Quantifying Sarcopenia Reference Values Using Lumbar and Thoracic Muscle Areas in a Healthy Population

Normative data for age-specific skeletal muscle area based on computed tomography in Korean population

BACKGROUND

Sarcopenia, a progressive loss of muscle mass and function, increases health risks in older adults, especially in rapidly ageing populations like Korea. Computed tomography (CT) imaging at the third lumbar vertebra (L3) level is a gold standard for assessing skeletal muscle area (SMA) and indices (SMIs), yet age- and sex-specific reference values are limited. This multicentre study aimed to establish these values for improved sarcopenia diagnosis.

METHODS

We conducted a retrospective study with 2637 healthy Korean adults (1366 men, 1271 women) aged 20 and older, using abdominal CT scans from routine health check-ups at four centres. SMA and SMIs were measured at L3, and T-scores were calculated by comparing participants' values with a healthy young reference group (ages 20-39). Sarcopenia was classified into Classes I and II using standardised cutoffs.

RESULTS

An age-related SMA decline was observed in both sexes, with a more significant reduction in men. Sarcopenia prevalence was higher in men based on the SMA index, while SMA/body mass index (BMI) was more sensitive in women. Class I sarcopenia ranged from 10.1% to 21.3% in men and 10.6% to 23.6% in women, with Class II prevalence between 1.0% and 5.5% in men and 1.3% and 8.3% in women.

CONCLUSION

This study establishes CT-based reference values for SMA and SMIs, supporting early sarcopenia detection, with the SMA/BMI index proving valuable for both men and women.

Predictive factors for spontaneous dislodgement of percutaneous nephrostomies for malignant ureteral obstruction

PURPOSE

To investigate the etiology of spontaneous percutaneous nephrostomy (PCN) catheter dislodgements and evaluate factors potentially associated with these dislodgements, including muscle-to-fat composition and tissue characteristics of catheter traces.

MATERIALS AND METHODS

Data from 92 patients (63 males, 29 females; mean age 63.9 ± 11.4 years, range 28-88) undergoing 151 PCN catheter replacements between January 2016 and June 2021 were analyzed. Patients were divided into Group 1 (prophylactic replacements every 3 months, n = 41) and Group 2 (at least one spontaneous dislodgement, n = 51). Associations were evaluated for factors including intraabdominal visceral adipose tissue index (IAVATI), subcutaneous adipose tissue index (SATI), and abdominal perimeter. Other variables assessed were Eastern Cooperative Oncology Group (ECOG) performance status scores, psoas muscle index (PMI), renal size, renal parenchymal thickness, renal cortex-to-skin distance, posterolateral abdominal wall muscle thickness, and PCN replacement frequency.

RESULTS

No significant differences were identified between Group 1 and Group 2 in IAVATI, SATI, or abdominal perimeter values (p = 0.210-0.412). A significant difference in ECOG performance status scores (p = 0.0001), PMI (p = 0.04) and lower renal size, renal parenchymal thickness, renal cortex-to-skin distance, and posterolateral abdominal muscle thickness (p = 0.0001-0.039) were observed in Group 2. PCN replacements were significantly more frequent in Group 2 (p = 0.0001). Multivariate regression identified renal parenchymal thickness and abdominal wall muscle thickness as significant independent predictors (p = 0.0001, p = 0.02). ROC analysis yielded an AUC of 0.843 (95% CI: 0.769-0.917) for renal parenchymal thickness and 0.694 (95% CI: 0.610-0.778) for abdominal wall muscle thickness. Sensitivity and specificity rates were 73.1% and 96.4% for a 16 mm cutoff in renal parenchymal thickness, and 50.7% and 79.8% for an 8 mm cutoff in abdominal wall muscle thickness.

CONCLUSION

A significant association was identified between spontaneous PCN catheter dislodgement and both the psoas muscle index and ECOG performance status scores, while no notable relationship was observed with abdominal visceral or subcutaneous fat tissue volumes or abdominal perimeter. The risk of dislodgement was found to increase with reduced renal parenchymal and abdominal wall muscle thickness, as well as with more frequent nephrostomy replacements, suggesting these parameters may serve as useful markers for identifying patients at higher risk.

The risk factors for low back pain following oblique lateral interbody fusion: focus on sarcopenia

BACKGROUND

Sarcopenia had been identified as a factor influencing the postoperative outcomes of lumbar surgery. The effect of sarcopenia on the surgical outcomes in patients who underwent oblique lateral interbody fusion (OLIF) had not yet been examined.

OBJECTIVE

The aim of our study was to investigate the association between sarcopenia and postoperative low back pain (LBP) in patients following OLIF and provide recommendations for surgical strategy.

METHODS

116 patients who underwent OLIF were retrospectively reviewed. Patients were classified into sarcopenia group (Group SP) and non-sarcopenia group (Group NSP). According to whether instruments was performed, Group SP was further divided into OLIF stand-alone group (Group SP-SA) and OLIF with instruments group (Group SP-IN). The patient characteristics, surgical data and questionnaire scores were collected. Oswestry Disability Index (ODI) score was used to evaluate lumbar function and pain intensity. Multivariable logistic regression analysis was used to identify the risk factors for postoperative LBP.

RESULTS

There were 38 patients in Group SP and 78 patients in Group NSP. The incident rare of osteoporosis in Group SP was higher than that in Group NSP (P = 0.012). In Group SP, last follow-up intervertebral height (IH) was lower (P = 0.045) and incident rate of cage subsidence was higher ((P = 0.044). No significant difference (P = 0.229) showed in preoperative ODI scores, however, last follow-up ODI scores in Group SP was significantly higher (P = 0.017) than that in Group NSP. Multivariable logistic regression analysis showed that sarcopenia (P = 0.004), osteoporosis (P = 0.012) and cage subsidence (P = 0.002) were identified as risk factors for postoperative LBP. In Group SP-IN, last follow-up ODI score (P = 0.024) and incident rate of cage subsidence (P = 0.027) were significantly lower Compared to Group SP-SA.

CONCLUSIONS

LBP was a common complication following OLIF with the incidence rate of 18.1%. Sarcopenia, osteoporosis and cage subsidence were risk factors for LBP following OLIF. Instruments effectively reduced the incidence and degree of postoperative LBP in patients with sarcopenia following OLIF. Consequently, we suggest incorporating supplementary instruments for patients with sarcopenia in surgical strategy.

Evaluation of sarcopenia's relationship with overall survival and treatment toxicity in soft tissue sarcomas

AIM

The aim of our study is to evaluate the relationship between sarcopenia, overall survival (OS), and chemotherapy toxicity in patients with unresectable/metastatic soft tissue sarcoma (STS) treated with adriamycin and ifosfamide.

METHODS

Patients with unresectable/metastatic STS over the age of 18, diagnosed between 2015 and 2023, were included in the study. The study was conducted retrospectively in a single center. Total muscle volume at the lumbar 3 (L3) vertebra level was measured from the patient's computer tomography (CT) images. The skeletal muscle index (SMI) was calculated for each patient. Additionally, the prognostic nutritional index (PNI) was calculated for each patient using blood values.

RESULTS

Fifty-eight patients were included in the study. The median age of the patients was 51 years, Thirty-six (62.1%) were female and 22 (37.9%) were male. The SMI median was 49 cm2/m2 in male patients. ROC analysis demonstrated a statistically significant prediction of OS when the SMI index was < 49.2 cm2/m2. In female patients, the median SMI was 40 cm2/m2. ROC analysis demonstrated a statistically significant prediction of OS when the SMI index was < 40.3 cm2/m2. Median OS in the SMI < 49 cm2/m2 male group was 9 months (95% CI 7.99-10.08). In the SMI ≥ 49 cm2/m2 male group, the median OS was 30.2 months (95% CI 0.0-66.66). OS was statistically significant between the two groups (p = 0.003). The median OS in the SMI < 40 cm2/m2 female group was 20.5 months (95% CI 7.69-33.30). In the SMI ≥ 40 cm2/m2 female group, the median OS was 59.1 months (95% CI 21.36-96.98). OS was statistically significant between the two groups (p = 0.025). The relationship of SMI, as well as PNI, age, and Eastern Cooperative Oncology Group performance status (ECOG PS) with OS, was assessed. The relationship between SMI and chemotherapy toxicity was also evaluated. Chemotherapy-related toxicity was found to be significantly higher in sarcopenic patients (male SMI < 49 cm2/m2, female SMI < 40 cm2/m2) (p = 0.025).

CONCLUSIONS

A significant relationship was found between SMI and OS, but no significant relationship was found between PNI and OS. A significant relationship was also detected between SMI and treatment toxicity. Our study reveals that evaluating ECOG PS and sarcopenia in addition to grade and histological subtype when making treatment decisions will be associated with longer survival and less toxicity.

Sarcopenia diagnosed by computed tomography predicts postoperative complications in advanced epithelial ovarian cancer

BACKGROUND & AIMS

Surgery combined with chemotherapy remains the mainstay of treatment for advanced epithelial ovarian cancer. It is important to evaluate the occurrence of postoperative complications before operation and to prevent them. The purpose of this study is to investigate the role of sarcopenia diagnosed by CT scans in predicting postoperative complications in patients with ovarian cancer.

METHODS

Patients with PDS or IDS in the First Affiliated Hospital of Wenzhou Medical University from August 2017 to August 2022 were included. Sarcopenia was identified using CT scans at the T12 level. According to the Clavien-Dindo classification, postoperative complications are considered to have occurred in grades 2 and above. Logistic regression analysis was used to identify risk factors contributing to postoperative complications. P < 0.05 was considered statistically significant.

RESULTS

A total of 139 patients were included. Sarcopenia was observed in 24(17.27%) patients with advanced epithelial ovarian cancer. Compared to the non-sarcopenia group, the sarcopenia group had a higher incidence of postoperative complications (62.50% VS 42.61%, p = 0.032). Multivariate logistic analysis confirmed sarcopenia (OR = 3.241, p = 0.026), age over 65 years (OR = 3.296, p = 0.005), and intraoperative bleeding (OR = 1.002, p < 0.001) as independent predictors of postoperative complications in ovarian cancer.

