Quantification of hepatic steatosis with ultrasound: promising role of attenuation imaging coefficient in a biopsy-proven cohort

Objectives To prospectively assess the role of the US attenuation imaging coefficient (AC) for the diagnosis and quantification of hepatic steatosis. Methods One hundred and one patients underwent liver biopsy and US-AC measurement on the same day. Liver steatosis was graded according to biopsy as absent (S0 < 5%), mild (S1 5–33%), moderate (S2 33–66%), or severe (S3 > 66%); liver fibrosis was graded from F0 to F4. The correlation between AC and steatosis on pathology (%) was calculated using the Pearson correlation coefficient. The Student t or Mann–Whitney U test was used to compare continuous variables and ROC curve analysis was used to assess diagnostic performance of AC in diagnosing steatosis. Results Overall, 43 (42%), 35 (35%), 12 (12%), and 11 (11%) patients were classified as S0, S1, S2, and S3, respectively. The AC was positively correlated with steatosis as a continuous variable (%) on pathology ( r = 0.58, p < 0.01). Patients with steatosis of any grade had a higher AC than those without steatosis (mean 0.77 ± 0.13 vs. 0.63 ± 0.09 dB/cm/MHz, respectively; p < 0.01, AUROC = 0.805). Patients with S2–S3 had a higher AC than patients with S0–1 (0.85 ± 0.11 vs. 0.67 ± 0.11 dB/cm/MHz, respectively; p < 0.01, AUROC = 0.892). AC > 0.69 dB/cm/MHz had a sensitivity and specificity of 76% and 86%, respectively, for diagnosing any grade of steatosis (S1–S3), and AC > 0.72 dB/cm/MHz had a sensitivity and specificity of 96% and 74%, respectively, for diagnosing S2–S3. The presence of advanced fibrosis (F3–F4) did not affect the calculated AC. Conclusions The attenuation imaging coefficient is a promising quantitative technique for the non-invasive diagnosis and quantification of hepatic steatosis. Key Points • Measurement of the attenuation coefficient is achieved with a very high rate of technical success. • We found a significant positive correlation between the attenuation coefficient and the grade of steatosis on pathology. • The attenuation imaging coefficient is a promising quantitative technique for the noninvasive diagnosis and quantification of hepatic steatosis.