Accuracy and reliability of microbubble ultrasound measurements for the non-invasive assessment of hepatic fibrosis in chronic hepatitis C.

Aim:   Contrast-enhanced ultrasound can be used to assess liver disease severity non-invasively by observing intra- and extrahepatic hemodynamic changes. Transit times are calculated to include intra- and extrahepatic components (hepatic vein transit time, HVTT) or the intrahepatic component (hepatic transit time, HTT), but these have not been compared directly. We aimed to compare diagnostic accuracy of HVTT and HTT in gauging the severity of chronic hepatitis C (CHC) and to assess inter- and intra-observer reliability.

Methods:   Recorded ultrasound scans performed on 75 patients with biopsy-staged CHC, using the microbubble contrast agent Sonovue were analyzed.

Results:   Diagnostic accuracy of HTT and HVTT for diagnosis of cirrhosis was 0.78 and 0.71 (P = 0.24). Diagnostic accuracy of HTT and HVTT for diagnosis of fibrosis stage >2 was 0.76 and 0.72 (P = 0.23). Negative predictive value for cirrhosis using this cut-off was high for both techniques (HVTT, 88%; HTT, 92%), suggesting utility for exclusion of cirrhosis. Inter-observer reliability for HTT and HVTT were 0.92 and 0.94, respectively. Intra-observer reliability for HTT and HVTT were 0.98 and 0.99.

Conclusion:   In this cohort, reliability exceeded 90% while diagnostic accuracy was in keeping with previous studies of microbubble transit time analysis. Despite higher numerical diagnostic accuracy for HTT, no significant difference was demonstrated between the techniques, suggesting that both methods can be used reliably.