DISCUSSION & CONCLUSIONS

Sarcopenia diagnosed based on CT body composition analysis may serve as a potential predictor for postoperative complications. Further research is warranted to explore preventive strategies and interventions to improve outcomes in this population.

Ethnic differences in CT derived abdominal body composition measures: a comparative retrospect pilot study between European and Inuit study population

Understanding ethnic variations in body composition is crucial for assessing health risks. Universal models may not suit all ethnicities, and there is limited data on the Inuit population. This study aimed to compare body composition between Inuit and European adults using computed tomography (CT) scans and to investigate the influence of demographics on these measurements. A retrospective analysis was conducted on 50 adults (29 Inuit and 21 European) who underwent standard trauma CT scans. Measurements focused on skeletal muscle index (SMI), various fat indices, and densities at the third lumbar vertebra level, analyzed using the Wilcoxon-Mann-Whitney test and multiple linear regression. Inuit women showed larger fat tissue indices and lower muscle and fat densities than European women. Differences in men were less pronouncehd, with only Intramuscular fat density being lower among Inuit men. Regression indicated that SMI was higher among men, and skeletal muscle density decreased with Inuit ethnicity and age, while visceral fat index was positively associated with age. This study suggests ethnic differences in body composition measures particularly among women, and indicates the need for Inuit-specific body composition models. It higlights the importance of further research into Inuit-specific body composition measurements for better health risk assessment.

The Emerging Role and Clinical Applications of Morphomics in Diagnostic Imaging

Analytic morphomics refers to the accurate measurement of specific biological markers of human body composition in diagnostic medical imaging. The increasing prevalence of disease processes that alter body composition including obesity, cachexia, and sarcopenia has generated interest in specific targeted measurement of these metrics to possibly prevent or reduce negative health outcomes. Typical morphomic measurements include the area and density of muscle, bone, vascular calcification, visceral fat, and subcutaneous fat on a specific validated axial level in the patient's cross-sectional diagnostic imaging. A distinct advantage of these measurements is that they can be made retrospectively and opportunistically with pre-existing datasets. We provide a narrative review of the current state of art in morphomics, but also consider some potential future directions for this exciting field. Imaging based quantitative assessment of body composition has enormous potential across the breadth and scope of modern clinical practice. From risk stratification to treatment planning, and outcome assessment, all can be enhanced with the use of analytic morphomics. Moreover, it is likely that many new opportunities for personalized medicine will emerge as the field evolves. As radiologists, embracing analytic morphomics will enable us to contribute added value in the care of every patient.

Association of computed tomography-derived pectoralis muscle area and density with disease severity and respiratory symptoms in patients with chronic obstructive pulmonary disease: A case-control study

RATIONALE AND OBJECTIVES

Computed tomography (CT) is commonly used and offers an additional viewpoint for evaluating extrapulmonary symptoms, disease severity, and muscle atrophy. This study assessed whether the pectoralis muscle area (PMA) and pectoralis muscle density (PMD) are lower in patients with chronic obstructive pulmonary disease (COPD) than in healthy controls and elucidated their relationships with these variables.

MATERIALS AND METHODS

The participants were enrolled in the hospital outpatient clinic between October 2023 and May 2024. Information was obtained from questionnaires, lung function, and CT imaging findings. On full-inspiratory CT, the PMA and PMD were measured at the aortic arch level using predetermined attenuation ranges of -29 and 150 Hounsfield units. We observed lower PMA and PMD and evaluated their associations with lung function, respiratory symptoms, and CT imaging findings in patients with COPD.

RESULTS

Overall, 120 participants were enrolled at baseline (60 healthy controls and 60 patients with COPD). PMA and PMD were lower with progressive airflow limitation severity in those with COPD. The degree of emphysema and air trapping, as well as lung function, were correlated with PMA and PMD (P < 0.05), although not with the COPD Assessment Test or modified Medical Research Council scores (P > 0.05).

CONCLUSION

Participants with COPD had smaller PMA and PMD. These measurements were correlated with the severity of airflow limitation, lung function, emphysema, and air trapping, suggesting that these features of the pectoralis muscle obtained from CT are helpful in assessments of patients with COPD.

Skeletal muscle size and quality in healthy kidney donors, normal range and clinical associations

The gold standard to estimate muscle mass and quality is computed tomography (CT) scan. Lower mass and density (intramuscular fat infiltration) of skeletal muscles are markers of sarcopenia, associated with increased mortality risk, impaired physical function, and poorer prognosis across various populations and medical conditions. We aimed to describe standard reference values in healthy population, prospective kidney donors, and correlate clinical parameters to muscle mass and density. Included in the cohort 384 consecutive kidney donors. Mean age was 44.6 ± 11.5 (range 18.4-74.2), 46% were female and mean BMI was 25.6 ± 3.8 kg/m2. Our quantified reference values for psoas cross -sectional area (CSA) index at L3 level (males/females respectively) were 6.3 ± 1.8 and 4.8 ± 1.9 cm2 /m2, and density was 46.1 ± 5 and 41 ± 5 HU at that level. Older age (standardized beta coefficient - 0.12, p = 0.04), sex (- 0.32, p < 0.001) and BMI (0.17, p = 0.002) were significantly associated with CSA index of psoas at L3. Density, however, was associated with triglycerides level (- 0.21, p < 0.001), in addition to age (- 0.22, p < 0.0001), sex (- 0.27, p < 0.001) and BMI (- 0.1, p = 0.05). Our study validates the normative values of psoas muscle mass and density in healthy individuals and suggests correlations with clinical parameters. We demonstrate the significance of measuring not only the mass of the muscle, but also its density, as it has a valid association with metabolic parameters, including BMI and lipid level, even in healthy individuals and in the normal range of the tests.

Incorporation of quantitative imaging data using artificial intelligence improves risk prediction in veterans with liver disease

BACKGROUND AND AIMS

Utilization of electronic health records data to derive predictive indexes such as the electronic Child-Turcotte-Pugh (eCTP) Score can have significant utility in health care delivery. Within the records, CT scans contain phenotypic data which have significant prognostic value. However, data extractions have not traditionally been applied to imaging data. In this study, we used artificial intelligence to automate biomarker extraction from CT scans and examined the value of these features in improving risk prediction in patients with liver disease.

APPROACH AND RESULTS

Using a regional liver disease cohort from the Veterans Health System, we retrieved administrative, laboratory, and clinical data for Veterans who had CT scans performed for any clinical indication between 2008 and 2014. Imaging biomarkers were automatically derived using the analytic morphomics platform. In all, 4614 patients were included. We found that the eCTP Score had a Concordance index of 0.64 for the prediction of overall mortality while the imaging-based model alone or with eCTP Score performed significantly better [Concordance index of 0.72 and 0.73 ( p <0.001)]. For the subset of patients without hepatic decompensation at baseline (n=4452), the Concordance index for predicting future decompensation was 0.67, 0.79, and 0.80 for eCTP Score, imaging alone, or combined, respectively.

CONCLUSIONS

This proof of concept demonstrates that the potential of utilizing automated extraction of imaging features within CT scans either alone or in conjunction with classic health data can improve risk prediction in patients with chronic liver disease.

Assessment of Psoas Muscle Index in Middle-Aged Type 2 Diabetes Patients: Impact of Insulin Therapy on Sarcopenia

OBJECTIVE

Sarcopenia, characterized by progressive skeletal muscle loss, poses significant health risks, including physical impairment and mortality. The relationship between sarcopenia and insulin resistance suggests insulin therapy's potential in preserving muscle mass, particularly in Type 2 diabetes mellitus (T2DM) patients. This study aims to evaluate the Psoas Muscle Index (PMI) via computed tomography (CT) in middle-aged T2DM patients on insulin therapy versus oral antidiabetic drugs (OAD) and controls.

METHODS

This retrospective study included 107 middle-aged T2DM patients undergoing non-contrast CT scans and 58 age-matched controls. CT images were analyzed to calculate PMI. Statistical analysis included Chi-square tests, independent samples t-tests, Mann-Whitney U tests, and correlation analyses.

RESULTS

Insulin-treated patients exhibited higher PMI than OAD users (p < 0.001), while OAD users had lower PMI than controls (p < 0.001). No significant difference was found between insulin-treated patients and controls (p = 0.616). Negative correlations were observed between T2DM duration/age and PMI across all groups, with a positive correlation between T2DM duration and BMI observed in the OAD group.

CONCLUSIONS

Insulin therapy in T2DM patients, regardless of age or disease duration, positively impacts muscle mass, highlighting its potential in preserving muscular health and advocating for tailored treatment strategies in T2DM management.

The role of sarcopenia in fragility fractures of the pelvis - is sarcopenia an underestimated risk factor?

BACKGROUND

Fragility fractures of the pelvis (FFPs) represent a significant health burden, particularly for the elderly. The role of sarcopenia, an age-related loss of muscle mass and function, in the development and impact of these fractures is not well understood. This study aims to investigate the prevalence and impact of osteoporosis and sarcopenia in patients presenting with FFPs.

METHODS

This retrospective study evaluated 140 elderly patients with FFPs. The diagnosis of sarcopenia was assessed by psoas muscle area (PMA) and the height-adjusted psoas muscle index (PMI) measured on computed tomography (CT) scans. Clinical data, radiological findings and functional outcomes were recorded and compared with the presence or absence of sarcopenia and osteoporosis.

