Age-related changes in muscle quality and development of diagnostic cutoff points for myosteatosis in lumbar skeletal muscles measured by CT scan

Association between atherogenic dyslipidemia and muscle quality defined by myosteatosis

Background

Myosteatosis, ectopic fat accumulation in skeletal muscle, is a crucial component of sarcopenia, linked to various cardiometabolic diseases. This study aimed to analyze the association between dyslipidemia and myosteatosis using abdominal computed tomography (CT) in a large population.

Methods

This study included 11,823 patients not taking lipid-lowering medications with abdominal CT taken between 2012 and 2013. Total abdominal muscle area (TAMA), measured at the L3 level, was segmented into skeletal muscle area (SMA) and intramuscular adipose tissue. SMA was further classified into normal attenuation muscle area (NAMA: good quality muscle) and low attenuation muscle area (poor quality muscle). NAMA divided by TAMA (NAMA/TAMA) represents good quality muscle. Atherosclerotic dyslipidemia was defined as high-density lipoprotein cholesterol (HDL-C) less than 40 mg/dL in men and 50 mg/dL in women, low-density lipoprotein cholesterol (LDL-C) greater than 160 mg/dL, triglycerides (TG) greater than 150 mg/dL, small dense LDL-C (sdLDL-C) greater than 50.0 mg/dL, or apolipoprotein B/A1 (apoB/A1) greater than 0.08.

Results

The adjusted odds ratios (ORs) of dyslipidemia according to the HDL-C and sdLDL definitions were greater in both sexes in the lower quartiles (Q1~3) of NAMA/TAMA compared with Q4. As per other definitions, the ORs were significantly increased in only women for LDL-C and only men for TG and ApoB/A1. In men, all lipid parameters were significantly associated with NAMA/TAMA, while TG and ApoB/A1 did not show significant association in women.

Conclusion

Myosteatosis measured in abdominal CT was significantly associated with a higher risk of dyslipidemia. Myosteatosis may be an important risk factor for dyslipidemia and ensuing cardiometabolic diseases.

Myosteatosis predicts postoperative complications and long-term survival in robotic gastrectomy for gastric cancer: A propensity score analysis

BACKGROUND

Robotic gastrectomy is increasingly utilized for gastric cancer, but high morbidity remains a concern. Myosteatosis or low skeletal muscle density reflecting fatty infiltration, associates with complications after other cancer surgeries but has not been evaluated for robotic gastrectomy.

METHODS

This retrospective study analysed 381 patients undergoing robotic gastrectomy for gastric cancer from September 2019 to October 2022. Myosteatosis was quantified on preoperative computed tomography (CT) images at lumbar 3 (L3). Propensity score matching addressed potential confounding between myosteatosis and non-myosteatosis groups. Outcomes were postoperative complications, 30 days mortality, 30 days readmissions and survival.

RESULTS

Myosteatosis was present in 33.6% of patients. Myosteatosis associated with increased overall (47.7% vs. 26.5%, p < 0.001) and severe complications (12.4% vs. 4.9%, p < 0.001). After matching, myosteatosis remained associated with increased overall complications, major complications, intensive care unit (ICU) transfer and readmission (all p < 0.05). Myosteatosis independently predicted overall [odds ratio (OR) = 2.86, 95% confidence interval (CI): 1.57-5.20, p = 0.001] and severe complications (OR = 4.81, 95% CI: 1.51-15.27, p = 0.008). Myosteatosis also associated with reduced overall (85.0% vs. 93.2%, p = 0.015) and disease-free survival (80.3% vs. 88.4%, p=0.029). On multivariate analysis, myosteatosis independently predicted poorer survival [hazard ratio (HR) = 2.83, 95% CI: 1.32-6.08, p=0.012] and disease-free survival (HR = 1.83, 95% CI: 1.01-3.30, p=0.032).

CONCLUSION

Preoperative CT-defined myosteatosis independently predicts increased postoperative complications and reduced long-term survival after robotic gastrectomy for gastric cancer. Assessing myosteatosis on staging CT could optimize preoperative risk stratification.

Association between metabolic dysfunction-associated steatotic liver disease and myosteatosis measured by computed tomography

BACKGROUND

In 2023, the concept of metabolic dysfunction-associated steatotic liver disease (MASLD) was introduced as an alternative to non-alcoholic fatty liver disease (NAFLD). We aimed to assess the quantity and quality of skeletal muscle using each of these diagnostic classifications.

METHODS

This cross-sectional study included 18 154 participants (11 551 [63.6%] men and 6603 [36.4%] women, mean age 53.0 ± 8.8). The participants were classified into four categories: neither steatotic liver disease (SLD), NAFLD only, MASLD only or both SLDs. An appendicular skeletal muscle mass adjusted for body mass index of <0.789 for men and <0.512 for women was defined as sarcopenia. The total abdominal muscle area (TAMA) at the L3 vertebral level was segmented into normal-attenuation muscle area (NAMA), low-attenuation muscle area and intermuscular/intramuscular adipose tissue. Myosteatosis was defined by a T-score < -1.0 of the NAMA/TAMA index, which was calculated by dividing the NAMA by the TAMA and multiplying by 100.

RESULTS

Using subjects with neither SLD as a reference, the multivariable-adjusted odds ratios (ORs) for sarcopenia were significantly increased in those with MASLD, with adjusted ORs (95% confidence interval [CI]) of 2.62 (1.94-3.54) in the MASLD-only group and 2.33 (1.92-2.82) in the both SLDs group, while the association was insignificant in those with NAFLD only (adjusted OR [95% CI]: 2.16 [0.67-6.94]). The OR for myosteatosis was also elevated in the MASLD groups, with an OR (95% CI) of 1.75 (1.52-2.02) in subjects with MASLD only and 1.70 (1.57-1.84) in those with both SLDs, while it was slightly decreased in subjects with NAFLD only (0.52 [0.29-0.95]).

