Ultrasound attenuation coefficient of the liver and spleen in adults: A preliminary observation

Abstract

Objectives: The aim of the study was to assess ultrasound attenuation coefficient (AC) in adult liver and spleen.

Methods: After obtaining IRB approval and written informed consent, liver AC and spleen AC were measured, and AC liver to spleen ratio (AC L/S = AC _liver/AC _spleen) was calculated in 36 adult volunteers (16 men and 20 women, mean age 50y). Based on magnetic resonance imaging derived proton density fat fraction (MRI-PDFF), the participants were divided into normal liver (MRI-PDFF <5%) and steatotic liver (MRI-PDFF ≥5%) groups. Difference in AC between the liver and spleen in each group and differences in liver AC and AC L/S between the two groups were analyzed using two-tailed t-test. Diagnostic performance of liver AC and AC L/S for determining hepatic steatosis was tested by area under receiver operating characteristic curve (AUROC).

Results: There were 12 normal livers and 24 steatotic livers in the study. The difference in AC between liver and spleen was significant in steatotic liver group (p < 0.001) whereas it was not in normal liver group (p > 0.05). Differences in liver AC and AC L/S between the two groups were significant (p < 0.001) whereas difference in spleen AC was not (p > 0.05). AUROC of liver AC and AC L/S for determining ≥ mild hepatic steatosis was 0.90 and 0.97, respectively.

Conclusion: Liver AC increased, and spleen AC did not change following the development of hepatic steatosis. The feasibility of AC L/S in determining hepatic steatosis needs further investigation.

Keywords: Attenuation coefficient; Hepatic steatosis; Liver-spleen ratio; Nonalcoholic fatty liver disease; Ultrasound.