RESULTS

Our study cohort comprised 119 female (85.0%) and 21 (15.0%) male patients. The mean age at the time of injury or onset of symptoms was 82.26 ± 8.50 years. Sarcopenia was diagnosed in 68.6% (n = 96) patients using PMA and 68.8% (n = 88) using PMI. 73.6% (n = 103) of our study population had osteoporosis and 20.0% (n = 28) presented with osteopenia. Patients with sarcopenia and osteoporosis had longer hospital stays (p < 0.04), a higher rate of complications (p < 0.048) and functional recovery was significantly impaired, as evidenced by a greater need for assistance in daily living (p < 0.03). However, they were less likely to undergo surgery (p < 0.03) and the type of FFP differed significantly (p < 0.04). There was no significant difference in mortality rate, pre-hospital health status, age or gender.

CONCLUSION

Our study highlights the important role of sarcopenia in FFPs in terms of the serious impact on health and quality of life in elderly patients especially when osteoporosis and sarcopenia occur together. Identifying and targeting sarcopenia in older patients may be an important strategy to reduce pelvic fractures and improve recovery. Further research is needed to develop effective prevention and treatment approaches that target muscle health in the elderly.

Association between Muscle Mass Index and Neurological Outcomes of Patients with Out-of-Hospital Cardiac Arrest

Muscle mass depletion is associated with unfavorable outcomes in many diseases. However, its relationship with cardiac arrest outcomes has not been explored. This retrospective single-center study determined the relationship between muscle mass depletion and the neurological outcomes of patients with out-of-hospital cardiac arrest (OHCA) by measuring muscle mass at various locations. Adult patients with OHCA, who were treated with target temperature management, and who underwent abdominal or chest computed tomography (CT) within 3 months of the cardiac arrest were included. Skeletal muscle index (SMI) was measured at the third lumbar vertebra (L3) level, psoas muscle, fourth thoracic vertebra (T4) level, and pectoralis muscle. The Youden index was used to determine a low SMI based on sex-specific cutoff values. The outcome variables were "good neurological outcome" and "survival" at hospital discharge. Multivariable analyses revealed that patients with low T4 SMI level were significantly associated with good neurological outcomes at hospital discharge (odds ratio = 0.26, 95% confidence interval: 0.07-0.88, p = 0.036). However, no significant differences were observed between good neurological outcomes and low SMI at the L3 level and psoas and pectoralis muscles; SMIs were not associated with survival at hospital discharge. T4 level SMI depletion was inversely associated with good neurological outcomes in patients with OHCA. Thoracic muscle depletion may be crucial for predicting the neurological outcomes in patients with OHCA and further investigation in larger prospective study is warranted.

Multimodal prerehabilitation for elderly patients with sarcopenia in colorectal surgery

Sarcopenia, which is characterized by progressive and generalized loss of skeletal muscle mass and strength, has been well described to be associated with numerous poor postoperative outcomes, such as increased perioperative mortality, postoperative sepsis, prolonged length of stay, increased cost of care, decreased functional outcome, and poorer oncological outcomes in cancer surgery. Multimodal prehabilitation, as a concept that involves boosting and optimizing the preoperative condition of a patient prior to the upcoming stressors of a surgical procedure, has the purported benefits of reversing the effects of sarcopenia, shortening hospitalization, improving the rate of return to bowel activity, reducing the costs of hospitalization, and improving quality of life. This review aims to present the current literature surrounding the concept of sarcopenia, its implications pertaining to colorectal cancer and surgery, a summary of studied multimodal prehabilitation interventions, and potential future advances in the management of sarcopenia.

Automatic deep learning method for third lumbar selection and body composition evaluation on CT scans of cancer patients

Introduction

The importance of body composition and sarcopenia is well-recognized in cancer patient outcomes and treatment tolerance, yet routine evaluations are rare due to their time-intensive nature. While CT scans provide accurate measurements, they depend on manual processes. We developed and validated a deep learning algorithm to automatically select and segment abdominal muscles [SM], visceral fat [VAT], and subcutaneous fat [SAT] on CT scans.

Materials and Methods

A total of 352 CT scans were collected from two cancer centers. The detection of the third lumbar vertebra and three different body tissues (SM, VAT, and SAT) were annotated manually. The 5-fold cross-validation method was used to develop the algorithm and validate its performance on the training cohort. The results were validated on an external, independent group of CT scans.

Results

The algorithm for automatic L3 slice selection had a mean absolute error of 4 mm for the internal validation dataset and 5.5 mm for the external validation dataset. The median DICE similarity coefficient for body composition was 0.94 for SM, 0.93 for VAT, and 0.86 for SAT in the internal validation dataset, whereas it was 0.93 for SM, 0.93 for VAT, and 0.85 for SAT in the external validation dataset. There were high correlation scores with sarcopenia metrics in both internal and external validation datasets.

Conclusions

Our deep learning algorithm facilitates routine research use and could be integrated into electronic patient records, enhancing care through better monitoring and the incorporation of targeted supportive measures like exercise and nutrition.

Opportunistic assessment of ischemic heart disease risk using abdominopelvic computed tomography and medical record data: a multimodal explainable artificial intelligence approach

Current risk scores using clinical risk factors for predicting ischemic heart disease (IHD) events-the leading cause of global mortality-have known limitations and may be improved by imaging biomarkers. While body composition (BC) imaging biomarkers derived from abdominopelvic computed tomography (CT) correlate with IHD risk, they are impractical to measure manually. Here, in a retrospective cohort of 8139 contrast-enhanced abdominopelvic CT examinations undergoing up to 5 years of follow-up, we developed multimodal opportunistic risk assessment models for IHD by automatically extracting BC features from abdominal CT images and integrating these with features from each patient's electronic medical record (EMR). Our predictive methods match and, in some cases, outperform clinical risk scores currently used in IHD risk assessment. We provide clinical interpretability of our model using a new method of determining tissue-level contributions from CT along with weightings of EMR features contributing to IHD risk. We conclude that such a multimodal approach, which automatically integrates BC biomarkers and EMR data, can enhance IHD risk assessment and aid primary prevention efforts for IHD. To further promote research, we release the Opportunistic L3 Ischemic heart disease (OL3I) dataset, the first public multimodal dataset for opportunistic CT prediction of IHD.

Reference distributions of aortic calcification and association with Framingham risk score

Evidence supporting aortic calcification as a leverageable cardiovascular risk factor is rapidly growing. Given aortic calcification's potential as a clinical correlate, we assessed granular vertebral-indexed calcification measurements of the abdominal aorta in a well curated reference population. We evaluated the relationship of aortic calcification measurements with Framingham risk scores. After exclusion, 4073 participants from the Reference Analytic Morphomic Population with varying vertebral levels were included. The percent of the aortic wall calcified was used to assess calcification burden at the L1-L4 levels. Descriptive statistics of participants, sex-specific vertebral indexed calcification measurements, relational plots, and relevant associations are reported. Mean aortic attenuation was higher in female than male participants. Overall, mean aortic calcium was higher with reference to inferior abdominal aortic measurements and demonstrated significant differences across all abdominal levels [L3 Area (mm[Formula: see text]): Females 6.34 (sd 16.60), Males 6.23 (sd 17.21); L3 Volume (mm[Formula: see text]): Females 178.90 (sd 474.19), Males 195.80 (sd 547.36); Wall Calcification (%): Females (L4) 6.97 (sd 16.03), Males (L3) 5.46 (13.80)]. Participants with elevated calcification had significantly higher Framingham risk scores compared to participants with normal calcification scores. Opportunistically measuring aortic calcification may inform further cardiovascular risk assessment and enhance cardiovascular event surveillance efforts.

Association between thoracic and third lumbar CT-derived muscle mass and density in Caucasian patients without chronic disease: a proof-of-concept study

BACKGROUND

Computed tomography (CT) is increasingly used in the clinical workup, and existing scan contains unused body composition data, potentially useful in a clinical setting. However, there is no healthy reference for contrast-enhanced thoracic CT-derived muscle measures. Therefore, we aimed at investigating whether there is a correlation between each of the thoracic and third lumbar vertebra level (L3) skeletal muscle area (SMA), skeletal muscle index (SMI), and skeletal muscle density (SMD) at contrast-enhanced CT in patients without chronic disease.

METHODS

A proof-of-concept retrospective observational study was based on Caucasian patients without chronic disease, who received CT for trauma between 2012 and 2014. Muscle measures were assessed using a semiautomated threshold-based software by two raters independently. Pearson's correlation between each thoracic level and third lumbar and intraclass correlation between two raters and test-retest with SMA as proxy parameters were used.

RESULTS

Twenty-one patients (11 males, 10 females; median age 29 years) were included. The second thoracic vertebra (T2) had the highest median of cumulated SMA (males 314.7 cm², females 118.5 cm²) and SMI (97.8 cm²/m² and 70.4 cm²/m², respectively). The strongest SMA correlation was observed between T5 and L3 (r = 0.970), the SMI between T11 and L3 (r = 0.938), and the SMD between the T10 and L3 (r = 0.890).

CONCLUSIONS

This study suggests that any of the thoracic levels can be valid to assess skeletal muscle mass. However, the T5 may be most favourable for measuring SMA, the T11 for SMI, and T10 for SMD when using contrast-enhanced thoracic CT.

RELEVANCE STATEMENT

In COPD patients, a CT-derived thoracic muscle mass assessment may help identify who would benefit from focused pulmonary rehabilitation: thoracic contrast-enhanced CT conducted as part of the standard clinical workup can be used for this evaluation.

KEY POINTS

• Any thoracic level can be used to assess thoracic muscle mass. • Thoracic level 5 is strongly associated with the 3rd lumbar muscle area. • A strong correlation between the thoracic level 11 and the 3rd lumbar muscle index. • Thoracic level 10 is strongly associated with the 3rd lumbar muscle density.

Sarcopenia provides extra value outside the PULP score for predicting mortality in older patients with perforated peptic ulcers

BACKGROUND

Perforated peptic ulcer (PPU) remains challenging surgically due to its high mortality, especially in older individuals. Computed tomography (CT)-measured skeletal muscle mass is a effective predictor of the surgical outcomes in older patients with abdominal emergencies. The purpose of this study is to assess whether a low CT-measured skeletal muscle mass can provide extra value in predicting PPU mortality.