CONCLUSIONS

Employing the MASLD concept rather than that of the NAFLD proved to be more effective in distinguishing individuals with reduced muscle mass and compromised muscle quality.

CT-based muscle and adipose measurements predict prognosis in patients with digestive system malignancy

The role of skeletal muscle and adipose tissue in the progression of cancer has been gradually discussed, but it needs further exploration. The objective of this study was to provide an in-depth analysis of skeletal muscle and fat in digestive malignancies and to construct novel predictors for clinical management. This is a retrospective study that includes data from Cancer Center, the First Hospital of Jilin University. Basic characteristic information was analyzed by T tests. Correlation matrices were drawn to explore the relationship between CT-related indicators and other indicators. Cox risk regression analyses were performed to analyze the association between the overall survivals (OS) and various types of indicators. A new indicator body composition score (BCS) was then created and a time-dependent receiver operating characteristic curve was plotted to analyze the efficacy of the BCS. Finally, a nomogram was produced to develop a scored-CT system based on BCS and other indicators. C-index and calibration curve analyses were performed to validate the predictive accuracy of the scored-CT system. A total of 575 participants were enrolled in the study. Cox risk regression model revealed that VFD, L3 SMI and VFA/SFA were associated with prognosis of cancer patients. After adjustment, BCS index based on CT was significantly associated with prognosis, both in all study population and in subgroup analysis according to tumor types (all study population: HR 2.036, P < 0.001; colorectal cancer: HR 2.693, P < 0.001; hepatocellular carcinoma: HR 4.863, P < 0.001; esophageal cancer: HR 4.431, P = 0.008; pancreatic cancer: HR 1.905, P = 0.016; biliary system malignancies: HR 23.829, P = 0.035). The scored-CT system was constructed according to tumor type, stage, KPS, PG-SGA and BCS index, and it was of great predictive validity. This study identified VFD, L3 SMI and VFA/SFA associated with digestive malignancies outcomes. BCS was created and the scored-CT system was established to predict the OS of cancer patients.

Prevalence and impact on the outcome of myosteatosis in patients with cirrhosis: a systematic review and meta-analysis

BACKGROUND

Myosteatosis in cirrhotic patients has been evaluated in limited studies with conflicting results and no systematic review or meta-analysis have been performed in this setting.

METHODS

We searched for all articles published until June 2023 to evaluate the prevalence of myosteatosis in cirrhosis and chronic liver disease.

RESULTS

Seventeen studies focused on cirrhosis and five studies in patients with chronic liver disease were included: the overall pooled prevalence of myosteatosis was 46% [95% Confidence Interval (CI) 36-57%] and 33% (95% CI 15-59%), respectively (p = 0.35). Among the studies with cirrhosis, the prevalence of myosteatosis was higher in those using the body mass index-based definition of myosteatosis (56%), than gender-based (36%) or other criteria (21%) (p < 0.01); was higher in women than in men (61% vs 45%), in Child-Pugh class C than A or B (57% vs 49% vs 50%), in non-alcoholic fatty liver disease (NAFLD)- than viral-associated cirrhosis (57% vs 43%), but these differences were not statistically significant (p > 0.05). Cirrhotic patients with myosteatosis, compared to those without myosteatosis, had more frequently a previous history of hepatic encephalopathy (32% vs 15%, p = 0.04), less frequently a previous history of variceal bleeding (46% vs 65%, p < 0.01), were more likely to suffer from diabetes mellitus (27% vs 18%, p < 0.01), while they had higher mortality rates (40% vs 14%, p = 0.02).

CONCLUSION

Myosteatosis is highly prevalent in patients with cirrhosis, particularly in those with NAFLD-associated cirrhosis. Myosteatosis is associated with hepatic encephalopathy, while it seems to have a negative impact on the outcome.

Myosteatosis is associated with poor survival after kidney transplantation: a large retrospective cohort validation

PURPOSE

We aim to establish diagnostic thresholds of sarcopenia and myosteatosis based on CT measurements, and to validate their prognostic value in a large cohort of kidney transplant recipients.

METHODS

Local healthy population with abdominal CT between 2010 and 2022, and patients underwent kidney transplantation between 2015 and 2019 at our center were retrospectively included. The skeletal muscle index and muscle attenuation of abdominal muscles were calculated based on CT image at the middle of the third lumbar vertebra. Primary endpoints included all-cause mortality and death censored allograft survival.

RESULTS

Age- and sex-specific thresholds for sarcopenia and myosteatosis were established based on 1598 healthy local population. The final patient cohort consisted of 992 kidney transplant recipients (median age 34 years, interquartile range 28-44 years; 694 males), including 33 (3.3%) with sarcopenia and 95 (9.5%) with myosteatosis. Multivariate analysis revealed myosteatosis (adjusted hazard ratio = 3.08, p = 0.022) was an independent baseline risk factor of mortality after adjusting for age, the history of cancer, and the history of cardiovascular event. Multivariate analysis found preemptive transplantation (adjusted hazard ratio = 0.36, p = 0.037) was an independent protective factor of allograft loss. No difference was found in the prognosis between kidney transplant recipients with and without sarcopenia.

CONCLUSION

Myosteatosis was an independent risk factor of mortality after kidney transplantation, but sarcopenia was not. Neither sarcopenia nor myosteatosis was associated with graft loss.

Making the invisible visible: imaging techniques for assessing muscle mass and muscle quality in chronic kidney disease

Muscle wasting and low muscle mass are prominent features of protein energy wasting (PEW), sarcopenia and sarcopenic obesity in patients with chronic kidney disease (CKD). In addition, muscle wasting is associated with low muscle strength, impaired muscle function and adverse clinical outcomes such as low quality of life, hospitalizations and increased mortality. While assessment of muscle mass is well justified, the assessment of skeletal muscle should go beyond quantity. Imaging techniques provide the means for non-invasive, comprehensive, in-depth assessment of the quality of the muscle such as the infiltration of ectopic fat. These techniques include computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Dual energy X-ray absorptiometry is also an imaging technique, but one that only provides quantitative and not qualitative data on muscle. The main advantage of imaging techniques compared with other methods such as bioelectrical impedance analysis and anthropometry is that they offer higher precision and accuracy. On the other hand, the higher cost for acquiring and maintaining the imaging equipment, especially CT and MRI, makes these less-used options and available mostly for research purposes. In the field of CKD and end-stage kidney disease (ESKD), imaging techniques are gaining attention for evaluating muscle quantity and more recently muscle fat infiltration. This review describes the potential of these techniques in CKD and ESKD settings for muscle assessment beyond that of muscle quantity.

