Reproducibility and accuracy of a pocket-size ultrasound device in assessing liver steatosis

Abstract

Background: This diagnostic prospective study compared the feasibility and diagnostic accuracy of Pocket-size Ultrasound Devices (PUDs) against standard ultrasound (US) in detecting liver steatosis using the controlled attenuation parameter (CAP) and liver biopsy as reference standards.

Materials and methods: Consecutive patients with chronic liver diseases were assessed for the presence of steatosis using PUD and US. A CAP cut-off value >275 dB/m was applied to establish ≥S1. A 26-patient subgroup underwent liver biopsy. PUD reproducibility was evaluated using Cohen's k statistic. Diagnostic accuracy of PUD and US was given as Sensibility (Sn), Specificity (Sp), Positive and Negative Predictive Values (PPV, NPV), positive and negative Likelihood Ratio (LR+, LR-).

Results: 81 consecutive patients (69% males) with multiple etiologies were enroled. PUD inter-observer agreement was good (k 0.77, 95%CI 0.62-0.93). PUD and US identified ≥S1 according to CAP values respectively with Sn 0.87, Sp 0.61, PPV 0.49, NPV 0.91, LR+ 2.04, LR- 0.07, AUROC 0.74 and Sn 0.96, Sp 0.54, PPV 0.47, NPV 0.97, LR+ 2.10, LR- 0.07, AUROC 0.75.

Conclusions: PUD shows good reproducibility and diagnostic accuracy in ruling liver steatosis out, representing a useful point-of-care tool to avail of hepatologists interested in excluding NAFLD, but with basic US skills.

Keywords: Controlled-attenuation parameter; Liver biopsy; Non-alcoholic fatty liver disease; Pocket size ultrasound devices; Steatosis; Ultrasound; Vibration-controlled transient elastography.