METHODS

This retrospective study enrolled older (aged ≥ 65 years) patients who underwent PPU surgery. Cross-sectional skeletal muscle areas and densities were measured by CT at L3 and patient-height adjusted to obtain the L3 skeletal muscle gauge (SMG). Thirty-day mortality was determined with univariate, multivariate and Kaplan-Meier analysis.

RESULTS

From 2011 to 2016, 141 older patients were included; 54.8% had sarcopenia. They were further categorized into the PULP score ≤ 7 (n=64) or PULP score > 7 group (n=82). In the former, there was no significant difference in 30-day mortality between sarcopenic (2.9%) and nonsarcopenic patients (0%; p=1.000). However, in the PULP score > 7 group, sarcopenic patients had a significantly higher 30-day mortality (25.5% vs. 3.2%, p=0.009) and serious complication rate (37.3% vs. 12.9%, p=0.017) than nonsarcopenic patients. Multivariate analysis showed that sarcopenia was an independent risk factor for 30-day mortality in patients in the PULP score > 7 group (OR: 11.05, CI: 1.03-118.7).

CONCLUSION

CT scans can diagnose PPU and provide physiological measurements. Sarcopenia, defined as a low CT-measured SMG, provides extra value in predicting mortality in older PPU patients.

Human skeletal muscle-specific atrophy with aging: a comprehensive review

Age-related skeletal muscle atrophy appears to be a muscle group-specific process, yet only a few specific muscles have been investigated and our understanding in this area is limited. This review provides a comprehensive summary of the available information on age-related skeletal muscle atrophy in a muscle-specific manner, nearly half of which comes from the quadriceps. Decline in muscle-specific size over ∼50 yr of aging was determined from 47 cross-sectional studies of 982 young (∼25 yr) and 1,003 old (∼75 yr) individuals and nine muscle groups: elbow extensors (-20%, -0.39%/yr), elbow flexors (-19%, -0.38%/yr), paraspinals (-24%, -0.47%/yr), psoas (-29%, -0.58%/yr), hip adductors (-13%, -0.27%/yr), hamstrings (-19%, -0.39%/yr), quadriceps (-27%, -0.53%/yr), dorsiflexors (-9%, -0.19%/yr), and triceps surae (-14%, -0.28%/yr). Muscle-specific atrophy rate was also determined for each of the subcomponent muscles in the hamstrings, quadriceps, and triceps surae. Of all the muscles included in this review, there was more than a fivefold difference between the least (-6%, -0.13%/yr, soleus) to the most (-33%, -0.66%/yr, rectus femoris) atrophying muscles. Muscle activity level, muscle fiber type, sex, and timeline of the aging process all appeared to have some influence on muscle-specific atrophy. Given the large range of muscle-specific atrophy and the large number of muscles that have not been investigated, more muscle-specific information could expand our understanding of functional deficits that develop with aging and help guide muscle-specific interventions to improve the quality of life of aging women and men.

Body Composition of Patients Undergoing Radical Cystectomy for Bladder Cancer: Sarcopenia, Low Psoas Muscle Index, and Myosteatosis Are Independent Risk Factors for Mortality

Background: We assessed a wide array of body composition parameters to identify those most relevant as prognostic tools for patients undergoing radical cystectomy (RC) due to bladder cancer (BC). Methods: In this retrospective, single-center study, preoperative computed tomography (CT) scans of 657 patients were measured at the level of the 3rd lumbar vertebra (L3) to determine common body composition indices including sarcopenia, myosteatosis, psoas muscle index (PMI), subcutaneous and visceral fat index (SFI and VFI), visceral-to-subcutaneous fat ratio (VSR), and visceral obesity. Predictors of overall survival (OS) and cancer-specific survival (CSS) were identified in univariate and multivariate survival analysis. Results: Sarcopenia and a low PMI were independently associated with shorter OS (Sarcopenia: HR 1.30; 95% CI 1.02–1.66; p = 0.04 and a low PMI: HR 1.32; 95% CI 1.02–1.70; p = 0.03) and CSS (Sarcopenia: HR 1.64; 95% CI 1.19–2.25; p < 0.01 and a low PMI: HR 1.41; 95% CI 1.02–1.96; p = 0.04). Myosteatosis, measured as decreasing average Hounsfield units of skeletal muscle, was an independent risk factor for OS (HR 0.98; 95% CI 0.97–1.00; p = 0.01) and CSS (HR 0.98; 95% CI 0.96–1.00; p < 0.05). The assessed adipose tissue indices were not significant predictors for OS and CSS. Conclusions: Sarcopenia, a low PMI, and myosteatosis are independent predictors for OS and CSS in patients undergoing radical cystectomy for bladder cancer.

Sarcopenia - Definition, Radiological Diagnosis, Clinical Significance

BACKGROUND

 Sarcopenia is an age-related syndrome characterized by a loss of muscle mass and strength. As a result, the independence of the elderly is reduced and the hospitalization rate and mortality increase. The onset of sarcopenia often begins in middle age due to an unbalanced diet or malnutrition in association with a lack of physical activity. This effect is intensified by concomitant diseases such as obesity or metabolic diseases including diabetes mellitus.

METHOD

 With effective preventative diagnostic procedures and specific therapeutic treatment of sarcopenia, the negative effects on the individual can be reduced and the negative impact on health as well as socioeconomic effects can be prevented. Various diagnostic options are available for this purpose. In addition to basic clinical methods such as measuring muscle strength, sarcopenia can also be detected using imaging techniques like dual X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI), and sonography. DXA, as a simple and cost-effective method, offers a low-dose option for assessing body composition. With cross-sectional imaging techniques such as CT and MRI, further diagnostic possibilities are available, including MR spectroscopy (MRS) for noninvasive molecular analysis of muscle tissue. CT can also be used in the context of examinations performed for other indications to acquire additional parameters of the skeletal muscles (opportunistic secondary use of CT data), such as abdominal muscle mass (total abdominal muscle area - TAMA) or the psoas as well as the pectoralis muscle index. The importance of sarcopenia is already well studied for patients with various tumor entities and also infections such as SARS-COV2.

RESULTS AND CONCLUSION

 Sarcopenia will become increasingly important, not least due to demographic changes in the population. In this review, the possibilities for the diagnosis of sarcopenia, the clinical significance, and therapeutic options are described. In particular, CT examinations, which are repeatedly performed on tumor patients, can be used for diagnostics. This opportunistic use can be supported by the use of artificial intelligence.

KEY POINTS

· Sarcopenia is an age-related syndrome with loss of muscle mass and strength.. · Early detection and therapy can prevent negative effects of sarcopenia.. · In addition to DEXA, cross-sectional imaging techniques (CT, MRI) are available for diagnostic purposes.. · The use of artificial intelligence (AI) offers further possibilities in sarcopenia diagnostics..

CITATION FORMAT

· Vogele D, Otto S, Sollmann N et al. Sarcopenia - Definition, Radiological Diagnosis, Clinical Significance. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1990-0201.

The correlation of muscle quantity and quality between all vertebra levels and level L3, measured with CT: An exploratory study

Introduction

In patients with cancer, low muscle mass has been associated with a higher risk of fatigue, poorer treatment outcomes, and mortality. To determine body composition with computed tomography (CT), measuring the muscle quantity at the level of lumbar 3 (L3) is suggested. However, in patients with cancer, CT imaging of the L3 level is not always available. Thus far, little is known about the extent to which other vertebra levels could be useful for measuring muscle status. In this study, we aimed to assess the correlation of the muscle quantity and quality between any vertebra level and L3 level in patients with various tumor localizations.

Methods

Two hundred-twenty Positron Emission Tomography (PET)-CT images of patients with four different tumor localizations were included: 1. head and neck (n = 34), 2. esophagus (n = 45), 3. lung (n = 54), and 4. melanoma (n = 87). From the whole body scan, 24 slices were used, i.e., one for each vertebra level. Two examiners contoured the muscles independently. After contouring, muscle quantity was estimated by calculating skeletal muscle area (SMA) and skeletal muscle index (SMI). Muscle quality was assessed by calculating muscle radiation attenuation (MRA). Pearson correlation coefficient was used to determine whether the other vertebra levels correlate with L3 level.

Results

For SMA, strong correlations were found between C1-C3 and L3, and C7-L5 and L3 (r = 0.72-0.95). For SMI, strong correlations were found between the levels C1-C2, C7-T5, T7-L5, and L3 (r = 0.70-0.93), respectively. For MRA, strong correlations were found between T1-L5 and L3 (r = 0.71-0.95).

Discussion

For muscle quantity, the correlations between the cervical, thoracic, and lumbar levels are good, except for the cervical levels in patients with esophageal cancer. For muscle quality, the correlations between the other levels and L3 are good, except for the cervical levels in patients with melanoma. If visualization of L3 on the CT scan is absent, the other thoracic and lumbar vertebra levels could serve as a proxy to measure muscle quantity and quality in patients with head and neck, esophageal, lung cancer, and melanoma, whereas the cervical levels may be less reliable as a proxy in some patient groups.

The effect of computed tomography parameters on sarcopenia and myosteatosis assessment: a scoping review

Computed tomography (CT) is a valuable assessment method for muscle pathologies such as sarcopenia, cachexia, and myosteatosis. However, several key underappreciated scan imaging parameters need consideration for both research and clinical use, specifically CT kilovoltage and the use of contrast material. We conducted a scoping review to assess these effects on CT muscle measures. We reviewed articles from PubMed, Scopus, and Web of Science from 1970 to 2020 on the effect of intravenous contrast material and variation in CT kilovoltage on muscle mass and density. We identified 971 articles on contrast and 277 articles on kilovoltage. The number of articles that met inclusion criteria for contrast and kilovoltage was 11 and 7, respectively. Ten studies evaluated the effect of contrast on muscle density of which nine found that contrast significantly increases CT muscle density (arterial phase 6-23% increase, venous phase 19-57% increase, and delayed phase 23-43% increase). Seven out of 10 studies evaluating the effect of contrast on muscle area found significant increases in area due to contrast (≤2.58%). Six studies evaluating kilovoltage on muscle density found that lower kilovoltage resulted in a higher muscle density (14-40% increase). One study reported a significant decrease in muscle area when reducing kilovoltage (2.9%). The use of contrast and kilovoltage variations can have dramatic effects on skeletal muscle analysis and should be considered and reported in CT muscle analysis research. These significant factors in CT skeletal muscle analysis can alter clinical and research outcomes and are therefore a barrier to clinical application unless better appreciated.