Prognostic value of deep learning-derived body composition in advanced pancreatic cancer-a retrospective multicenter study

BACKGROUND

Despite the prognostic relevance of cachexia in pancreatic cancer, individual body composition has not been routinely integrated into treatment planning. In this multicenter study, we investigated the prognostic value of sarcopenia and myosteatosis automatically extracted from routine computed tomography (CT) scans of patients with advanced pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

We retrospectively analyzed clinical imaging data of 601 patients from three German cancer centers. We applied a deep learning approach to assess sarcopenia by the abdominal muscle-to-bone ratio (MBR) and myosteatosis by the ratio of abdominal inter- and intramuscular fat to muscle volume. In the pooled cohort, univariable and multivariable analyses were carried out to analyze the association between body composition markers and overall survival (OS). We analyzed the relationship between body composition markers and laboratory values during the first year of therapy in a subgroup using linear regression analysis adjusted for age, sex, and American Joint Committee on Cancer (AJCC) stage.

RESULTS

Deep learning-derived MBR [hazard ratio (HR) 0.60, 95% confidence interval (CI) 0.47-0.77, P < 0.005] and myosteatosis (HR 3.73, 95% CI 1.66-8.39, P < 0.005) were significantly associated with OS in univariable analysis. In multivariable analysis, MBR (P = 0.019) and myosteatosis (P = 0.02) were associated with OS independent of age, sex, and AJCC stage. In a subgroup, MBR and myosteatosis were associated with albumin and C-reactive protein levels after initiation of therapy. Additionally, MBR was also associated with hemoglobin and total protein levels.

CONCLUSIONS

Our work demonstrates that deep learning can be applied across cancer centers to automatically assess sarcopenia and myosteatosis from routine CT scans. We highlight the prognostic role of our proposed markers and show a strong relationship with protein levels, inflammation, and anemia. In clinical practice, automated body composition analysis holds the potential to further personalize cancer treatment.

Association Between Insulin Resistance and Myosteatosis Measured by Abdominal Computed Tomography

CONTEXT

Ectopic fat deposition in skeletal muscle, termed myosteatosis, is a key factor in developing insulin resistance.

OBJECTIVE

This work aimed to evaluate the association between insulin resistance and myosteatosis in a large Asian population.

METHODS

A total of 18 251 participants who had abdominal computed tomography were included in this cross-sectional study. Patients were categorized into 4 groups according to quartiles of Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). The total abdominal muscle area (TAMA) at the L3 vertebral level was segmented into normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA), and intermuscular adipose tissue (IMAT). The absolute values of TAMA, NAMA, LAMA, and IMAT and the ratios of NAMA/BMI, LAMA/BMI, and NAMA/TAMA were used as myosteatosis indices.

RESULTS

The absolute values of TAMA, NAMA, LAMA, and IMAT appeared to increase with higher HOMA-IR levels, and LAMA/BMI showed a similar upward trend. Meanwhile, the NAMA/BMI and NAMA/TAMA index showed downward trends. As HOMA-IR levels increased, the odds ratios (ORs) of the highest quartile of NAMA/BMI and NAMA/TAMA index decreased and that of LAMA/BMI increased. Compared with the lowest HOMA-IR group, the adjusted ORs (95% CI) in the highest HOMA-IR group for the lowest NAMA/TAMA quartile were 0.414 (0.364-0.471) in men and 0.464 (0.384-0.562) in women. HOMA-IR showed a negative correlation with NAMA/BMI (r = -0.233 for men and r = -0.265 for women), and NAMA/TAMA index (r = -0.211 for men and r = -0.214 for women), and a positive correlation with LAMA/BMI (r = 0.160 for men and r = 0.119 for women); P was less than .001 for all.

CONCLUSION

In this study, a higher HOMA-IR level was significantly associated with a high risk of myosteatosis.

Cigarette smoking and disproportionate changes of thoracic skeletal muscles in low-dose chest computed tomography

Association between smoking intensity and the quantity and quality of thoracic skeletal muscles (TSMs) remains unexplored. Skeletal muscle index (SMI; skeletal muscle area/height2) and percentage of normal attenuation muscle area (NAMA%) were measured to represent the quantity and quality of the skeletal muscles, respectively, and quantification was performed in pectoralis muscle at aortic arch (AA-PM), TSM at carina (C-TSM), erector spinae muscle at T12 (T12-ESM), and skeletal muscle at L1 (L1-SM). Among the 258 men (median age, 62 years [IQR: 58-69]), 183 were current smokers (median smoking intensity, 40 pack-years [IQR: 30-46]). SMI and NAMA% of AA-PM significantly decreased with pack-year (β =  - 0.028 and - 0.076; P < 0.001 and P = 0.021, respectively). Smoking intensity was inversely associated with NAMA% of C-TSM (β =  - 0.063; P = 0.001), whereas smoking intensity showed a borderline association with SMI of C-TSM (β =  - 0.023; P = 0.057). Smoking intensity was associated with the change in NAMA% of L1-SM (β =  - 0.040; P = 0.027), but was not associated with SMI of L1-SM (P > 0.05). Neither NAMA% nor SMI of T12-ESM was affected by smoking intensity (P > 0.05). In conclusion, smoking intensity was associated with the change of TSMs. Its association varied according to the location of TSMs, with the most associated parts being the upper (AA-PM) and middle TSMs (C-TSM).

