Fat Content Quantification with US Attenuation Coefficient: Phantom Correlation with MRI Proton Density Fat Fraction.

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biophysics

Background:

• Accurate quantification of tissue fat concentration is crucial for diagnosing and monitoring various medical conditions.
• Magnetic Resonance Imaging (MRI) provides a reliable measure of fat fraction (MRI-PDFF), but its accessibility can be limited.
• Ultrasound (US) offers a more portable and cost-effective imaging modality, with its attenuation coefficient (AC) showing potential for fat quantification.

Purpose of the Study:

• To evaluate the consistency and reproducibility of attenuation coefficient (AC) measurements using different commercial ultrasound (US) devices.
• To investigate the relationship between US-derived AC values and MRI-derived proton density fat fraction (MRI-PDFF).
• To derive a conversion equation for estimating fat concentration from US AC measurements.

Main Methods:

• Twelve phantoms with varying fat proportions (0-100%) were created.
• Attenuation coefficients (AC) were measured using three commercial ultrasound systems: attenuation imaging (ATI), ultrasound attenuation analysis (USAT), and US-guided attenuation parameter (UGAP).
• MRI-PDFF measurements were obtained for comparison, and linear correlation analysis was performed to establish relationships and derive a conversion formula.

Main Results:

• Ultrasound AC measurements demonstrated high consistency and reproducibility, with inter- and intra-operator intraclass correlation coefficients (ICCs) ranging from 0.989 to 0.995.
• Significant linear relationships were found between ultrasound attenuation parameters and phantom fat concentration (r = 0.938-0.986) and between ultrasound attenuation parameters and MRI-PDFF values (r = 0.922-0.982).
• A conversion formula was derived: US (dB/cm/MHz) = 0.501 + 0.012 MRI-PDFF (%) for fat proportions ≤ 50%.

Conclusions:

• Commercial ultrasound devices show significant diagnostic value for quantifying fat concentrations with good consistency.
• The established linear relationship between ultrasound AC and MRI-PDFF supports the development of a practical conversion formula.
• This research paves the way for wider clinical application of ultrasound in non-invasive fat quantification.