Body composition measurement using computed tomography: Does the phase of the scan matter?

Area of Science:

• Radiology
• Medical Imaging
• Body Composition Analysis

Background:

• Accurate body composition analysis using computed tomography (CT) is crucial for clinical assessments.
• The influence of intravenous contrast agents on CT-based body composition measurements is not fully understood.
• Standardization of CT imaging protocols is essential for reliable and reproducible body composition data.

Purpose of the Study:

• To investigate the methodological impact of intravenous contrast on body composition variables derived from CT imaging.
• To compare body composition metrics obtained from noncontrast, arterial, and portovenous phase CT scans.
• To assess the effect of scan phase on skeletal muscle index (SMI), fat mass (FM), and fat-free mass (FFM).

Main Methods:

• Analysis of triphasic abdominal CT scans (noncontrast, arterial, portovenous) from 111 patients.
• Utilized SliceOmatic software for quantitative analysis at the L3 vertebral level.
• Measured skeletal muscle index (SMI), fat mass (FM), fat-free mass (FFM), and skeletal muscle Hounsfield units (SMHU).

Main Results:

• Mean skeletal muscle Hounsfield units (SMHU) varied significantly across scan phases, increasing with contrast.
• Fat mass (FM) was significantly lower in arterial and portovenous phases compared to noncontrast scans.
• Fat-free mass (FFM) and skeletal muscle index (SMI) showed no significant differences between scan phases.

Conclusions:

• Standardization of CT scan phase is recommended for defining and analyzing myosteatosis.
• While contrast affects FM and SMHU, its impact on FFM and SMI appears minimal.
• Further research is needed to determine the clinical significance of these phase-dependent differences in outcome prediction.