Do Ultrasound Based Quantitative Hepatic Fat Content Measurements Have Differences Between Respiratory Phases?

Area of Science:

• Medical Imaging
• Hepatology
• Biophysics

Background:

• Ultrasound-based tools quantify hepatic fat content in non-alcoholic fatty liver disease (NAFLD) using attenuation coefficient (AC) and scatter distribution coefficient (SDC).
• The influence of respiratory phase on these quantitative ultrasound measurements is currently unknown.

Purpose of the Study:

• To compare AC and SDC measurements obtained during peak inspiration and end expiration in NAFLD patients.
• To determine if respiratory variations affect the accuracy of ultrasound-based hepatic fat quantification.

Main Methods:

• AC and SDC values were measured in 50 NAFLD patients using Tissue Attenuation Imaging (TAI) and Tissue Scatter Distribution Imaging (TSI).
• Five measurements were taken at each respiratory phase (peak inspiration, end expiration), and median values were recorded.
• Statistical comparison was performed using the Wilcoxon signed rank test, with subgroup analyses based on BMI.

Main Results:

• Median AC values were 0.87 dB/cm/MHz (inspiration) and 0.89 dB/cm/MHz (expiration).
• Median SDC values were 97.91 (inspiration) and 96.62 (expiration).
• No significant differences in AC or SDC were found between respiratory phases, except for AC in the BMI <30 kg/m² subgroup.

Conclusions:

• Respiratory phase does not impact SDC measurements in NAFLD patients.
• AC measurements are significantly affected by respiratory phase in NAFLD patients with BMI <30 kg/m², but not in those with BMI ≥30 kg/m².