Current Approach to the Diagnosis of Sarcopenia in Heart Failure: A Narrative Review on the Role of Clinical and Imaging Assessments

Sarcopenia has been established as a predictor of poor outcomes in various clinical settings. It is particularly prevalent in heart failure, a clinical syndrome that poses significant challenges to health care worldwide. Despite this, sarcopenia remains overlooked and undertreated in cardiology practice. Understanding the currently proposed diagnostic process is paramount for the early detection and treatment of sarcopenia to mitigate downstream adverse health outcomes.

Body Composition as a Predictor of the Survival in Anal Cancer

Background and aim: Sarcopenia and body composition parameters such as visceral and subcutaneous adipose tissue and visceral-to-subcutaneous adipose tissue ratio have been shown to be relevant biomarkers for prognosis in patients with different types of cancer. However, these findings have not been well studied in anal cancer to date. Therefore, the aim of this study was to evaluate the prognostic value of different body composition parameters in patients undergoing radiation therapy for the treatment of anal cancer with curative intent. Material and Methods: After approval by the institutional ethical committee, we retrospectively identified 81 patients in our local registry, who received radical intensity-modulated radiotherapy for the management of anal squamous cell cancer (ASCC). Clinical information, including body mass index (BMI), survival, and toxicities outcome, were retrieved from the local hospital registry. Based on the pre-therapeutic computer tomography (CT), we measured the total psoas muscle area, visceral adipose tissue area (VAT), subcutaneous adipose tissue area (SAT), and visceral-to-subcutaneous adipose tissue area ratio (VSR). In addition to the classical prognostic factors as T-stage, N-stage, gender, and treatment duration, we analyzed the impact of body composition on the prognosis in univariate and multivariate analyses. Results: Sarcopenia was not associated with increased mortality in anal cancer patients, whereas increased BMI (≥27 kg/m2) and VSR (≥0.45) were significantly associated with worsened overall survival and cancer-specific survival in both univariate and multivariate analyses. VSR-not BMI-was statistically higher in males. Sarcopenia and VSR ≥ 0.45 were associated with advanced T-stages. None of the body composition parameters resulted in a significant increase in treatment-related toxicities. Conclusion: BMI and visceral adiposity are independent prognostic factors for the survival of patients with anal cancer. Measurements to treat adiposity at the time of diagnosis may be needed to improve the survival outcomes for the affected patients.

Sarcopenia as a Predictor of Short- and Long-Term Outcomes in Patients Surgically Treated for Malignant Pleural Mesothelioma

Surgery for malignant pleural mesothelioma (MPM) should be reserved only for patients who have a good performance status. Sarcopenia, a well-known predictor of poor outcomes after surgery, is still underinvestigated in MPM. The aim of this study is to evaluate the role of sarcopenia as a predictor of short-and long-term outcomes in patients surgically treated for MPM. In our analysis, we included patients treated with a cytoreductive intent in a multimodality setting, with both pre- and post-operative CT scans without contrast available. We excluded those in whom a complete macroscopic resection was not achieved. Overall, 86 patients were enrolled. Sarcopenia was assessed by measuring the mean muscular density of the bilateral paravertebral muscles (T12 level) on pre-and post-operative CTs; a threshold value of 30 Hounsfield Units (HU) was identified. Sarcopenia was found pre-operatively in 57 (66%) patients and post-operatively in 61 (74%). Post-operative sarcopenic patients had a lower 3-year overall survival (OS) than those who were non-sarcopenic (34.9% vs. 57.6% p = 0.03). Pre-operative sarcopenia was significantly associated with a higher frequency of post-operative complications (65% vs. 41%, p = 0.04). The evaluation of sarcopenia, through a non-invasive method, would help to better select patients submitted to surgery for MPM in a multimodality setting.

MRI biomarker of muscle composition is associated with severity of pelvic organ prolapse

BACKGROUND

The pathophysiology of pelvic organ prolapse is largely unknown. We hypothesized that reduced muscle mass on magnetic resonance defecography (MRD) is associated with increased pelvic floor laxity. The aim of this study was to compare the psoas and puborectalis muscle mass composition and cross-sectional area among patients with or without pelvic laxity.

METHODS

An observational retrospective study was conducted on women > age 18 years old who had undergone MRD for pelvic floor complaints from January 2020 to December 2020 at Stanford Pelvic Health Center. Pelvic floor laxity, pelvic organ descent, and rectal prolapse were characterized by standard measurements on MRD and compared to the psoas (L4 level) and puborectalis muscle index (cross-sectional area adjusted by height) and relative fat fraction, quantified by utilizing a 2-point Dixon technique. Regression analysis was used to quantify the association between muscle characteristics and pelvic organ measurements.

RESULTS

The psoas fat fraction was significantly elevated in patients with abnormally increased resting and strain H and M lines (p < 0.05) and increased with rising grades of Oxford rectal prolapse (p = 0.0001), uterovaginal descent (p = 0.001) and bladder descent (p = 0.0005). In multivariate regression analysis, adjusted for age and body mass index, the psoas fat fraction (not muscle index) was an independent risk factor for abnormal strain H and M line; odds ratio (95% confidence interval) of 17.8 (2-155.4) and 18.5 (1.3-258.3) respectively, and rising Oxford grade of rectal prolapse 153.9 (4.4-5383) and bladder descent 12.4 (1.5-106). Puborectalis fat fraction was increased by rising grades of Oxford rectal prolapse (p = 0.0002).

CONCLUSIONS

Severity of pelvic organ prolapse appears to be associated with increasing psoas muscle fat fraction, a biomarker for reduced skeletal muscle mass. Future prospective research is needed to determine if sarcopenia may predict postsurgical outcomes after pelvic organ prolapse repair.

Muscle Area and Density Assessed by Abdominal Computed Tomography in Healthy Adults: Effect of Normal Aging and Derivation of Reference Values

BACKGROUND

A growing body of evidence has demonstrated the prognostic value of skeletal muscle area and quality measured by computed tomography (CT) as biomarkers of sarcopenia and frailty. However, there exists little data in normal healthy subjects to inform reference values and determine the effects of advancing age and sex on CT muscle parameters.

METHODS

Abdominal CT images of patients (20-80 years of age) presenting to the emergency department with benign abdominal symptoms and no significant medical comorbidities were retrospectively collected from 2014 to 2017. Psoas and abdominal wall muscle area (PMA, WMA) and density (PMD, WMD) at the level of the L4 vertebrae were measured with the CoreSlicer.com web app. The normal reference range was computed by non-parameteric 2.5th and 97.5th percentiles stratified by sex and restricted by age to the younger subgroup (20-39 years of age).

RESULTS

The cohort consisted of 390 otherwise healthy patients (162 males, 228 females). The lower reference range for PMA was <22.0 cm2 in males and <11.1 cm2 in females, and for WMA was <112.2 cm2 in males and <75.6 cm2 in females. There was a graded decline observed in PMA and WMA among older compared to younger adults (especially ≥60 years of age) (P<0.001) and among females compared to males (P<0.001). There was also a graded decline observed in PMD and WMD among older compared to younger adults (P<0.001), irrespective of sex.

CONCLUSION

This study has defined the normal reference values and age-associated down-trend for CT muscle parameters at L4 in a healthy population using an accessible web-based software, which help contextualize and interpret these imaging biomarkers of sarcopenia in clinical care.

Sarcopenia in Children with Solid Organ Tumors: An Instrumental Era

Sarcopenia has recently been studied in both adults and children and was found to be a prognostic marker for adverse outcome in a variety of patient groups. Our research showed that sarcopenia is a relevant marker in predicting outcome in children with solid organ tumors, such as hepatoblastoma and neuroblastoma. This was especially true in very ill, high-risk groups. Children with cancer have a higher likelihood of ongoing loss of skeletal muscle mass due to a mismatch in energy intake and expenditure. Additionally, the effects of cancer therapy, hormonal alterations, chronic inflammation, multi-organ dysfunction, and a hypermetabolic state all contribute to a loss of skeletal muscle mass. Sarcopenia seems to be able to pinpoint this waste to a high degree in a new and objective way, making it an additional tool in predicting and improving outcome in children. This article focuses on the current state of sarcopenia in children with solid organ tumors. It details the pathophysiological mechanisms behind sarcopenia, highlighting the technical features of the available methods for measuring muscle mass, strength, and function, including artificial intelligence (AI)-based techniques. It also reviews the latest research on sarcopenia in children, focusing on children with solid organ tumors.

Reference values of skeletal muscle area for diagnosis of sarcopenia using chest computed tomography in Asian general population

BACKGROUND

Diagnostic cutoff points for sarcopenia in chest computed tomography (CT) have not been established although CT is widely used for investigating skeletal muscles. This study aimed to determine reference values for sarcopenia of thoracic skeletal muscles acquired from chest CT scans and to analyse variables related to sarcopenia using the cutoff values determined in a general Asian population.

