Associations of MRI-derived paraspinal IMAT and LMM with cardiometabolic risk factors: results from a German cohort

BACKGROUND: Increasing evidence shows that intermuscular adipose tissue (IMAT) and lean muscle mass (LMM) influence cardiometabolic health; however, their independent and/or combined associations with cardiovascular risk in individuals without pre-existing conditions remain unclear. PURPOSE: To assess whether IMAT and LMM are associated with cardiometabolic risk factors in individuals without pre-existing conditions. MATERIALS AND METHODS: A total of 11 348 participants (6460 [56.9%] men; median age, 43.0 years; IQR, 33.5–52.5 years) without any known pre-existing conditions underwent whole-body 3-T MRI as part of a prospective multicenter population study (German National Cohort, or NAKO). LMM and IMAT were quantified on MRI-based paraspinal muscle segmentations with a deep learning model. Cardiometabolic risk factors (hypertension, dysglycemia, and atherogenic dyslipidemia) were defined on the basis of laboratory test results and clinical examinations. Age- and sex-corrected z scores of LMM and IMAT were calculated. Associations of LMM and IMAT percentage with physical activity and cardiometabolic risk factors were examined with univariable and multivariable analyses. RESULTS: The percentage of IMAT increased with age and was greater in women, whereas LMM decreased with age and was lower in women. After adjustments for age, sex, and study site, increased IMAT was associated with increased odds of hypertension (odds ratio [OR], 1.67; 95% CI: 1.49, 1.86; P < .001), atherogenic dyslipidemia (OR, 1.82; 95% CI: 1.65, 2.00; P < .001), and dysglycemia (OR, 0.51; 95% CI: 0.35, 0.76; P = .009) in both sexes, whereas increased LMM was associated with decreased odds of all risk factors (dysglycemia: OR, 0.51; 95% CI: 0.35, 0.76; P = .009; atherogenic dyslipidemia: OR, 0.49; 95% CI: 0.39, 0.62; P < .001; hypertension: OR, 0.34; 95% CI: 0.24, 0.48; P < .001) in male participants only. Across z score combinations, participants with higher IMAT and lower LMM showed the highest prevalence of cardiometabolic risk factors. CONCLUSION: IMAT and LMM, assessed on MRI scans, were independently associated with cardiometabolic risk factors in individuals without pre-existing conditions.