Association of Visceral Fat Obesity, Sarcopenia, and Myosteatosis with Non-Alcoholic Fatty Liver Disease without Obesity

BACKGROUND/AIMS

To investigate whether non-alcoholic fatty liver disease (NAFLD) in individuals without generalized obesity is associated with visceral fat obesity (VFO), sarcopenia, and/or myosteatosis.

METHODS

This cross-sectional analysis included 14,400 individuals (7,470 men) who underwent abdominal computed tomography scans during routine health examinations. The total abdominal muscle area (TAMA) and skeletal muscle area (SMA) at the 3rd lumbar vertebral level were measured. The SMA was divided into the normal attenuation muscle area (NAMA) and low attenuation muscle area, and the NAMA/TAMA index was calculated. VFO was defined by visceral to subcutaneous fat ratio, sarcopenia by body mass index-adjusted SMA, and myosteatosis by the NAMA/TAMA index. NAFLD was diagnosed with ultrasonography.

RESULTS

Of the 14,400 individuals, 4,748 (33.0%) had NAFLD, and the prevalence of NAFLD among non-obese individuals was 21.4%. In regression analysis, both sarcopenia (men: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.19-1.67, P<0.001; women: OR=1.59, 95% CI 1.40-1.90, P<0.001) and myosteatosis (men: OR=1.24, 95% CI 1.02-1.50, P=0,028; women: OR=1.23, 95% CI 1.04-1.46, P=0.017) were significantly associated with non-obese NAFLD after considering for VFO and other various risk factors, whereas VFO (men: OR=3.97, 95% CI 3.43-4.59 [adjusted for sarcopenia], OR 3.98, 95% CI 3.44-4.60 [adjusted for myosteatosis]; women: OR=5.42, 95% CI 4.53-6.42 [adjusted for sarcopenia], OR=5.33, 95% CI 4.51-6.31 [adjusted for myosteatosis]; all P<0.001) was strongly associated with non-obese NAFLD after adjustment with various known risk factors.

CONCLUSION

In addition to VFO, sarcopenia and/or myosteatosis were significantly associated with non-obese NAFLD.

Prognostic Value of Artificial Intelligence-Driven, Computed Tomography-Based, Volumetric Assessment of the Volume and Density of Muscle in Patients With Colon Cancer

OBJECTIVE

The prognostic value of the volume and density of skeletal muscles in the abdominal waist of patients with colon cancer remains unclear. This study aimed to investigate the association between the automated computed tomography (CT)-based volume and density of the muscle in the abdominal waist and survival outcomes in patients with colon cancer.

MATERIALS AND METHODS

We retrospectively evaluated 474 patients with colon cancer who underwent surgery with curative intent between January 2010 and October 2017. Volumetric skeletal muscle index and muscular density were measured at the abdominal waist using artificial intelligence (AI)-based volumetric segmentation of body composition on preoperative pre-contrast CT images. Patients were grouped based on their skeletal muscle index (sarcopenia vs. not) and muscular density (myosteatosis vs. not) values and combinations (normal, sarcopenia alone, myosteatosis alone, and combined sarcopenia and myosteatosis). Postsurgical disease-free survival (DFS) and overall survival (OS) were analyzed using univariable and multivariable analyses, including multivariable Cox proportional hazard regression.

RESULTS

Univariable analysis showed that DFS and OS were significantly worse for the sarcopenia group than for the non-sarcopenia group (P = 0.044 and P = 0.003, respectively, by log-rank test) and for the myosteatosis group than for the non-myosteatosis group (P < 0.001 by log-rank test for all). In the multivariable analysis, the myosteatotic muscle type was associated with worse DFS (adjusted hazard ratio [aHR], 1.89 [95% confidence interval, 1.25-2.86]; P = 0.003) and OS (aHR, 1.90 [95% confidence interval, 1.84-3.04]; P = 0.008) than the normal muscle type. The combined muscle type showed worse OS than the normal muscle type (aHR, 1.95 [95% confidence interval, 1.08-3.54]; P = 0.027).

CONCLUSION

Preoperative volumetric sarcopenia and myosteatosis, automatically assessed from pre-contrast CT scans using AI-based software, adversely affect survival outcomes in patients with colon cancer.

Association between sarcopenic obesity and poor muscle quality based on muscle quality map and abdominal computed tomography

OBJECTIVE

This study evaluated whether sarcopenic obesity is closely associated with muscle quality using abdominal computed tomography.

METHODS

This cross-sectional study included 13,612 participants who underwent abdominal computed tomography. The cross-sectional area of the skeletal muscle was measured at the L3 level (total abdominal muscle area [TAMA]) and segmented into normal attenuation muscle area (NAMA, +30 to +150 Hounsfield units), low attenuation muscle area (-29 to +29 Hounsfield units), and intramuscular adipose tissue (-190 to -30 Hounsfield units). The NAMA/TAMA index was calculated by dividing NAMA by TAMA and multiplying by 100, and the lowest quartile of NAMA/TAMA index was defined as myosteatosis (<73.56 in men and <66.97 in women). Sarcopenia was defined using BMI-adjusted appendicular skeletal muscle mass.

RESULTS

The prevalence of myosteatosis was found to be significantly higher in participants with sarcopenic obesity (17.9% vs. 54.2%, p < 0.001) than the control group without sarcopenia or obesity. Compared with the control group, the odds ratio (95% CI) for having myosteatosis was 3.70 (2.87-4.76) for participants with sarcopenic obesity after adjusting for age, sex, smoking, drinking, exercise, hypertension, diabetes, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein.

CONCLUSIONS

Sarcopenic obesity is significantly associated with myosteatosis, which is representative of poor muscle quality.

