Association between 3 D CT-based volumetric fat infiltration of lumbar paraspinal muscles and bone mineral density: a clinical study.
TL;DR
Lumbar paraspinal muscle adiposity, particularly in the L3 multifidus, is inversely associated with BMD in postmenopausal women, and L3 multifidus FIR is a statistically significant auxiliary imaging metric for proactive osteoporosis screening and the assessment of osteosarcopenia risk.
Abstract
Objective
This study investigated the association between the fat infiltration rate (FIR) of lumbar paraspinal muscles-specifically the multifidus, erector spinae, and psoas major-and bone mineral density (BMD) in postmenopausal women. By examining muscular and segmental (L2-L4) adiposity variations, we aimed to identify imaging biomarkers for early osteoporosis detection and to inform integrated "bone-muscle" therapeutic strategies.
Methods
A retrospective analysis was performed on 120 postmenopausal women who underwent dual-energy X-ray absorptiometry (DXA) and lumbar computed tomography (CT) between 2024 and 2025. Participants were categorized into three cohorts-normal bone mass, osteopenia, and osteoporosis-based on DXA T-scores. Demographic data, including BMI, were recorded and subsequently utilized as a covariate in the regression models to ensure robust statistical adjustment. The L2-L4 paraspinal musculature was automatically segmented in 3D using 3D Slicer software with the MuscleMap plug-in to determine the FIR for each muscle group. Data normality was assessed using Shapiro-Wilk tests, while inter-group differences were compared via one-way ANOVA or Kruskal-Wallis H tests. Correlations were quantified using Pearson or Spearman analyses.
Results
Age was comparable across groups ( P = 0. 160 ), but BMI and average BMD differed significantly. Multifidus FIR showed a significant inverse correlation with BMD ( P < 0. 001 ). After adjusting for BMI, multifidus fat infiltration remained an independent predictor of BMD. At the segmental level, the L3 multifidus displayed the greatest inter-group variance and the strongest negative correlation with BMD ( r = -0. 689, P < 0. 001 ).
Conclusions
Lumbar paraspinal muscle adiposity, particularly in the L3 multifidus, is inversely associated with BMD in postmenopausal women. Consequently, L3 multifidus FIR is a statistically significant auxiliary imaging metric for proactive osteoporosis screening and the assessment of osteosarcopenia risk.