Sex-specific CT-derived reference cutoffs for body composition in healthy Brazilian adults: a multicenter study

Area of Science:

• Radiology and Imaging
• Human Physiology
• Body Composition Analysis

Background:

• Accurate assessment of skeletal muscle and adipose tissue using computed tomography (CT) is crucial for understanding body composition.
• Population-specific reference values for CT-derived body composition metrics are limited, hindering standardized clinical and research applications.

Purpose of the Study:

• To establish sex- and region-specific CT-derived reference cutoff values for body composition.
• To provide standardized reference data for skeletal muscle area (SMA), skeletal muscle density (SMD), and adipose tissue compartments.

Main Methods:

• A multicenter cross-sectional study involving 1,621 adults (818 males, 803 females).
• Reference cutoffs were derived from a subgroup of 650 young adults (18-39 years) with normal BMI (18.5-24.9 kg/m²).
• Noncontrast CT scans at the third lumbar vertebra were analyzed to quantify SMA, SMD, and adipose compartments; cutoffs were defined as 1 or 2 standard deviations from the mean.

Main Results:

• Sex-specific low muscle cutoff values were established: e.g., for males, SMA < 149 cm², SMI < 49 cm²/m², SMD < 42 HU; for females, SMA < 98 cm², SMI < 38 cm²/m², SMD < 38 HU.
• Sex-specific high visceral adipose tissue cutoff values were determined: > 151 cm² in males and > 90 cm² in females.
• Muscle parameters decrease with age, while adiposity increases, with males showing higher muscle indices than females.

Conclusions:

• The study successfully established standardized CT-based reference values for body composition.
• These reference values are essential for accurate clinical diagnosis and research in diverse populations.
• The findings highlight age and sex differences in body composition metrics derived from CT scans.