Exploratory associations between CT-derived body composition and MRI-based infrapatellar fat pad profiles with age-stratified analyses: a retrospective cross-sectional study.
Authors
Affiliations (5)
Affiliations (5)
- Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, 211, Eonju-ro, Gangnam-gu, Seoul, 06273, Republic of Korea.
- Institute for Innovation in Digital Healthcare, Yonsei University, Seoul, Republic of Korea.
- Department of Medical Device Engineering and Management, The Graduate School, Yonsei University College of Medicine, Seoul, Republic of Korea.
- Department of Integrative Medicine, The Graduate School, Yonsei University College of Medicine, Seoul, Republic of Korea.
- Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, 211, Eonju-ro, Gangnam-gu, Seoul, 06273, Republic of Korea. [email protected].
Abstract
Osteoarthritis is increasingly recognized as a whole-joint disorder with metabolic and inflammatory components. The infrapatellar fat pad (IPFP) is a metabolically active intra-articular tissue, but the systemic factors associated with quantitative MRI-based IPFP profiles remain incompletely understood. This retrospective cross-sectional study included 67 knees from 64 adults who underwent knee MRI, ipsilateral knee radiography, and abdominopelvic CT within 3 months. IPFP cross-sectional area (IPFP area) and log-transformed normalized signal intensity (Norm-P) were assessed on sagittal fat-suppressed proton density- or T2-weighted MRI sequences. CT-derived body composition metrics, including L3-based total muscle area and L3-based total fat area, were obtained using automated deep learning-based software. Associations were evaluated using Pearson correlation and multivariable linear regression adjusted for age, sex, body mass index, and Kellgren-Lawrence grade. Interaction analyses were performed to assess effect modification by age and sex, with exploratory subgroup analyses stratified by age (< 50 vs. ≥50 years) and sex. In the overall cohort, CT-derived body composition metrics were not significantly associated with IPFP area or Norm-P after multivariable adjustment. Interaction analyses did not show significant effect modification by age or sex. In exploratory age-stratified analyses, L3-based total fat area was associated with log(Norm-P) in the older subgroup (P = 0.039). A 10 cm² increase in L3-based total fat area was associated with an approximately 3.9% [95% CI, 0.2%-7.7%] higher Norm-P in the older subgroup. No significant associations were observed in the younger subgroup or in sex-stratified analyses after multivariable adjustment. In this exploratory retrospective cross-sectional study, CT-derived body composition metrics were not significantly associated with quantitative MRI-based IPFP profiles in the overall cohort, and interaction analyses did not confirm significant effect modification by age or sex. Although L3-based total fat area showed an association with Norm-P in the older subgroup, this finding should be interpreted cautiously and requires validation in larger prospective cohorts.