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Updated: May 18, 2026
Decellularization-Based Quantification of Skeletal Muscle Fatty Infiltration
Published on: June 9, 2023
Clinical Sensitivity of Sub-millimetre-resolution Definite Versus Thin Inter-/Intramuscular Fat Streaks from Calf and
Kenneth Tam1, Si Wen Liu2,3, Sarah Costa Ianes3
1Department of Neurobiology, Physiology, and Behavior, University of California Davis, Davis, CA, USA.
Abstract:
Sub-millimetre resolution magnetic resonance imaging (MRI) reveal detailed patterns of inter- and intra-muscular fat (IMF) enabled by recent segmentation algorithms. However, clinical relevance of finer IMF streaks, beyond definite deposits, remains unclear. T1-weighted spin-echo MRI was acquired in the AMBERS (Appendicular Muscle and Bone Extension Research Study; calves from community-based females) and OAI (Osteoarthritis Initiative; thighs from disease-focused males and females) cohorts, including adults 45-85 years old. Thigh and calf MR images were segmented using the iterative threshold-seeking algorithm to quantify definite versus thinner streaks, with 3D connectivity verification, and partial volume correction. Absolute and relative IMF volumes were derived. Lower-extremity physical function and activities of daily living (ADL) were assessed contemporaneously. Clinical sensitivity was evaluated using multivariable linear regression relating IMF volumes to demographics, physical function, and ADLs. Among 385 adults (89% female; age 71.6 ± 7.6 years; body mass index (BMI) 28.1 ± 4.9 kg/m2; IMF% 19.75 ± 4.1%), higher IMF% was associated with older age (1.5-2.7% per 10 years), female sex (3.8 [1.8, 5.8]%), and higher BMI (1.9-6.2% per 10 kg/m2). Negative associations with physical function and ADLs were strongest for definite IMF streaks, with more consistent effects at the calf than thigh. Thinner IMF streaks were less sensitive to physical function but unexpectedly showed beneficial links to ADL. High-resolution MRI-derived IMF is clinically sensitive to demographics and physical functional. Thinner IMF streaks, potentially representing greater dynamics of muscle fat turnover, may confer benefits for daily function, yet most clinical protocols fail to capture them.
Insights
High-resolution MRI reveals detailed intra-muscular fat (IMF) patterns. While definite IMF deposits impact physical function, thinner IMF streaks may benefit daily activities, suggesting current clinical protocols miss crucial details.
Area of Science:
- Biomedical Imaging
- Musculoskeletal Research
- Gerontology
Background:
- Sub-millimeter resolution magnetic resonance imaging (MRI) enables detailed visualization of inter- and intra-muscular fat (IMF).
- The clinical relevance of finer IMF streaks, beyond definite deposits, remains largely unclear.
- Existing segmentation algorithms provide new capabilities for IMF quantification.
Purpose of the Study:
- To investigate the clinical relevance of different intra-muscular fat (IMF) patterns, including finer streaks, in relation to physical function and daily activities.
- To evaluate the sensitivity of high-resolution MRI-derived IMF measures to demographic factors and functional outcomes.
- To compare the associations of definite IMF deposits versus thinner IMF streaks with physical function and activities of daily living (ADL).
Main Methods:
- T1-weighted spin-echo MRI was acquired from the AMBERS and OAI cohorts, comprising adults aged 45-85 years.
- Thigh and calf MR images were segmented using an iterative threshold-seeking algorithm to quantify definite IMF deposits and thinner streaks, with 3D connectivity verification and partial volume correction.
- Absolute and relative IMF volumes were derived, and associations with demographics, lower-extremity physical function, and ADLs were assessed using multivariable linear regression.
Main Results:
- Higher overall IMF percentage was associated with older age, female sex, and higher body mass index (BMI).
- Negative associations with physical function and ADLs were strongest for definite IMF streaks, particularly in the calf.
- Thinner IMF streaks showed weaker associations with physical function but unexpectedly beneficial links to ADLs.
Conclusions:
- High-resolution MRI-derived IMF is clinically sensitive to demographic factors and physical function.
- Thinner IMF streaks, potentially indicating dynamic muscle fat turnover, may offer benefits for daily function.
- Current clinical MRI protocols may not capture the full spectrum of IMF, potentially overlooking beneficial fat patterns.
