Ultrasound structure function for quantitative assessment of steatotic liver disease based on total severity score

Quantitative ultrasound parameters offer effective tools to evaluate microstructural changes in liver tissue and noninvasively assess tissue health. We examined the relationship between steatotic liver disease severity, measured by the Total Severity Score (TSS), and the structure function (SF), a frequency-dependent ultrasound backscatter metric. TSS was calculated on a 0-14 scale from histological evaluation by a pathologist of fibrosis, inflammation, and steatosis in hematoxylin and eosin-stained liver slides. A total of 274 regions of interest (ROIs) were examined from histopathology liver specimens acquired from 49 human subjects. SF was calculated for every ROI over a spatial frequency range of 3-80 MHz using histology-determined cell nuclei positions. Results revealed a strong relationship between SF and TSS across all analyzed ROIs, and distinct frequency-dependent patterns emerged across TSS groups. Statistical analysis showed significant differences between TSS 0 and TSS 1-3 for the frequency range of 4.5 to 9.0 MHz, and between TSS 1-3 and TSS 4-6 for the frequency ranges of 3.0 to 9.0 MHz and 32.5 to 80.0 MHz. TSS groups 4-6 and 7-14 did not differ significantly, indicating a possible plateau in ultrasound response at later disease stages. These findings help lay the foundation for establishing SF as a potential ultrasonic biomarker for identifying and distinguishing steatotic liver disease stages in vivo.