Muscle fat infiltration in chronic kidney disease: a marker related to muscle quality, muscle strength and sarcopenia

Muscle fat infiltration (MFI) also known as myosteatosis refers to any deposit of lipids found in the skeletal muscle. MFI is preferably assessed by image-based methods like computed tomography (CT), magnetic resonance image (MRI) and ultrasound, normally from muscle groups located in the legs, arms and in the trunk. MFI is understood as a marker of muscle quality, where a muscle with higher fat deposition has lower contraction power and capacity to produce force per unit of muscle mass. This concept supports the hypothesis that a decrease in muscle strength is not always explained by a decrease in muscle mass, but also by other factors, including lipid deposition in the muscle. In the general population, MFI is associated with older age, physical inactivity and with insulin resistance and inflammation. In chronic kidney disease (CKD), MFI has been associated with a decrease in muscle strength and impaired muscle quality as well as with metabolic abnormalities, cardiovascular disease and increased mortality. Interventions aimed at reducing MFI in CKD are incipient, but it seems that guided exercise can ameliorate muscle quality in patients on hemodialysis. The aim of this narrative review about MFI in CKD is to draw attention to a still not often addressed complication in CKD. We conclude that more studies are warranted to investigate mechanisms and factors promoting MFI in CKD. Thus, clinical trials aimed at understanding the type, frequency and intensity of exercise that can diminish MFI and improve the clinical condition of the patients are needed.

Associations of Trunk Muscle Mass and Muscle Quality Indicators with Self-Reported Dysphagia in Older Inpatients

Recent studies have correlated dysphagia with ultrasound-measured quadriceps muscle mass and quality. Computed tomography (CT) is more precise than ultrasound for estimating muscle mass and quality. We aimed to investigate the possible associations of chest CT-determined trunk muscle mass and quality with dysphagia. A cross-sectional study. Older inpatients in a geriatric department of a university hospital. Self-reported dysphagia was determined by the Dysphagia Handicap Index. Unenhanced chest CT images were segmented to calculate skeletal muscle area (SMA) and intermuscular adipose tissue (IMAT). Skeletal muscle index (SMI) was calculated via SMA/ height squared. The percentage of IMAT (IMAT%) was calculated by IMAT% = IMAT/ (SMA + IMAT) × 100%. Mimics software was applied to calculate the mean skeletal muscle radio density (SMD).The semiquantitative food frequency method, the Barthel Index (BI), and the Mini Nutritional Assessment Short-Form (MNA-SF) were used to evaluate energy intake, activities of daily living, and nutrition status, respectively. Among the 212 participants (mean age: 84 years), 89 (42%) had self-reported dysphagia. After adjustment for age, nutrition status, energy intake, and other confounders, the SMI (adjusted OR 0.91, 95% CI 0.86, 0.96) was negatively associated with dysphagia, whereas the IMAT (adjusted OR 1.08, 95% CI 1.01, 1.16) and the IMAT% (adjusted OR 1.10, 95% CI 1.04,1.17) were positively associated with dysphagia. However, the SMD (adjusted OR 0.99, 95% CI 0.94, 1.05) was not significantly associated with dysphagia. The subgroup analyses indicated that only the SMI (adjusted OR 0.92, 95% CI 0.86, 0.97) and the IMAT% (adjusted OR 1.08, 95% CI 1.01, 1.17) were significantly associated with dysphagia in men. None of these indicators was significantly associated with dysphagia in women. Trunk muscle mass and quality (estimated by chest CT-derived SMI and IMAT%, respectively) were significantly associated with self-reported dysphagia in older inpatients, especially in men. IMAT% might be a more sensitive muscle quality indicator than IMAT (or SMD). These results merit further investigation in prospective studies.

Correlation between fat infiltration of paraspinal muscle and L4 degenerative lumbar spondylolisthesis in asymptomatic adults

OBJECTIVE

To explore the relationship between different indicators of the degree of fat infiltration and L4 Degenerative lumbar spondylolisthesis (DLS).

METHODS

128 patients received annual health check-up underwent lumbar lateral Digital Radiography (DR) and abdominal Computed tomography (CT) imaging were enrolled. The DLS group included 60 patients diagnosed with DLS, and the control group included 68 patients without DLS. The data collected included vertebral density of L4-L5, fat infiltration ratio (FIR) of paravertebral muscle (PM) and psoas major muscle (PMM), skeletal muscle density of PM and PMM, low attenuation muscle ratio (LTR) of PM and PMM, paraspinal muscle density (PMD), psoas major muscle density (PMMD), low attenuation muscle density (LMD) of PM and PMM, facet joint angle (FJA), facet joint degeneration (FJD), etc. RESULTS: PM FIR and PM LTR were weakly positively correlated with the degree of L4 DLS, and there was a weak negative correlation between PMD and the degree of L4 DLS in asymptomatic adults (P < 0.05). Logistic regression analysis showed that PM FIR was an independent related factor of L4 DLS (Q3 vs. Q1, OR = 3.746, 95% CI: 1.076-13.048, p = 0.038). ROC curve analysis showed that the PM FIR has a high predictive value for L4 DLS in asymptomatic adults.

CONCLUSION

The indicator of PM FIR was an independent related factor of L4 DLS in asymptomatic adults. It has a high predictive value for L4 DLS and can be applied as a potential target for clinical treatment of L4 DLS in asymptomatic adults.

Association between hypertension and myosteatosis evaluated by abdominal computed tomography

Few studies have examined the relationship between myosteatosis and hypertension, and no studies have enrolled an Asian population. Existing studies also found discordant results, possibly due to the use of conventional myosteatosis indices that are not sufficiently reliable and representative. Therefore, we investigated the association between myosteatosis and hypertension in Asian individuals using novel, objective computed tomography (CT) markers. The total abdominal muscle area (TAMA) was determined from abdominal CT scans taken at the L3 level. Based on the mean CT attenuation, the TAMA was divided into intramuscular adipose tissue and skeletal muscle area (SMA), which was further segmented into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). Among SMA/body mass index (BMI), NAMA/BMI, LAMA/BMI, and the NAMA/TAMA index, NAMA/BMI was chosen through receiver operating characteristic curves as the best predictive marker for hypertension. The hypertension risk for each quartile of NAMA/BMI was calculated by logistic regression analysis. Among the 19,766 participants, 40.3% of men and 23.8% of women had hypertension. People with hypertension showed unhealthier myosteatosis profiles than normotensive controls. Similarly, a lower NAMA/BMI was significantly associated with a greater hypertension risk. The lowest quartile group of NAMA/BMI exhibited 2.3- and 2.6-fold higher risks of hypertension than the highest quartile in men and women, respectively. In conclusion, advanced myosteatosis assessed by abdominal CT was significantly correlated with a higher risk of hypertension. Improving myosteatosis may be a new approach for preventing cardiovascular diseases, including hypertension. Advanced myosteatosis measured by abdominal CT taken at the L3 level was significantly correlated with a higher risk of hypertension even after adjusting for health behaviors, intake of lipid-lowering drugs, plasma lipid levels, and other ectopic fat distribution.