METHODS

We retrospectively reviewed chest CT scans of 4470 participants (mean age 54.8 ± 9.9 years, 65.8% male) performed at a check-up centre in South Korea (January 2016-August 2017). To determine cutoffs, 335 participants aged 19-39 years (mean age 35.2 ± 3.6 years, 75.2% male) were selected as the healthy and younger reference group, and 4135 participants aged ≥40 years (mean age 56.4 ± 8.4 years, 65.1% male) were selected as the study group. We measured the following: cross-sectional area (CSA) of the pectoralis, intercostalis, paraspinal, serratus, and latissimus muscles at the 4^th vertebral region (T4_CSA ); T4_CSA divided by height² (T4MI); pectoralis muscle area (PM_CSA ); and PM_CSA divided by height² (PMI) at the 4^th vertebral region. Sarcopenia cutoff was defined as sex-specific values of less than -2 SD below the mean from the reference group.

RESULTS

In the reference group, T4_CSA , T4MI, PM_CSA , and PMI cutoffs for sarcopenia were 100.06cm² , 33.69cm² /m² , 29.00cm² , and 10.17cm² /m² in male, and 66.93cm² , 26.01cm² /m² , 18.29cm² , and 7.31cm² /m² in female, respectively. The prevalence of sarcopenia in the study group measured with T4_CSA , T4MI, PM_CSA and PMI cutoffs were 11.4%, 8.7%, 8.5%, and 10.1%, respectively. Correlations were observed between appendicular skeletal mass divided by height² measured by bioelectrical impedance analysis (BIA) and T4_CSA (r = 0.82; P < 0.001)/T4MI (r = 0.68; P < 0.001), and ASM/height² measured by BIA and PM_CSA (r = 0.72; P < 0.001)/PMI (r = 0.63; P < 0.001). In the multivariate logistic regression models, sarcopenia defined by T4_CSA /T4MI were related to age [odds ratio (95% confidence interval), P-values: 1.09 (1.07-1.11), <0.001/1.05 (1.04-1.07), <0.001] and diabetes [1.60 (1.14-2.25), 0.007/1.47 (1.01-2.14), 0.043]. Sarcopenia defined by PM_CSA /PMI were related to age [1.09 (1.08-1.10), <0.001/1.05 (1.03-1.06), <0.001], male sex [0.23 (0.18-0.30), <0.001/0.47 (0.32-0.71), <0.001], diabetes [2.30 (1.73-3.05), <0.001/1.63 (1.15-2.32), 0.007], history of cancer [2.51 (1.78-3.55), <0.001/1.61 (1.04-2.48), 0.033], and sufficient physical activity [0.67 (0.50-0.89), 0.007/0.74 (0.56-0.99), 0.042].

CONCLUSIONS

The reference cutoff values of a general population reported here will enable sex-specific standardization of thoracic muscle mass quantification and sarcopenia assessment.

The Value of Artificial Intelligence-Assisted Imaging in Identifying Diagnostic Markers of Sarcopenia in Patients with Cancer

Sarcopenia is defined as the loss of skeletal muscle mass and muscle function. It is common in patients with malignancies and often associated with adverse clinical outcomes. The presence of sarcopenia in patients with cancer is determined by body composition, and recently, radiologic technology for the accurate estimation of body composition is under development. Artificial intelligence- (AI-) assisted image measurement facilitates the detection of sarcopenia in clinical practice. Sarcopenia is a prognostic factor for patients with cancer, and confirming its presence helps to recognize those patients at the greatest risk, which provides a guide for designing individualized cancer treatments. In this review, we examine the recent literature (2017-2021) on AI-assisted image assessment of body composition and sarcopenia, seeking to synthesize current information on the mechanism and the importance of sarcopenia, its diagnostic image markers, and the interventions for sarcopenia in the medical care of patients with cancer. We concluded that AI-assisted image analysis is a reliable automatic technique for segmentation of abdominal adipose tissue. It has the potential to improve diagnosis of sarcopenia and facilitates identification of oncology patients at the greatest risk, supporting individualized prevention planning and treatment evaluation. The capability of AI approaches in analyzing series of big data and extracting features beyond manual skills would no doubt progressively provide impactful information and greatly refine the standard for assessing sarcopenia risk in patients with cancer.

CT evaluation for sarcopenia involving the psoas and paravertebral muscles in patients with total hip arthroplasty

BACKGROUND

Computed tomography (CT) has been validated in diagnosing sarcopenia in various clinical conditions.

AIM

To evaluate the core abdominal muscles in terms of sarcopenia in patients with total hip arthroplasty (THA) with and without complication.

METHODS

Retrospective analysis of patients with a pelvic CT revealed 145 consecutive patients with THA. Also, 118 consecutive cases with normal CT scans constituted the control group. The area and density measurements of bilateral psoas (PSA, psoas area; PSD, psoas density) and paravertebral (PVA, paravertebral area; PVD, paravertebral density) muscles were performed at the level of L3 or L4 vertebrae regardless of prosthesis side. All measurements were evaluated in normal cases and in patients with THA, as well as in patients with complicated prostheses.

RESULTS

In the whole population and subgroup of patients with bilateral THA, bilateral PSA, PSD, and PVD but not the PVA were lower in patients with THA compared to controls (all p < 0.01). In patients with unilateral prostheses, ipsilateral PSA, PSD, and bilateral PVD but not the PVA were lower compared to controls (all p < 0.01). Furthermore, in patients with unilateral prostheses with complication, only ipsilateral PSD was lower compared to patients with unilateral prostheses without complication (all p < 0.05) and in patients with bilateral prostheses with complication, bilateral PSA, PSD, and PVD but not the PVA were lower compared to patients with bilateral prostheses without complication (all p < 0.05).

CONCLUSION

Sarcopenia indicated by the area and density measurements of core abdominal muscles can be associated with the presence and complication of hip prostheses.

Sarcopenia in rheumatic disorders: what the radiologist and rheumatologist should know

Sarcopenia is defined as the loss of muscle mass, strength, and function. Increasing evidence shows that sarcopenia is common in patients with rheumatic disorders. Although sarcopenia can be diagnosed using bioelectrical impedance analysis or DXA, increasingly it is diagnosed using CT, MRI, and ultrasound. In rheumatic patients, CT and MRI allow "opportunistic" measurement of body composition, including surrogate markers of sarcopenia, from studies obtained during routine patient care. Recognition of sarcopenia is important in rheumatic patients because sarcopenia can be associated with disease progression and poor outcomes. This article reviews how opportunistic evaluation of sarcopenia in rheumatic patients can be accomplished and potentially contribute to improved patient care.

Healthy US population reference values for CT visceral fat measurements and the impact of IV contrast, HU range, and spinal levels

Measurements of visceral adipose tissue cross-sectional area and radiation attenuation from computed tomography (CT) scans provide useful information about risk and mortality. However, scan protocols vary, encompassing differing vertebra levels and utilizing differing phases of contrast enhancement. Furthermore, fat measurements have been extracted from CT using different Hounsfield Unit (HU) ranges. To our knowledge, there have been no large studies of healthy cohorts that reported reference values for visceral fat area and radiation attenuation at multiple vertebra levels, for different contrast phases, and using different fat HU ranges. Two-phase CT scans from 1,677 healthy, adult kidney donors (age 18–65) between 1999 and 2017, previously studied to determine healthy reference values for skeletal muscle measures, were utilized. Visceral adipose tissue cross-sectional area (VFA) and radiation attenuation (VFRA) measures were quantified using axial slices at T10 through L4 vertebra levels. T-tests were used to compare males and females, while paired t-tests were conducted to determine the effect (magnitude and direction) of (a) contrast enhancement and (b) different fat HU ranges on each fat measure at each vertebra level. We report the means, standard deviations, and effect sizes of contrast enhancement and fat HU range. Male and female VFA and VFRA were significantly different at all vertebra levels in both contrast and non-contrast scans. Peak VFA was observed at L4 in females and L2 in males, while peak VFRA was observed at L1 in both females and males. In general, non-contrast scans showed significantly greater VFA and VFRA compared to contrast scans. The average paired difference due to contrast ranged from 1.6 to − 8% (VFA) and 3.2 to − 3.0% (VFRA) of the non-contrast value. HU range showed much greater differences in VFA and VFRA than contrast. The average paired differences due to HU range ranged from − 5.3 to 22.2% (VFA) and − 5.9 to 13.6% (VFRA) in non-contrast scans, and − 4.4 to 20.2% (VFA) and − 4.1 to 12.6% (VFRA) in contrast scans. The − 190 to − 30 HU range showed the largest differences in both VFA (10.8% to 22.2%) and VFRA (7.6% to 13.6%) compared to the reference range (− 205 to − 51 HU). Incidentally, we found that differences in lung inflation result in very large differences in visceral fat measures, particularly in the thoracic region. We assessed the independent effects of contrast presence and fat HU ranges on visceral fat cross-sectional area and mean radiation attenuation, finding significant differences particularly between different fat HU ranges. These results demonstrate that CT measurements of visceral fat area and radiation attenuation are strongly dependent upon contrast presence, fat HU range, sex, breath cycle, and vertebra level of measurement. We quantified contrast and non-contrast reference values separately for males and females, using different fat HU ranges, for lumbar and thoracic CT visceral fat measures at multiple vertebra levels in a healthy adult US population.

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

BACKGROUND

Skeletal muscle metrics on computed tomography (CT) correlate with clinical and patient-reported outcomes. We hypothesize that aggregating skeletal muscle measurements from multiple vertebral levels and skeletal muscle gauge (SMG) better predict outcomes than skeletal muscle radioattenuation (SMRA) or -index (SMI) at a single vertebral level.

METHODS

We performed a secondary analysis of prospectively collected clinical (overall survival, hospital readmission, time to unplanned hospital readmission or death, and readmission or death within 90 days) and patient-reported outcomes (physical and psychological symptom burden captured as Edmonton Symptom Assessment Scale and Patient Health Questionnaire) of patients with advanced cancer who experienced an unplanned admission to Massachusetts General Hospital from 2014 to 2016. First, we assessed the correlation of skeletal muscle cross-sectional area, SMRA, SMI, and SMG at one or more of the following thoracic (T) or lumbar (L) vertebral levels: T5, T8, T10, and L3 on CT scans obtained ≤50 days before index assessment. Second, we aggregated measurements across all available vertebral levels using percentile-based averaging (PBA) to create the average percentile. Third, we constructed one regression model adjusted for age, sex, sociodemographic factors, cancer type, body mass index, and intravenous contrast for each combination of (i) vertebral level and average percentile, (ii) muscle metrics (SMRA, SMI, & SMG), and (iii) clinical and patient-reported outcomes. Fourth, we compared the performance of vertebral levels and muscle metrics by ranking otherwise identical models by concordance statistic, number of included patients, coefficient of determination, and significance of muscle metric.

