Abstract / Summary
Abstract Background Bone marrow adipose tissue (BMAT) is a metabolically active fat depot implicated in skeletal aging and systemic metabolism. While chemical shift-encoding MRI enables noninvasive quantification of bone marrow fat fraction (BMFF), current knowledge of vertebral BMAT is largely limited to small cohorts or restricted anatomical regions. Purpose To characterize the spatial distribution of vertebral bone marrow fat fraction across the spine and determine region-specific associations with age and sex in a population-based cohort. Materials and methods In this retrospective study, MRI data from 82,920 UK Biobank participants recruited between 2006 and 2010 were analyzed. The baseline case subset ( n = 81,318) had a mean age of 54.8 ± 7.6 years, and 42,113/81,318 (51.8%) were female. Automated vertebral body segmentation enabled voxel-wise BMFF quantification using Dixon MRI. Vertebra- and region-level BMFF metrics were derived. Associations with age and sex were assessed using region-specific linear regression. Results Vertebral BMAT demonstrated a non-linear cranio-caudal pattern. Mean BMFF was ~ 39% in the cervical, ~ 55% in the thoracic, ~ 45% in the lumbar spine, and ~ 70% in the sacrum. BMAT increased with age in all regions (all p < 0.001; increase per decade: cervical 3.33%, thoracic 3.41%, lumbar 2.95%, sacral 3.83%). Females exhibited higher BMFF than males across all regions (all p < 0.001). The overall spatial pattern remained consistent across age groups and sexes. Conclusion Vertebral BMAT exhibits a structured, non-linear spatial distribution with region-specific age- and sex-dependent patterns. This population-based atlas provides normative reference data supporting region-specific BMAT assessment in skeletal and metabolic disease.