Evaluation of acoustic radiation force impulse elastography (ARFI) in the diagnosis of hepatic fibrosis and portal hypertension

Abstract

Transient elastography by fibroscan is widely used as non-invasive marker for diagnosis of liver fibrosis. Fibroscan is limited in accuracy in patients with acute hepatitis, ascites and patients with BMI >30 and it requires separate equipment. ARFI is a new way of assessing liver fibrosis and is incorporated in ultrasound machine. In a prospective study we evaluated utility of ARFI in 181 consecutive patients undergoing liver biopsy and assessed misclassification rate of fibrosis in patients with acute hepatitis ascites, ascites and patients with BMI >25. Material&method: 181 consecutive patients (males 60%, age mean ±SD 46.04±13.34 years) undergoing liver biopsy were evaluated for ARFI by Acuson S2000, Siemens ultrasonography machine. In addition to abdominal ultrasound with doppler examination, patients were subjected to 10 acquisitions of ARFI were obtained between ribs of liver from right lobe in dorsal decubitus position and momentary breath holding. All the patients were evaluated with appropriate clinical history, physical examination, laboratory evaluation, endoscopy and other ancillary tests as required. Major indications for liver biopsy were autoimmune liver disease (38), non-alcoholic fatty liver disease (24), cryptogenic liver disease (10), noncirrhotic portal hypertension (27) and viral hepatitis (17). Liver biopsy was graded by single pathologist blind folded by Metavir classification. Aspartate aminotransferase to platelet ratio index (APRI) was calculated in each patient. ARFI values for liver and spleen were correlated with presence and size of esophageal varices (no varices, small and large varices). Results: Median ARFI score with interquartile range were 1.59 (1.33-1.99), 1.91 (1.45-2.16), 2.45 (2.07-2.98) in fibrosis stage 0 (n=54), fibrosis stage 1&2 (n=28), fibrosis stage 3 &4 (n=87) respectively. Mean ARFI values after excluding patients with acute hepatitis, ascites and BMI > 25 were 1.58± 0.36, 1.76±0.40, 2.50±0.59 in fibrosis stage 0 (n=25), fibrosis stage 1&2 (n=14), fibrosis stage 3 &4 (n=42) respectively. ARFI values were significantly higher in stage 3 & 4 fibrosis as compared to fibrosis grade 0 and 1&2 (p 0.001). APRI scores did not correlate with degree of fibrosis. ARFI values were significantly higher in patients with bilirubin > 10 mg/dl, ALT > 300 IU/L and ascites in fibrosis stage 0, 1&2. ARFI values were not affected in patients with high BMI. ARFI values of the liver did not correlate with presence and size of esophageal varices but splenic ARFI values could differentiate between presence and absence of varices. Conclusion: ARFI is reliable predictor of advanced fibrosis (stage 3&4) but cannot differentiate between stage 0 and early fibrosis. Splenic ARFI was useful in predicting presence of esophageal varices. ARFI values are not reliable in bilirubin >10 mg/dl, ALT > 300 IU/L and ascites.