RESULTS

We included 846 patients (mean age: 63.5 ± 12.9 years, 50.5% males) with advanced cancer [predominantly gastrointestinal (32.9%) or lung (18.9%)]. The correlation of muscle measurements between vertebral levels ranged from 0.71 to 0.84 for SMRA and 0.67 to 0.81 for SMI. The correlation of individual levels with the average percentile was 0.90-0.93 for SMRA and 0.86-0.92 for SMI. The intrapatient correlation of SMRA with SMI was 0.21-0.40. PBA allowed for inclusion of 8-47% more patients than any single-level analysis. PBA outperformed single-level analyses across all comparisons with average ranks 2.6, 2.9, and 1.6 for concordance statistic, coefficient of determination, and significance (range 1-5, μ = 3), respectively. On average, SMG outperformed SMRA and SMI across outcomes and vertebral levels: the average rank of SMG was 1.4, 1.4, and 1.4 for concordance statistic, coefficient of determination, and significance (range 1-3, μ = 2), respectively.

CONCLUSIONS

Multivertebral level skeletal muscle analyses using PBA and SMG independently and additively outperform analyses using individual levels and SMRA or SMI.

Two-dimensional CT measurements enable assessment of body composition on head and neck CT

OBJECTIVES

The aim of this study was to evaluate whether simple 2D measurements in axial slices of head and neck CT examinations correlate with generally established measurements of body composition in abdominal CT at the height of the third lumbar vertebra and thus allow for an estimation of muscle and fat masses.

METHODS

One hundred twenty-two patients who underwent concurrent CT of the head and neck and the abdomen between July 2016 and July 2020 were retrospectively included. For a subset of 30 patients, additional bioelectrical impedance analysis (BIA) was available. Areas of paraspinal muscles at the height of the third (C3) and fifth cervical vertebrae (C5) as well as the total cross-sectional area at the height of C3 and at the submandibular level were correlated with the results of abdominal measurements and BIA. Furthermore, intra- and interreader variabilities of all measurements were assessed.

RESULTS

Regarding adipose tissue, good correlations were found between the total cross-sectional area of the patient's body at the submandibular level and at the height of C3 between both abdominal measurements and BIA results (r = 0.8-0.92; all p < 0.001). Regarding muscle, the total paraspinal muscle area at the height of C3 and C5 showed strong correlations with abdominal measurements and moderate to strong correlations with BIA results (r = 0.44-0.80; all p < 0.001), with the muscle area on C5 yielding slightly higher correlations.

CONCLUSIONS

Body composition information can be obtained with comparable reliability from head and neck CT using simple biplanar measurements as from abdominal CT.

KEY POINTS

• The total paraspinal muscle area at the height of C3 and C5 correlates strongly with abdominal muscle mass. • The total cross-sectional area at the submandibular level and at the height of C3 shows good correlations with abdominal fat mass. • The described measurements facilitate a rapid, opportunistic assessment of relevant body composition parameters.

Sarcopenia: imaging assessment and clinical application

Sarcopenia is a progressive, generalized skeletal muscle disorder characterized by reduction of muscle mass and strength. It is associated with increased adverse outcomes including falls, fractures, physical disability, and mortality, particularly, in elderly patients. Nowadays, sarcopenia has become a specific imaging biomarker able to predict clinical outcomes of patients. Muscle fibre reduction has shown to be an unfavourable pre-operative predictive factor in patients with cancer, and is associated with worse clinical outcomes in terms of postoperative complications, morbidity, mortality, and lower tolerance of chemoradiation therapy. Several imaging modalities, including dual-energy X-ray absorptiometry, CT, MRI, and US can be used to estimate muscle mass and quality to reach the diagnosis of sarcopenia. This article reviews the clinical implications of sarcopenia, how this condition can be assessed through different imaging modalities, and future perspectives of imaging of sarcopenia.

Association of SARC-F Score and Rockwood Clinical Frailty Scale with CT-Derived Muscle Mass in Patients with Aortic Aneurysms

OBJECTIVES

Patients with aortic aneurysms (AA) are often co-morbid and susceptible to frailty. Low core muscle mass has been used as a surrogate marker of sarcopenia and indicator of frailty. This study aimed to assess association between core muscle mass with sarcopenia screening tool SARC-F and Clinical Frailty Scale (CFS) in patients with AA.

METHODS

Prospective audit of patients in pre-operative aortic clinic between 01/07/2019-31/01/2020 including frailty assessment using Rockwood CFS and sarcopenia screening using SARC-F questionnaire. Psoas and sartorius muscle area were measured on pre-operative CT scans and adjusted for height. Association was assessed using Spearman's rank correlation coefficient.

RESULTS

Of 84 patients assessed, median age was 75 years [72,82], 84.5% were men, 65.5% were multimorbid and 63.1% had polypharmacy. Nineteen percent were identified as frail (CFS score >3) and 6.1% positively screened for sarcopenia (SARC-F score 4 or more). Median psoas area (PMA) at L3 was 5.6cm2/m2 [4.8,6.6] and L4 was 7.4cm2/m2 [6.3,8.6]. Median sartorius area (SMA) was 1.8 cm2/m2 [1.5,2.2]. CFS demonstrated weak but statistically significant negative correlation with height-adjusted PMA at L3 (r=-0.25, p=0.034) but not at L4 (r=-0.23, p=0.051) or with SMA (r=-0.22, p=0.065). No association was observed between SARC-F score and PMA or SMA (L3 PMA r=-0.015, p=0.9; L4 PMA r=-0.0014, p= 0.99; SMA r=-0.051, p=0.67).

CONCLUSION

CFS showed higher association with CT-derived muscle mass than SARC-F. Comprehensive pre-operative risk-stratification tools which incorporate frailty assessment and body composition analysis may assist in decision making for surgery and allow opportunity for pre-habilitation.

Thoracic skeletal muscle quantification using computed tomography and prognosis of elderly ICU patients

In elderly ICU patients, the prevalence of skeletal muscle loss is high. Longitudinal effect of thoracic muscles, especially in elderly ICU patients, are unclear although skeletal muscle loss is related with the short- and long-term outcomes. This study aimed to evaluate whether pectoralis muscle mass loss could be a predictor of prognosis in elderly ICU patients. We retrospectively evaluated 190 elderly (age > 70 years) patients admitted to the ICU. We measured the cross-sectional area (CSA) of the pectoralis muscle (PM_CSA) at the fourth vertebral region. CT scans within two days before ICU admission were used for analysis. Mortality, prolonged mechanical ventilation, and longitudinal changes in Sequential Organ Failure Assessment (SOFA) scores were examined. PM_CSA below median was significantly related with prolonged ventilation (odds ratio 2.92) and a higher SOFA scores during the ICU stay (estimated mean = 0.94). PM_CSA below median was a significant risk for hospital mortality (hazards ratio 2.06). In elderly ICU patients, a low ICU admission PM_CSA was associated with prolonged ventilation, higher SOFA score during the ICU stay, and higher mortality. Adding thoracic skeletal muscle CSA at the time of ICU admission into consideration in deciding the therapeutic intensity in elderly ICU patients may help in making medical decisions.

A correction score to compare aortic calcification in contrast enhanced and non-contrast measurements from computed tomography scans

BACKGROUND

Aortic wall calcification shows strong promise as a cardiovascular risk factor. While useful for visual enhancement of vascular tissue, enhancement creates heterogeneity between scans with and without contrast. We evaluated the relationship between aortic calcification in routine abdominal computed tomography scans (CT) with and without contrast.

METHODS

Inclusion was limited to those with abdominal CT-scans with and without contrast enhancement within 120 days. Analytic Morphomics, a semi-automated computational image processing system, was used to provide standardized, granular, anatomically indexed measurements of aortic wall calcification from abdominal CT-scans. Aortic calcification area (ACA) and aortic wall calcification percent (ACP) and were the outcomes of interest. Multiple linear regression was used to evaluate the relationship of aortic measurements. Models were further controlled for age and sex. Stratification of measurements by vertebral level was also performed.

RESULTS

A positive association was observed for non-contrast calcification in ACP β 0.74 (95% CI 0.72, 0.76) and ACA β 0.44 (95% 0.43, 0.45). Stratified results demonstrated the highest coefficient of determination at L2 for percent and L3 for area models [R² 0.91 (ACP) 0.74 (ACA)]. Adjusted lumber-level associations between non-contrast and contrast measurements ranged from (β 0.69-0.82) in ACP and (β 0.37-0.54) in ACA.

CONCLUSION

A straightforward correction score for comparison of abdominal aortic calcification measurements in contrast-enhanced and non-contrast scans is discussed. Correction of aortic calcification from CT scans can reduce scan heterogeneity and will be instrumental in creating larger cardiovascular cohorts as well as cardiovascular risk surveillance programs.

Developing a morphomics framework to optimize implant site-specific design parameters for islet macroencapsulation devices

Delivering a clinically impactful cell number is a major design challenge for cell macroencapsulation devices for Type 1 diabetes. It is important to understand the transplant site anatomy to design a device that is practical and that can achieve a sufficient cell dose. We identify the posterior rectus sheath plane as a potential implant site as it is easily accessible, can facilitate longitudinal monitoring of transplants, and can provide nutritive support for cell survival. We have investigated this space using morphomics across a representative patient cohort (642 participants) and have analysed the data in terms of gender, age and BMI. We used a shape optimization process to maximize the volume and identified that elliptical devices achieve a clinically impactful cell dose while meeting device manufacture and delivery requirements. This morphomics framework has the potential to significantly influence the design of future macroencapsulation devices to better suit the needs of patients.