Association of Myosteatosis with Nonalcoholic Fatty Liver Disease, Severity, and Liver Fibrosis Using Visual Muscular Quality Map in Computed Tomography

BACKGROUND

The association of myosteatosis measured using visual muscular quality map in computed tomography (CT) with nonalcoholic fatty liver disease (NAFLD), its severity, and fibrosis was analyzed in a large population.

METHODS

Subjects (n=13,452) with abdominal CT between 2012 and 2013 were measured total abdominal muscle area (TAMA) at L3 level. TAMA was segmented into intramuscular adipose tissue and skeletal muscle area (SMA), which was further classified into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). The following variables were adopted as indicators of myosteatosis: SMA/body mass index (BMI), NAMA/BMI, NAMA/TAMA, and LAMA/BMI. NAFLD and its severity were assessed by ultrasonography, and liver fibrosis was measured by calculating the NAFLD fibrosis score (NFS) and fibrosis-4 index (FIB-4) scores.

RESULTS

According to multiple logistic regression analyses, as quartiles of SMA/BMI, NAMA/BMI, and NAMA/TAMA increased, the odds ratios (ORs) for NAFLD decreased in each sex (P for trend <0.001 for all). The ORs of moderate/severe NAFLD were significantly higher in the Q1 group than in the Q4 group for SMA/BMI, NAMA/BMI, and NAMA/TAMA in men. The ORs of intermediate/high liver fibrosis scores assessed by NFS and FIB-4 scores increased linearly with decreasing quartiles for SMA/BMI, NAMA/BMI, and NAMA/TAMA in each sex (P for trend <0.001 for all). Conversely, the risk for NAFLD and fibrosis were positively associated with LAMA/BMI quartiles in each sex (P for trend <0.001 for all).

CONCLUSION

A higher proportion of good quality muscle was associated with lower risks of NAFLD and fibrosis.

Effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced GIST

BACKGROUND

Currently, the effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced gastrointestinal stromal tumors (LA-GIST) remains unclear. This study aims to investigate the relationship between changes in skeletal muscle and postoperative complications, survival and tumor response in patients with LA-GIST during neoadjuvant therapy with imatinib.

METHODS

We retrospectively analyzed pre- and post-treatment computed tomography images of 57 GIST patients who underwent radical surgery after neoadjuvant therapy with imatinib from January 2013 to March 2019. Skeletal muscle index (SMI) was measured at the L3 vertebral level in all patients. A cut-off value (SMI < 52.3 cm²/m² and < 38.6 cm²/m² for men and women, respectively) published in a previous study was used to define sarcopenia. Based on gender, we defined ΔSMI (%)/250 days above 9.69% for men and ΔSMI (%)/250 days above 7.63% for women as significant muscle loss (SML). Factors associated with postoperative complications and tumor response were analyzed using logistic regression, and predictors affecting patient prognosis were analyzed using Cox regression.

RESULTS

Of the 57 patients, sarcopenia was present before and after neoadjuvant therapy in 20 (35.09%) and 28 (49.12%) patients, respectively. It was not associated with immediate or long-term clinical outcomes. However, patients with SML during neoadjuvant therapy had a higher incidence of postoperative complications (60.00% vs. 25.00%, p = 0.008), worse pathological regression (44.00% vs. 75.00%, p = 0.017) and worse 3-year survival (Male, 68.75% vs. 95.45%, p = 0.027; Female, 66.67% vs. 100.00%, p = 0.046) than patients without SML.

CONCLUSION

The development of SML during neoadjuvant therapy in LA-GIST patients, rather than pre- and post-treatment sarcopenia, is a major prognostic factor for the long-term prognosis and is also associated with recent postoperative complication rates and pathological regression.

Association between type 2 diabetes and skeletal muscle quality assessed by abdominal computed tomography scan

AIM

To examine the association between type 2 diabetes and the amount and quality of trunk muscle as assessed by computed tomography (CT) scan.

MATERIALS AND METHODS

A total of 20,986 subjects (13,007 men and 7979 women) who underwent abdominal CT scan as part of a routine health check-up were included. The total abdominal muscle area (TAMA) measured at the third lumbar vertebrae was classified into skeletal muscle area (SMA), and intermuscular adipose tissue area. SMA was divided into good quality muscles (normal attenuation muscle area [NAMA]) and poor quality muscles (low attenuation muscle area). NAMA/TAMA index was calculated.

RESULTS

Subjects with type 2 diabetes had higher values of TAMA and SMA but significantly lower values of NAMA and NAMA/TAMA index. Compared with those in the lowest quartile of NAMA/TAMA index, subjects in the highest quartile had metabolically favourable laboratory findings, a lower prevalence of type 2 diabetes (Q1 vs. Q4: 19.3% vs. 9.5% in men, 12.3% vs. 3.0% in women) and inverse association with type 2 diabetes (odds ratio for Q2, Q3, and Q4: 0.87, 0.78, and 0.75 in men; 0.82, 0.70, and 0.68 in women) after multivariable adjustment.

CONCLUSIONS

The amount of good quality muscle on CT scan was associated with a lower prevalence of type 2 diabetes.

