March 16, 2014

Computed tomography findings in liver fibrosis and cirrhosis

19 February 2014, doi:10.4414/smw.2014.13923
Cite this as: Swiss Med Wkly. 2014;144:w13923

Huber Adriana, Ebner Lukasa, Montani Matteob, Semmo Nasserc, Roy Choudhury Kingshukd, Heverhagen Johannesa, Christe Andreasa

a Institute of Radiology, University Hospital Inselspital, Bern, Switzerland
b Institute of Pathology, University of Bern, Switzerland
c Institute of Hepatology, University Hospital Inselspital, Bern, Switzerland
d Statistics Department, University College Cork, Ireland

Summary

PRINCIPLES: Computed tomography (CT) is inferior to the fibroscan and laboratory testing in the noninvasive diagnosis of liver fibrosis. On the other hand, CT is a frequently used diagnostic tool in modern medicine. The auxiliary finding of clinically occult liver fibrosis in CT scans could result in an earlier diagnosis. The aim of this study was to analyse quantifiable direct signs of liver remodelling in CT scans to depict liver fibrosis in a precirrhotic stage.

METHODS: Retrospective review of 148 abdominal CT scans (80 liver cirrhosis, 35 precirrhotic fibrosis and 33 control patients). Fibrosis and cirrhosis were histologically proven. The diameters of the three main hepatic veins were measured 1–2 cm before their aperture into the inferior caval vein. The width of the caudate and the right hepatic lobe were divided, and measured horizontally at the level of the first bifurcation of the right portal vein in axial planes (caudate-right-lobe ratio). A combination of both (sum of liver vein diameters divided by the caudate-right lobe ratio) was defined as the ld/crl ratio. These metrics were analysed for the detection of liver fibrosis and cirrhosis.

RESULTS: An ld/crl-r <24 showed a sensitivity of 83% and a specificity of 76% for precirrhotic liver fibrosis. Liver cirrhosis could be detected with a sensitivity of 88% and a specificity of 82% if ld/crl-r <20.

CONCLUSION: An ld/crl-r <24 justifies laboratory testing and a fibroscan. This could bring forward the diagnosis and patients would profit from early treatment in a potentially reversible stage of disease.

Key words: liver fibrosis and cirrhosis; abdominal computed tomography; hepatic vein diameter; caudate right lobe ratio

Introduction

Liver cirrhosis is the final consequence of all chronic liver diseases [1]. Most common causes are alcoholic fatty liver disease (AFLD), nonalcoholic fatty liver disease (NAFLD) and viral hepatitis [2, 3]. Chronic inflammation leads to potentially reversible liver fibrosis and ends in irreversible cirrhosis with cross-linked collagen and regenerative nodules [4]. Early diagnosis improves the benefit of therapeutic strategies before the development of irreversible and potentially lethal complications such as loss of liver function, oesophageal variceal bleeding, hepatic encephalopathy and hepatocellular carcinoma [5, 6].

The noninvasive diagnosis of liver fibrosis and cirrhosis is built on laboratory testing and the well-established fibroscan [7]. Recently, new sensitive methods using magnetic resonance imaging (MRI) have been described, such as MR-elastography [8], double contrast-enhanced MRI [9] and diffusion weighted MRI [10]). Computed tomography (CT) is useful for imaging liver cirrhosis complications, such as portosystemic collaterals with bleeding or hepatocellular carcinoma (HCC). However, this is not an appropriate method for the primary diagnosis of liver fibrosis, because of the radiation dose and inferior accuracy compared to the fibroscan. On the other hand, clinically occult liver fibrosis as an auxiliary finding in routine abdominal CT scans is underdiagnosed. Even liver cirrhosis has a mediocre sensitivity (77.1%–84.3%) and specificity (52.9%–67.6%) in CT [11]. However, since CT is an important and frequently used diagnostic tool in modern medicine, an accurate method to detect liver fibrosis in CT scans could bring forward the diagnosis and enable treatment in an early stage of fibrosis before its clinical appearance.

