Impact of Respiratory Motion on the Quantification of Pediatric Hepatic Steatosis Using Two Different Ultrasonography Machines.

Purpose: This study aimed to investigate the effect of respiratory motion on hepatic steatosis quantification using ultrasound attenuation imaging (ATI) or ultrasound-guided attenuation parameter (UGAP) in pediatric patients.

Materials and methods: Pediatric patients (aged ≤18 years) who underwent liver ultrasonography (US) with ATI or UGAP between May 2022 and February 2023 were included retrospectively. Median, interquartile range (IQR), and IQR/median values were calculated in both free-breathing (FB) and breath-holding (BH) states. Subjects were divided into normal and fatty liver groups according to grayscale US. Wilcoxon signed rank test, intraclass correlation coefficient (ICC), and linear regression test were used.

Results: A total of 83 patients (M:F=46:37, median age 10 years, range 6-17 years) was included, with 55 patients in the ATI group and 28 patients in the UGAP group. The measured values of ATI and UGAP were not significantly different between FB and BH. The ICC values between FB and BH states were 0.950 [95% confidence interval (CI) 0.916-0.971] for median ATI and 0.786 (95% CI 0.591-0.894) for median UGAP. FB and BH status did not significantly affect the median ATI and UGAP (p=0.852, 0.531, respectively). The IQR/median value showed a significant association with age only in the FB status of the normal group using ATI (β= -0.014, p=0.042).

Conclusion: Respiratory motion does not significantly affect the measurement of ATI or UGAP. Median ATI value showed excellent agreement in FB and BH status, while UGAP showed good agreement. Younger age may affect measurement variability in FB status of the normal group using ATI.