Chest computed tomography-derived muscle mass and quality indicators, in-hospital outcomes, and costs in older inpatients

BACKGROUND

Muscle mass and muscle quality assessed by computed tomography (CT) have been associated with poor prognosis in oncology and surgery patients, but the relevant evidence was limited in older patients. We hypothesized that muscle mass and muscle quality indicators derived from opportunistic chest CT images at the 12th thorax vertebra level (T12) could predict in-hospital death, length of hospital stay (hospital LOS), and hospital costs among older patients in acute care wards.

METHODS

We conducted a prospective cohort study. Older patients admitted to the acute geriatric wards of a teaching hospital were continuously recruited. Chest CT images were analysed using SliceOmatic software. The skeletal muscle area, skeletal muscle radiodensity, and intermuscular adipose tissue (IMAT) at the T12 level were measured. Skeletal muscle index (SMI) was calculated using skeletal muscle area divided by body height squared.

RESULTS

We included 1135 older patients with a median age of 80 years (interquartile range, 73 to 85 years), 498 (44%) were women, 148 (13%) patients died during hospitalization. The SMI and SMD were negatively correlated to age (ρ = -0.11, P < 0.001, ρ = -0.30, P < 0.001, respectively), whereas the IMAT was positively correlated to age (ρ = 0.27, P < 0.001). Compared with survivors, dead patients had significantly lower SMI in men (P < 0.001) but not in women (P = 0.760). After adjusting for sex and other potential confounders, the SMI [increased per 1 cm² /m² , odds ratio (OR) 0.96, 95% confidence interval (CI) 0.93 to 0.99] and SMD (increased per 1 Hounsfield unit, OR 0.93, 95% CI 0.90 to 0.96) were negatively and independently associated with in-hospital death, whereas the IMAT (increased per 1 cm² , OR 1.09, 95% CI 1.05 to 1.14) was independently and positively associated with in-hospital death. None of the SMI, SMD, or IMAT was significantly related to long hospital LOS or increased hospital costs.

CONCLUSIONS

Chest CT-derived muscle mass indicator (T12 SMI) and muscle quality indicators (T12 SMD and T12 IMAT) may serve as prognostic factors for predicting in-hospital death among older inpatients. Opportunistic chest CT images might be an overlooked resource for measuring muscle mass and muscle quality and for predicting short-term prognosis in older inpatients.

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.

A reliable and robust method for the upper thigh muscle quantification on computed tomography: toward a quantitative biomarker for sarcopenia

Background

We aimed to evaluate the feasibility of the upper thigh level as a landmark to measure muscle area for sarcopenia assessment on computed tomography (CT).

Methods

In the 116 healthy subjects who performed CT scans covering from mid-abdomen to feet, the skeletal muscle area in the upper thigh level at the inferior tip of ischial tuberosity (SMA_UT), the mid-thigh level (SMA_MT), and L3 inferior endplate level (SMA_L3) were measured by two independent readers. Pearson correlation coefficients between SMA_UT, SMA_MT, and SMA_L3 were calculated. Inter-reader agreement between the two readers were evaluated using intraclass correlation coefficient (ICC) and Bland-Altman plots with 95% limit of agreement (LOA).

Results

In readers 1 and 2, very high positive correlations were observed between SMA_UT and SMA_MT (r = 0.91 and 0.92, respectively) and between SMA_UT and SMA_L3 (r = 0.90 and 0.91, respectively), while high positive correlation were observed between SMA_MT and SMA_L3 (r = 0.87 and 0.87, respectively). Based on ICC values, the inter-reader agreement was the best in the SMA_UT (0.999), followed by the SMA_L3 (0.990) and SMA_MT (0.956). The 95% LOAs in the Bland-Altman plots indicated that the inter-reader agreement of the SMA_UT (− 0.462 to 1.513) was the best, followed by the SMA_L3 (− 9.949 to 7.636) and SMA_MT (− 12.105 to 14.605).

Conclusion

Muscle area measurement at the upper thigh level correlates well with those with the mid-thigh and L3 inferior endpoint level and shows the highest inter-reader agreement. Thus, the upper thigh level might be an excellent landmark enabling SMA_UT as a reliable and robust biomarker for muscle area measurement for sarcopenia assessment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05032-2.

Malnutrition in Relation to Muscle Mass, Muscle Quality, and Muscle Strength in Hospitalized Older Adults

OBJECTIVES

Muscle quality is an essential muscle metric, which can be assessed by measuring intermuscular adipose tissue (IMAT) and skeletal muscle radiodensity (SMD) via computed tomography (CT) images. We aimed to explore the associations of Global Leadership Initiative on Malnutrition (GLIM)-defined malnutrition with muscle mass, muscle quality, and muscle strength in hospitalized older adults.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

Hospitalized older patients.

METHODS

Malnutrition was defined by the GLIM criteria after screening by the Mini Nutrition Assessment-Short Form (MNA-SF). Chest CT images were used to segment skeletal muscle area (SMA) and IMAT, and to measure SMD. Skeletal muscle index (SMI) was calculated by SMA (cm²)/body height squared (m²). Handgrip strength (HGS) was measured using a digital dynameter. Univariate and multivariate logistic regression models were performed to calculate odds ratios (ORs) and 95% CIs.

RESULTS

We included 1135 patients. The MNA-SF score is positively associated with SMI, SMD, and HGS, but negatively associated with IMAT. Compared to patients with normal nutrition, patients with malnutrition had significantly lower SMD and HGS in both men and women. Women with malnutrition had significantly higher IMAT than women with normal nutrition, whereas men with malnutrition had significantly lower SMI than men with normal nutrition. After adjustment for confounders, SMI (adjusted OR 0.95, 95% CI 0.93, 0.98), SMD (adjusted OR 0.94, 95% CI 0.93, 0.98), and HGS (adjusted OR 0.91, 95% CI 0.89, 0.94) were significantly and negatively associated with malnutrition. IMAT appeared to be positively associated with malnutrition, but the result was not statistically significant (adjusted OR 1.03, 95% CI 1.00, 1.07).

