High frequency liver surface ultrasound in evaluating post hepatitis C liver fibrosis in Yaounde

Adèle Tatiana ABO'O MELOM (tatianamelom@yahoo.fr)
Radiology, Faculty of Medicine and Biomedical Sciences, UYI
June, 2014


Introduction and objective: Hepatitis C virus (HCV) infection is one of the major causes of liver cirrhosis in Cameroon. Liver biopsy is currently considered as the “gold standard” for the diagnosis of cirrhosis. Its usage is limited by its invasive nature, the relative high cost and the risks it bears. More tolerated and better accepted non invasive tests have thus been developed, including the search of serological markers and liver stiffness measurement. However, these methods are expensive and not readily available in our country. Liver surface ultrasound (LSU) with high frequency probe appears to be a simple, accessible and reproducible test. In recent years, its interest in evaluating liver fibrosis or cirrhosis during chronic hepatitis is highlighted in the literature.

The aim of our study was to determine the diagnostic value of LSU in the diagnosis of severe fibrosis in a group of patients with chronic HCV infection in Yaoundé.

Methods: We carried out a cross sectional, descriptive and analytical study which took place from November 2013 to March 2014 in three health facilities in Yaoundé. We included patients aged at least 21 years, with positive antibodies anti HCV by ELISA test, HCV RNA positive by PCR, no prior HCV treatment, and in whom an evaluation of liver fibrosis by Fibrotest® was required. Patients with co-infection with human immunodeficiency virus or hepatitis B virus, a history of heart failure and/or cardiac arrhythmia, severe obesity and a pregnancy were excluded. For each patient, we collected clinical data (history of HCV infection, presence of comorbidities or previous complications, demographic and anthropometric data, search for clinical signs of cirrhosis) and biological data (Fibrotest®, HCV genotype, transaminases, serum albumin, prothrombin time and platelet count). Following an eight hours fasting period, liver ultrasound was performed using a 5-13 MHz linear probe for LSU and a 2-6 MHz convex probe for the other parameters. The ultrasound was performed at most 15 days after collection of blood samples for laboratory tests. Morphological parameters (left and right LSU, echogenicity of the liver parenchyma, liver size, maximum spleen length) and hemodynamic (portal vein diameter, portal flow velocity, hepatic vein waveform), among which some were grouped in a previously described score were specified. All examinations were performed by a single experienced radiologist who was
unaware of clinical and laboratory data. Ultrasound data of our patients were compared with those of 50 subjects with no hepatitis B and C viral markers.
Data were analysed using SPSS version 20.0, SPAD version 5.5 and STATA version 9.0 softwares. Univariate, bivariate, multivariate analysis and logistic regression were performed. The threshold P value was 0.05.

Results: We enrolled a total of 50 patients crossed to 50 controls. The average age of patients was 56 ± 11 years versus 49 ± 9 years for controls (P = 0.0007). The sex ratio was 2.3 for men in both groups. Comorbidities most frequently encountered were overweight (50%), alcohol consumption (34%) and high blood pressure (36%). The most frequent genotype was genotype 1 (42 %) followed by genotype 4 (36 %) and genotype 2 (22 %). We found severe fibrosis in 22% of our patients (Fibrotest® > 0.80). Thrombocytopenia was found in 30.4% of cases. Portal flow velocity, Left and right lobes LSU and ultrasound score were discriminating parameters between the two groups. We had a hepatomegaly in 22% of patients and 24% of controls. In bivariate analysis, the diagnosis of severe fibrosis was correlated with left lobe LSU (P = 0.003), maximum spleen length (P = 0.009), ultrasound score (P = 0.036) and liver size (P = 0.048). In multivariate analysis, left lobe LSU, ultrasound score, maximal spleen length and liver size were all associated in decreasing order with the diagnosis of severe liver fibrosis. The left lobe LSU showed a sensitivity of 81.8%, a specificity of 73%, a PPV of 47.4%, a NPV of 93.1% and an AUROC of 0.77 superior to that of the other parameters.

Conclusion: The left lobe LSU appears to be a reliable parameter for the diagnosis of severe fibrosis in patients with chronic HCV infection in our context. If these results are confirmed by further studies, left lobe LSU could limit the use of more expensive and demanding examinations such as Fibrotest® and liver biopsy. However, its reproducibility has to be assessed.