their theoretical and practical limitations and the purpose of the assessment. Image techniques are considered the gold standards, with good accuracy and precision, but not always available in clinical settings. A new biological technique, the D3-creatinine dilution, can provide not only direct information about muscle mass but also shows a strong association with physical function. With the advancement of the use of the computed tomography (CT) images to assess skeletal muscle mass, mainly in patients with cancer, the assessment of skeletal muscle radiodensity (SMD), as a marker of muscle quality, may provide additional information regarding the association between muscle composition, muscle function and prognosis. Additional muscle function assessment can improve the risk prediction in several clinical situations.

SUMMARY

The use of the best tool for the muscle mass assessment should be performed carefully among the various methodologies, according to their characteristics and clinical situation.

Body composition with dual energy X-ray absorptiometry: from basics to new tools

Dual-energy X-ray absorptiometry (DXA) in nowadays considered one of the most versatile imaging techniques for the evaluation of metabolic bone disorders such as osteoporosis, sarcopenia and obesity. The advantages of DXA over other imaging techniques are the very low radiation dose, its accuracy and simplicity of use. In addition, fat mass (FM) and lean mass (LM) values by DXA shows very good accuracy compared to that of computed tomography and magnetic resonance imaging. In this review we will explain the technical working principles of body composition with DXA, together with the possible limitations and pitfalls that should be avoided in daily routine to produce high-quality DXA examinations. We will also cover the current clinical practical application of whole body DXA values, with particular emphasis on the use of LM indices in the diagnostic workup of reduced muscle mass, sarcopenia and osteosarcopenic obesity according to the most recent guidelines. The possible use of adipose indices will be considered, such as the fat mass index (FMI) or the android/gynoid ratio, as well as lipodystrophy indices and the evaluation of visceral adipose tissue (VAT). Whenever available, we will provide possible cut-off diagnostic values for each of these LM and FM indices, according to current literature and guidelines.

Sarcopenia: A Contemporary Health Problem among Older Adult Populations

Sarcopenia, a geriatric disease characterized by a progressive loss of skeletal muscle mass and loss of muscle function, constitutes a rising, often undiagnosed health problem. Its prevalence in the elderly population is largely considered variable, as it ranges from 5% to 50% depending on gender, age, pathological conditions as well as diagnostic criteria. There is no one unified approach of treatment or assessment, which makes sarcopenia even harder to assess. There is a pressing need to provide better diagnosis, diagnostics, prevention, and individualized health care. Physical activity and nutrition are the main studied ways to prevent sarcopenia, and they also offer better outcomes. This review aims to report the prevalence of sarcopenia in older adults, its etiology, prevention, and treatment techniques.

Sarcopenia in juvenile localized scleroderma: new insights on deep involvement

OBJECTIVES

Juvenile localized scleroderma (JLS) is a rare chronic autoimmune disease which can also affect bones and muscles. Nevertheless, muscle loss was not previously investigated in patients with JLS. Thus, the aim of this study was to retrospectively evaluate deep involvement and assess and quantify sarcopenia in JLS patients using magnetic resonance imaging (MRI).

METHODS

Fourteen children with JLS (nine females, mean age ± SD, 7.1 ± 3.6 years) referring to our tertiary center from January 2012 to January 2018 who underwent at least one MRI examination including axial T1-weighted and short tau inversion recovery images were included. Two readers assessed in consensus superficial and deep involvement. Muscle edema, muscle fatty infiltration, and sarcopenia were independently scored (absent, moderate, or severe) and the Cohen's kappa coefficient computed. Skin perimeter, subcutaneous area, muscle area, and muscle volume were independently measured using the contralateral unaffected extremity as reference (paired Student's t test, p < 0.05). The intraclass correlation coefficient (ICC) was used to investigate the reliability of the measurements.

RESULTS

All patients showed superficial involvement with subcutaneous fat atrophy being the most common finding (13 patients). Bone marrow edema occurred in five patients. Muscle edema affected ten children (moderate in seven, severe in three; k = 0.89), muscle fatty replacement occurred in one case (severe; k = 1.00), and sarcopenia was detected in eight patients (severe in two; k = 0.78). All quantitative parameters were lower on the affected side than on the unaffected contralateral limb (p < 0.05, each) and all measurements showed a high reliability (ICC > 0.750, each).

CONCLUSION

Patients with JLS can be affected by sarcopenia and quantitative analyses allow a robust characterization of such finding.

KEY POINTS

• Deep involvement in juvenile localized scleroderma is frequently characterized by sarcopenia. • In juvenile localized scleroderma, muscle edema and sarcopenia are mostly moderate while fatty infiltration, even if rare, can be severe. • Sarcopenia can be reliably quantified in children with juvenile localized scleroderma using MRI.