We hypothesise that indirect findings of liver remodelling occur rather late when chronic portal hypertension has already been established (e.g. splenomegaly, gastrointestinal wall thickening, portosystemic collaterals, recanalisation of the umbilical vein and ascites [1214]).

Qualitative direct signs of liver remodelling (atrophy of the right liver lobe with a notch between right and caudate lobe, heterogeneity of liver parenchyma, nodular surface, blunt liver edge and enlarged gall bladder fossa [1214]) are limited parameters as a result of subjective reader impression and experience.

Thus, we propose the use of quantifiable direct signs of hepatic remodelling which are assessable in axial planes without the need for time-consuming image reconstructions.

There are two interesting metrics for direct liver remodelling: the caudate-right lobe ratio (crl-r) [18], which describes the width of the caudate lobe in proportion to the width of the right hepatic lobe, and measurement of the hepatic vein diameters [19]. We hypothesise that these metrics correlate with early liver fibrosis in a precirrhotic stage and can be used as quantifiable markers to depict liver fibrosis in abdominal CT scans. An analysis of these metrics alone and in combination for the detection of liver fibrosis was performed, as was a comparison with other qualitative and quantitative imaging findings.

Patients and methods

Patient population:

A total of 148 patients (108 male/40 female) were retrospectively included between January 2009 and March 2012 at our hospital, including 80 patients with histologically proven liver cirrhosis (fibrosis stage 4), 35 with histologically proven precirrhotic liver fibrosis stage 1–3 and a control group of 33 trauma patients without known liver pathology. The mean age of all selected patients was 57.3 years (range: 32–75 years). Informed consent was not required owing to the retrospective nature of this study.

The 80 patients (59 male/21 female) with liver cirrhosis (29 Child A, 31 Child B, 30 Child C) and the 35 patients with precirrhotic stage of liver fibrosis (6 fibrosis grade 1, 10 fibrosis grade 2 and 19 fibrosis grade 3) were included if they had undergone a CT scan with portal venous phase in the radiological information system (Centricity RISi 4.1, GE Healthcare) of our hospital. Liver fibrosis and cirrhosis was histologically proven by intercostal percutaneous biopsy from the right liver lobe with the “Menghini-technique” with pre- and post-procedural sonographic checks. Patients who had undergone an earlier partial liver resection or liver transplantation or those who had a transjugular portosystemic shunt (TIPS) were excluded.

Reasons for the abdominal CT scans were as follows (cirrhosis group/precirrhotic fibrosis group): HCC (40/18), tumour other than HCC (9/6), portal vein thrombosis (8/0), abscess (6/4), bleeding (7/0), acute abdomen (4/2), pancreatitis (3/3), trauma (2/1), abdominal hernia (1/0) and portal vein thrombosis (0/1).

The control group consisted of 33 consecutively selected trauma patients (23 male/10 female) with a mean age of 58.4 years (range: 51–70 years) who were examined with a portal venous phase abdominal CT scan. Patients with liver laceration, known liver fibrosis or cancer, and patients receiving potentially hepatotoxic medication were excluded. A summary of the patient population is shown in figure 1.

SMW-13923-Fig-01

Figure 1 Patient population. Abdominal computed tomography scans of 148 patients were retrospectively analysed. Included were 80 patients with liver cirrhosis, 35 patients with earlier liver fibrosis and 33 control patients without known liver disease.

The clinical records of all patients in the fibrosis/cirrhosis group were surveyed. The aetiology of fibrosis was as follows: AFLD in 42 patients (37%), viral hepatitis in 45 patients (39%), NAFLD in 11 patients (10%), haemochromatosis in 5 patients (4%) and alpha-1–antitrypsin deficiency (A1AD) in 2 patients (2%). Aetiology of the fibrosis was unknown in 10 patients (9%).

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