CONCLUSIONS AND IMPLICATIONS

Our study provides new evidence regarding the association between handgrip strength and malnutrition in older inpatients. Moreover, a small association of chest CT--derived muscle quality and mass with malnutrition is identified.

Computed Tomography-Derived Skeletal Muscle Radiodensity Is an Early, Sensitive Marker of Age-Related Musculoskeletal Changes in Healthy Adults

BACKGROUND

A decrease in computed tomography (CT)-derived skeletal muscle radiodensity (SMD) reflects age-related ectopic fat infiltration of muscle, compromising muscle function and metabolism. We investigated the age-related trajectory of SMD and its association with vertebral trabecular bone density in healthy adults.

METHODS

In a cohort of healthy adult kidney donors aged 19 to 69 years (n=583), skeletal muscle index (SMI, skeletal muscle area/height2), SMD, and visceral-to-subcutaneous fat (V/S) ratio were analyzed at the level of L3 from preoperative CT scans. Low bone mass was defined as an L1 trabecular Hounsfield unit (HU) <160 HU.

RESULTS

L3SMD showed constant decline from the second decade (annual change -0.38% and -0.43% in men and women), whereas the decline of L3SMI became evident only after the fourth decade of life (-0.37% and -0.18% in men and women). One HU decline in L3SMD was associated with elevated odds of low bone mass (adjusted odds ratio, 1.07; 95% confidence interval, 1.02 to 1.13; P=0.003), independent of L3SMI, age, sex, and V/S ratio, with better discriminatory ability compared to L3SMI (area under the receiver-operating characteristics curve 0.68 vs. 0.53, P<0.001). L3SMD improved the identification of low bone mass when added to age, sex, V/S ratio, and L3SMI (category-free net reclassification improvement 0.349, P<0.001; integrated discrimination improvement 0.015, P=0.0165).

CONCLUSION

L3SMD can be an early marker for age-related musculoskeletal changes showing linear decline throughout life from the second decade in healthy adults, with potential diagnostic value for individuals with low bone mass.

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.

Associations of ADL Disability With Trunk Muscle Mass and Muscle Quality Indicators Measured by Opportunistic Chest Computed Tomography Imaging Among Older Inpatients

Objectives: Sarcopenia is an important predictor of dependence in activities of daily living (ADL disability); however, the association between muscle quality and ADL disability has not been established. We aimed (1) to assess the feasibility of measuring trunk muscle mass and muscle quality by chest CT images; and (2) to explore the possible associations of ADL disability with these muscle mass and muscle quality indicators among older inpatients. Methods: We included older patients in an acute care ward. ADL disability was defined as the Barthel Index (BI) score ≤ 60 points. Unenhanced chest CT images at the 12^th thorax (T12) vertebral level were used to segment skeletal muscle area (SMA) and intermuscular adipose tissue (IMAT) and to measure the mean skeletal muscle radiodensity (SMD). Skeletal muscle index (SMI), the muscle mass indicator, was calculated by SMA (cm²)/body height squared (m²). The percentage of IMAT (IMAT%) was calculated using the equation: IMAT% = IMAT/(SMA+ IMAT) ×100%. Skeletal muscle radiodensity, IMAT, and IMAT% were the muscle quality indicators. Kendall's tau rank correlation coefficients (τ) were calculated to explore the correlations. Univariate and multivariate logistic regression models were performed to calculate odds ratios (OR) and 95% confidence interval (CI). Results: We included 212 participants. Skeletal muscle index and SMD were positively and significantly associated with the BI score (τ = 0.14 and 0.31, respectively, both P < 0.001); whereas IMAT and IMAT% were negatively and significantly associated with the BI score (τ = -0.21, P < 0.001; τ = -0.21, P < 0.012). After adjusting for confounders, SMI (adjusted OR 1.03, 95% CI 0.97-1.09) was not independently associated with ADL disability; however, SMD (adjusted OR 0.94, 95% CI 0.88-0.99), IMAT (adjusted OR 1.11, 95% CI 1.03-1.20), and IMAT% (adjusted OR 1.09, 95% CI 1.02-1.16) were independently associated with ADL disability. Subgroup analysis found similar results in men; however, none of these indicators were independently associated with ADL disability in women. Conclusion: Trunk muscle quality indicators (SMD, IMAT, and IMAT%) measured by chest CT images, but not SMI, are independently associated with ADL disability in a single-center study population of older inpatients, especially in men. Further research is necessary to validate our findings.

Comparison of muscle mass and quality between metabolically healthy and unhealthy phenotypes

OBJECTIVE

The aim of this study was to examine whether higher skeletal muscle mass is associated with a metabolically healthy phenotype and whether muscle quality affects metabolic health.

METHODS

This cross-sectional analysis included 20,659 participants (7,966 women) who underwent abdominal computed tomography scans during health checkups. The total abdominal muscle area (TAMA) on the third lumbar vertebral level was demarcated. Intermuscular adipose tissue and skeletal muscle area were measured. The skeletal muscle area was divided into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). The NAMA/TAMA index was calculated. The metabolically unhealthy phenotype was defined as having two or more components of metabolic syndrome or the presence of hypertension or diabetes.

RESULTS

TAMA and skeletal muscle area were not significantly different or even lower in metabolically healthy phenotypes compared with metabolically unhealthy phenotypes. However, metabolically healthy phenotypes had significantly higher NAMA (except in women with obesity) and NAMA/TAMA index than in the metabolically unhealthy phenotypes. In people without obesity, lower NAMA/TAMA index was independently associated with higher risk of the metabolically unhealthy phenotype in the fully adjusted model.

CONCLUSIONS

The metabolically healthy phenotypes had more good-quality muscles than did the metabolically unhealthy phenotypes. These results suggest that not only muscle mass but also muscle quality (i.e., degree of myosteatosis) are associated with metabolic health.