ARFI elastography in patients with chronic autoimmune liver diseases: A preliminary study
Introduction
The prognosis and management of chronic liver diseases depends largely on the extent and progression of hepatic fibrosis, which involves replacement of the hepatic parenchyma by extracellular matrix [1]. Liver biopsy is considered the gold standard method for assessing hepatic fibrosis because it is a direct method [2]. The main limitation of this procedure is its invasiveness, which in rare cases can lead to both minor and major complications [2], [3], [4]. Abdominal pain is associated with the procedure in roughly 25% of all cases, and procedure-related complications that require hospitalization are reported in 1–3% [5], [6], [7].
Other limitations include the risk of sampling errors [8], [9], [10], [11] and operator-dependent variability in interpreting the results [12], which can result in under – as well as overestimation of the degree of liver fibrosis. In addition, the procedure is expensive, and it cannot be repeated frequently to monitor the evolution of the disease. There are also situations in which liver biopsy are contraindicated, including patients with coagulation disorders, those who uncooperative, and those who refuse to undergo biopsy.
Because of the limitations of liver biopsy and the dynamic nature and prognostic/therapeutic relevance of hepatic fibrogenesis in patients with chronic liver disease, several simple noninvasive methods have been proposed over the last decade to obtain simple, low-cost estimates of the extent of this process, which are also accurate, repeatable, and reproducible. These methods have been widely evaluated in patients with viral liver disease caused by hepatitis virus B or C and in those with nonalcoholic fatty liver disease (NAFLD), but there is much less information on their use in rarer forms of chronic autoimmune liver disease, such as primary biliary cirrhosis (PBC), autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and the AIH-PBC overlap syndrome.
The new methods used to evaluate liver fibrosis include biologic tools based on the use of direct and indirect biohumoral markers and instrumental methods. Among biologic tools, those that have been most widely tested are the Fibrotest and the APRI score (AST to platelet ratio index). Instrumental approaches include impulse-based elastography (FibroScan) and ultrasound-based elastography (acoustic radiation force impulse elastography – ARFI – and real-time elastography).
The FibroScan has been proposed for assessment of liver stiffness as an indirect index of hepatic fibrosis. It is based on the use of mechanical waves generated by vibrations. The diagnostic performance of this method in patients with HCV-related liver disease has been evaluated in three important multicenter studies [13], [14], [15], and it has also been tested in patients with NAFLD [16]. Data on its use in patients with autoimmune liver disease are not as clear or concordant [17], [18].
A more recently developed approach, ultrasound-based elastography, is a technique used with conventional B-mode sonography to evaluate the elastic properties of tissues. It has been employed mainly for the differentiation of malignant and benign thyroid, breast, and prostate lesions and for characterization of atherosclerotic plaques [19], [20], [21], [22], [23].
Recent studies have evaluated its use in the study of hepatic fibrosis in patients with chronic liver disease (viral in most cases), and the results have shown good concordance with histological data [24], [25]. Takahashi et al., for example, found that liver stiffness measured with ARFI correlates with Metavir scores of liver fibrosis. Again, however, there are fewer data on the less common autoimmune liver diseases.
The main objective of this study was to determine patients with chronic autoimmune liver disease can be distinguished from normal subjects with comparative analysis of ARFI elastographic findings in the right and left lobes of the liver.
Section snippets
Materials and methods
The study population included male and female patients with chronic autoimmune liver disease who underwent liver biopsy in the Dept. of Digestive Tract Diseases and Internal Medicine of Saint Orsola-Malpighi Policlinic in Bologna, Italy. The criteria for enrollment were: a) age ≥ 18 years; b) diagnosis of one of the following diseases: PBC, AIH, PSC, or an overlap syndrome; c) indications for liver biopsy; d) patient consent to participation in the study. The diagnosis of PBC was based on the
Results
On the basis of the histological findings, the fibrosis was classified as follows: F0: 0 patients; F1: 4 patients; F2: 4 patients; F3: 1 patient; F4: 0 patients. The SWV in the patient group (right lobe: 1.51 ± 0.44; left lobe: 1.57 ± 0.40) was significantly higher than that of controls (right lobe: 1.08 ± 0.10 [P = 0.002]; left lobe: 1.12 ± 0.13 [P = 0.013]). The SWVs of the right and left lobes were not significantly different from one another in the patient group (P = 0.779) or in the
Discussion
In recent years various methods have been proposed for the evaluation of liver fibrosis with the aim of reducing the risk (already quite low) associated with liver biopsy, including ultrasound-based elastography. Our preliminary study demonstrates that ARFI elastography can reliably differentiate healthy subjects from patients with liver fibrosis related to chronic liver disease. The SWV values in the patient group were significantly higher than those of the healthy controls. Therefore, ARFI
Conflict of interest
The authors have no conflict of interest to disclose.
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