Quality Matters as Much as Quantity of Skeletal Muscle: Clinical Implications of Myosteatosis in Cardiometabolic Health

Although age-related changes in skeletal muscles are closely associated with decreases in muscle strength and functional decline, their associations with cardiometabolic diseases in the literature are inconsistent. Such inconsistency could be explained by the fact that muscle quality-which is closely associated with fatty infiltration of the muscle (i.e., myosteatosis)-is as important as muscle quantity in cardiometabolic health. However, muscle quality has been less explored compared with muscle mass. Moreover, the standard definition of myosteatosis and its assessment methods have not been established yet. Recently, some techniques using single axial computed tomography (CT) images have been introduced and utilized in many studies, as the mass and quality of abdominal muscles could be measured opportunistically on abdominal CT scans obtained during routine clinical care. Yet, the mechanisms by which myosteatosis affect metabolic and cardiovascular health remain largely unknown. In this review, we explore the recent advances in the assessment of myosteatosis and its changes associated with aging. We also review the recent literature on the clinical implication of myosteatosis by focusing on metabolic and cardiovascular diseases. Finally, we discuss the challenges and unanswered questions that need addressing to set myosteatosis as a therapeutic target for the prevention or treatment of cardiometabolic diseases.

Diagnosing sarcopenia and myosteatosis based on chest computed tomography images in healthy Chinese adults

BACKGROUND

Measuring muscle mass and muscle quality based on chest Computed Tomography (CT) images would facilitate sarcopenia and myosteatosis research. We aimed (1) to measure muscle mass and myosteatosis based on chest CT images at the 12th thoracic vertebra level and compare the relevant indicators with whole-body skeletal muscle mass (BSM) and whole-body fat mass (BFM) measured by bioelectrical impedance analysis; and (2) to determine the cut-off points of these indicators for diagnosing sarcopenia or myosteatosis in healthy Chinese adults.

METHODS

Chest CT images were analyzed using a segmentation software. Skeletal muscle area (SMA), skeletal muscle radiodensity (SMD), and intermuscular adiposity tissue (IMAT) were measured. Skeletal muscle indices (SMIs) and IMAT/SMA ratio were calculated.

RESULTS

We included 569 participants. SMA, SMA/height2, and SMA/BMI were strongly and positively correlated with BSM (r = 0.90, 0.72, and 0.69, respectively, all p < 0.001); whereas SMA/weight was moderately and positively correlated with BSM (r = 0.38, p < 0.001). IMAT and IMAT/SMA were strongly and positively correlated with BFM (r = 0.67 and 0.58, respectively, both p < 0.001). SMD was moderately and negatively correlated with BFM (r = - 0.40, p < 0.001). We suggest SMA/height2 (< 25.75 cm2/m2 in men and < 20.16 cm2/m2 in women) for diagnosing sarcopenia and SMD (< 37.42 HU in men and < 33.17 HU in women) or IMAT (> 8.72 cm2 in men and > 4.58 cm2 in women) for diagnosing myosteatosis.

CONCLUSIONS

Muscle mass indicators (SMA and SMIs) and muscle quality indicators (SMD, IMAT, and IMAT/SMA) measured by chest CT images are valuable for diagnosing sarcopenia and myosteatosis, respectively.

Automated Measurements of Body Composition in Abdominal CT Scans Using Artificial Intelligence Can Predict Mortality in Patients With Cirrhosis

Body composition measures derived from already available electronic medical records (computed tomography [CT] scans) can have significant value, but automation of measurements is needed for clinical implementation. We sought to use artificial intelligence to develop an automated method to measure body composition and test the algorithm on a clinical cohort to predict mortality. We constructed a deep learning algorithm using Google's DeepLabv3+ on a cohort of de-identified CT scans (n = 12,067). To test for the accuracy and clinical usefulness of the algorithm, we used a unique cohort of prospectively followed patients with cirrhosis (n = 238) who had CT scans performed. To assess model performance, we used the confusion matrix and calculated the mean accuracy of 0.977 ± 0.02 (0.975 ± 0.018 for the training and test sets, respectively). To assess for spatial overlap, we measured the mean intersection over union and mean boundary contour scores and found excellent overlap between the manual and automated methods with mean scores of 0.954 ± 0.030, 0.987 ± 0.009, and 0.948 ± 0.039 (0.983 ± 0.013 for the training and test set, respectively). Using these automated measurements, we found that body composition features were predictive of mortality in patients with cirrhosis. On multivariate analysis, the addition of body composition measures significantly improved prediction of mortality for patients with cirrhosis over Model for End-Stage Liver Disease alone (P < 0.001). Conclusion: The measurement of body composition can be automated using artificial intelligence and add significant value for incidental CTs performed for other clinical indications. This is proof of concept that this methodology could allow for wider implementation into the clinical arena.

Predicting outcomes of abdominal surgical emergencies in the elderly population using a CT muscle gauge

BACKGROUND

Frailty has been shown to be an independent negative predictor of surgical outcomes in geriatric patients. Traditional measurements of muscle strength and mass are impractical in emergency settings, and computed tomography (CT)-measured skeletal muscle mass has been proposed as an alternative. However, the cutoff values for low muscle mass are still unknown, and their impact on abdominal emergencies in the elderly population is unclear.

METHODS

A total of 462 young trauma patients aged 18-40 years were analyzed to establish sex-specific reference cutoff values for the CT-measured muscle index (MI) and muscle gauge (MG) values. The impacts of low MI and MG values were investigated in 1192 elderly patients (aged ≥ 65 years) undergoing abdominal surgery.

RESULTS

The sex-specific cutoff values for MI and MG were determined by adopting European Working Group on Sarcopenia in Older People 2 guidelines. The correlation between MG and aging was significantly stronger than that between MI and ageing. With regard to the MG, the L4 psoas muscle gauge (L4 PMG) was further investigated in an elderly cohort owing to its high predictive value and ease of use in the clinical setting. A low L4 PMG value was an independent risk factor for overall complications and mortality in elderly patients with abdominal emergencies.

CONCLUSION

The current study was the largest study investigating the correlations between MG values and aging in the Asian population. A low L4 PMG value may help surgeons during preoperative decision making regarding geriatric patients with abdominal emergencies.

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

OBJECTIVE

To determine the relationship between CT-derived muscle metrics and standardized metrics of sarcopenia in patients undergoing routine CT imaging.

MATERIALS AND METHODS

Data collected in 443 consecutive patients included body CT, grip strength, usual gait speed, and responses to SARC-F and FRAIL scale questionnaires. Functional and clinical metrics of sarcopenia were acquired at the time of CT. Metrics were analyzed using the diagnostic framework of the European Working Group on Sarcopenia in Older People (EWGSOP2). The skeletal muscle index (SMI) and skeletal muscle density (SMD) were measured at the T12 and L3 levels. Statistical methods include linear prediction models and ROC analysis.

RESULTS

T12-SMD and L3-SMD in women and T12-SMD and L3-SMI in men show weak but significant (p < 0.05) predictive value for gait speed, after adjusting for subject age and body mass index. The prevalence of abnormal CT SMI at T12 and L3 was 29% and 71%, respectively, corresponding to prevalences of confirmed sarcopenia by EWGSOP2 of 10% and 15%, respectively. The agreement of abnormal SARC-F and FRAIL scale screening and EWGSOP2 confirmed sarcopenia was slight to fair (kappa: 0.20-0.28). CT cutpoints, based on EWGSOP2 criteria for abnormal grip strength or gait speed, are generally lower than cutpoints based on normative population data.

CONCLUSION

Collection of clinical and functional sarcopenia information at the point of imaging care can be accomplished quickly and safely. CT-derived muscle metrics show convergent validity with gait speed. Only a minority of subjects with low CT metrics have confirmed sarcopenia by EWGSOP2 definition.

Optimal body size adjustment of L3 CT skeletal muscle area for sarcopenia assessment

Measurements of skeletal muscle cross-sectional area (SMA) at the level of the third lumbar (L3) vertebra derived from clinical computed tomography (CT) scans are commonly used in assessments of sarcopenia, the loss of skeletal muscle mass and function associated with aging. As SMA is correlated with height and Body Mass Index (BMI), body size adjustment is necessary to fairly assess sarcopenic low muscle mass in individuals of different height and BMI. The skeletal muscle index, a widely used measure, adjusts for height as [Formula: see text] but uses no BMI adjustment. There is no agreed upon standard for body size adjustment. We extracted L3 SMA using non-contrast-enhanced CT scans from healthy adults, split into 'Under-40' and 'Over-40' cohorts. Sex-specific allometric analysis showed that height to the power of one was the optimal integer coefficient for height adjusted SMA in both males and females. We computed two height-adjusted measures [Formula: see text] and [Formula: see text], comparing their Pearson correlations versus age, height, weight, and BMI separately by sex and cohort. Finally, in the 'Under-40' cohort, we used linear regression to convert each height-adjusted measure into a z-score ([Formula: see text], [Formula: see text]) adjusted for BMI. [Formula: see text] was less correlated with height in both males and females ([Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text]) than [Formula: see text] ([Formula: see text] and [Formula: see text], [Formula: see text]). [Formula: see text] was uncorrelated with BMI and weight, and minimally correlated with height in males and females ([Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text]). The final [Formula: see text] equation was: [Formula: see text], where [Formula: see text], [Formula: see text], [Formula: see text], and sex = 1 if male, 0 if female. We propose [Formula: see text] for optimal height adjustment and the [Formula: see text] score for optimal height and BMI adjustment. By minimizing correlations with height and BMI, the [Formula: see text] score produces unbiased assessments of relative L3 skeletal muscle area across the full range of body sizes.