Ultrasound evaluation of the fibrosis stage in chronic liver disease by the simultaneous use of low and high frequency probes

Abstract

A liver biopsy is currently considered the definitive diagnostic modality for establishing the severity of hepatic fibrosis. We analysed the diagnostic sensitivity and accuracy of ultrasound (US) using both low frequency and high frequency probes as a repeatable, inexpensive, and reliable method to determine the fibrosis stage in chronic liver disease and then compared our results with the histological findings. A total of 103 patients with chronic liver disease (60 males and 43 females, average age 51 years old) who had undergone both a liver biopsy and US with 2-5 MHz frequency and 5-12 MHz frequency probes were prospectively evaluated in this study. An US scoring system using both the low frequency and high frequency probes was performed by evaluating the edge, surface and parenchymal texture of the liver. Each score was obtained by evaluating three parameters; the bluntness of the liver edge, the irregularity of the surface and the coarseness of the parenchymal texture were evaluated and then compared with the histological findings. The US scores of the liver edge (rs: 0.6668), liver surface (rs: 0.9007) and liver parenchymal texture (rs: 0.8853) correlated significantly with the fibrosis stage obtained based on the biopsy findings. The accumulated US scores of these three parameters, however, was found to be the most reliable indicator (rs: 0.9524). Patients with an accumulated score of 6.5 or more were all found to have fibrosis stage 4 in which the accuracy of our scoring system for correctly predicting cirrhosis was found to be 100% sensitive. When an accumulated US score of 3 was interpreted to indicate mild fibrosis (a fibrosis score of 0 or 1), all 42 patients with stage 0 or 1 fibrosis were found to have an accumulated US score of 3 or less (a probability of 100%) and 42 of 53 patients with a score of 3 or less were found to have stage 0 or 1 fibrosis (specificity of 79.2%). An ultrasound evaluation of the liver fibrosis stage based on the scoring system using both low and high frequency probes was found to be a reliable and effective alternative to the histological staging in chronic liver diseases.