Ectopic fat in liver and skeletal muscle is associated with shorter overall survival in patients with colorectal liver metastases

BACKGROUND

Myosteatosis has been associated with shorter overall survival in cancer patients. The increase in ectopic fat might not be limited to skeletal muscle only and might also extend to other sites such as the liver, resulting in non-alcoholic fatty liver disease (NAFLD). In this study, we assessed the relationship between myosteatosis and NAFLD and their association with overall survival in patients with colorectal liver metastases undergoing partial hepatectomy.

METHODS

Patients were selected from a prospective cohort of 289 consecutive patients with colorectal liver metastases. All patients with a preoperative computed tomography (CT)-scan and liver biopsy obtained during surgery were included. If available a second pre-operative CT scan was used to calculate changes in body composition over time. Muscle radiation attenuation was defined as the average Hounsfield units on CT of all muscle tissue at the L3 level. Liver biopsies were graded by a liver pathologist using the steatosis, activity, and fibrosis scoring system for NAFLD.

RESULTS

Two-hundred and eighteen patients had an available liver biopsy of which 131 patients had two available pre-operative CT scans with an average time interval of 3.2 months. One-hundred and thirty-five (62%) biopsies were classified as NAFLD. In multivariable Cox-regression analysis, NAFLD [hazard ratio (HR): 1.8, 95%-confidence interval (CI) 1.0-3.0, P = 0.037], increase in myosteatosis (HR 1.8, 95%-CI 1.1-2.9, P = 0.018), and skeletal muscle loss (HR 1.7, 95%-CI 1.0-2.9, P = 0.035) were independently associated with shorter overall survival while high visceral adipose tissue fat content was associated with longer overall survival (HR: 0.7, 95%-CI 0.5-0.9, P = 0.014).

CONCLUSIONS

Ectopic fat content of liver as well as skeletal muscle tissue is independently associated with shorter overall survival in patients with colorectal liver metastases, while increased visceral adipose tissue fat content is associated with longer overall survival.

The reproducibility of skeletal muscle signal intensity on routine magnetic resonance imaging in Crohn's disease

BACKGROUND AND AIM

Myosteatosis is a prognostic factor in cancer and liver cirrhosis. It can be determined noninvasively using computed tomography or, as shown recently, by magnetic resonance (MR) imaging. The primary aim was to analyze the reproducibility of skeletal muscle signal intensity on routine MR-enterographies, as indicator of myosteatosis, in Crohn's disease (CD) and to explore the association between skeletal muscle signal intensity at diagnosis with time to intestinal resection.

METHODS

CD patients undergoing MR-enterography within 6 months from diagnosis and having a maximum of 5 years follow-up were included. Skeletal muscle signal intensity was analyzed on T1-weighted fat-saturated post-contrast images. Intra-observer and inter-observer reproducibilities were assessed by intra-class correlation coefficient and Cohen's kappa. Intra-observer and inter-observer variabilities were determined by Pearson correlation coefficient and displayed by Bland-Altman plots. Time to intestinal resection was studied by Kaplan-Meier analysis.

RESULTS

Median time between diagnosis and MR-enterography was 5 weeks (inter-quartile range 1-9) in 35 CD patients. Skeletal muscle signal intensity showed good intra-class correlation and substantial agreement (for intra-observer, intraclass correlation coefficient = 0.948, κ = 0.677; and inter-observer reproducibility, intraclass correlation coefficient = 0.858, κ = 0.622). Resection free survival was shorter in the low skeletal muscle signal intensity group (P = 0.037).

CONCLUSION

Skeletal muscle signal intensity on routine MR-enterographies is reproducible and was associated with unfavorable disease outcome, indicating potential clinical relevance.

Myosteatosis is associated with poor physical fitness in patients undergoing hepatopancreatobiliary surgery

BACKGROUND

Body composition assessment, measured using single-slice computed tomography (CT) image at L3 level, and aerobic physical fitness, objectively measured using cardiopulmonary exercise testing (CPET), are each independently used for perioperative risk assessment. Sarcopenia (i.e. low skeletal muscle mass), myosteatosis [i.e. low skeletal muscle radiation attenuation (SM-RA)], and impaired objectively measured aerobic fitness (reduced oxygen uptake) have been associated with poor post-operative outcomes and survival in various cancer types. However, the association between CT body composition and physical fitness has not been explored. In this study, we assessed the association of CT body composition with selected CPET variables in patients undergoing hepatobiliary and pancreatic surgery.

METHODS

A pragmatic prospective cohort of 123 patients undergoing hepatobiliary and pancreatic surgery were recruited. All patients underwent preoperative CPET. Preoperative CT scans were analysed using a single-slice CT image at L3 level to assess skeletal muscle mass, adipose tissue mass, and muscle radiation attenuation. Multivariate linear regression was used to test the association between CPET variables and body composition. Main outcomes were oxygen uptake at anaerobic threshold ( V̇ O₂ at AT), oxygen uptake at peak exercise ( V̇ O₂ peak), skeletal muscle mass, and SM-RA.

RESULTS

Of 123 patients recruited [77 men (63%), median age 66.9 ± 11.7, median body mass index 27.3 ± 5.2], 113 patients had good-quality abdominal CT scans available and were included. Of the CT body composition variables, SM-RA had the strongest correlation with V̇ O₂ peak (r = 0.57, P < 0.001) and V̇ O₂ at AT (r = 0.45, P < 0.001) while skeletal muscle mass was only weakly associated with V̇ O₂ peak (r = 0.24, P < 0.010). In the multivariate analysis, only SM-RA was associated with V̇ O₂ peak (B = 0.25, 95% CI 0.15-0.34, P < 0.001, R²  = 0.42) and V̇ O₂ at AT (B = 0.13, 95% CI 0.06-0.18, P < 0.001, R²  = 0.26).

CONCLUSIONS

There is a positive association between preoperative CT SM-RA and preoperative physical fitness ( V̇ O₂ at AT and at peak). This study demonstrates that myosteatosis, and not sarcopenia, is associated with reduced aerobic physical fitness. Combining both myosteatosis and physical fitness variables may provide additive risk stratification accuracy and guide interventions during the perioperative period.