Liver, Pancreas and Biliary TractThe role of bright liver echo pattern on ultrasound B-mode examination in the diagnosis of liver steatosis
Introduction
Liver steatosis defined as fat accumulation within hepatocytes may represent the only histologically detected alteration of a group of metabolic liver disorders, ranging from simple fat accumulation to chronic hepatitis and/or cirrhosis, known as nonalcoholic fatty liver diseases (NAFLDs). Over the last few years, studies attempting to evaluate the role of steatosis in hepatitis C virus (HCV) demonstrated that steatosis itself could determine progression of liver disease in chronic HCV hepatitis [1], [2], [3]. Recent papers have also shown steatosis as a relevant cofactor of liver damage [4], [5]. Moreover, the high prevalence of steatosis in HCV-related chronic hepatitis has been documented [6] and, in particular, its association with genotype 3a of the C virus [7] and its reduction in genotype 3a patients who had a sustained virological response after treatment [7].
The role of B-mode ultrasonography in the diagnosis and management of patients affected by chronic liver disease continues to grow, although its clinical relevance is still debated [8]. In particular, the ability of ultrasound to evaluate the presence and degree of hepatic steatosis remains uncertain [9], [10]. Several studies have shown that a bright liver echo pattern (BLEP) seen on B-mode ultrasonography correlated highly with a diagnosis of hepatic steatosis. Nevertheless, the interference of liver fibrosis is still under debate, and might lower the specificity and sensitivity of BLEP [11], [12], although data supporting this argument are weak [10], [11]. However, the introduction of other ultrasound features, such as posterior beam attenuation, has increased the sensitivity of echography to hepatic steatosis [11], [13]. Previous data by Garra et al. [13] and Taylor et al. [14] demonstrated that particular ultrasound parameters of steatosis were solely associated with fat accumulation in the hepatocytes. Yet, these findings have not been validated in consecutive clinical series of patients with HCV infection, which might be of scientific relevance, given the association between HCV infection and liver steatosis [1], [2], [3].
We conducted a study to determine the correlation between BLEP on B-mode ultrasonography and the presence of steatosis and/or fibrosis in a group of consecutive patients who were given an initial diagnosis of chronic liver disease of various aetiologies.
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Patients and methods
This is a prospective study which started on January 2001 and ended on December 2003. We enrolled 235 patients (median age 52, range 17–72; M/F 127/88) consecutively admitted to our institution for suspicion of chronic liver disease of various aetiologies. None of these patients demonstrated any clinical or biochemical signs of cirrhosis (i.e., all had a platelet count of >140,000 × 109/L; spleen diameter <14 cm; normal portal, splenic and mesenteric vein diameters [respectively: 12 mm, 9 mm, 9 mm]),
Statistical analysis
Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) tests were calculated when appropriate. Univariate analysis (logistic linear regression) was used for correlations.
Results
The epidemiologic characteristics of the 235 patients are indicated in Table 1. Nineteen patients were excluded from the statistical analysis because their biopsy specimens were of insufficient size (n = 11) or because it was not possible to evaluate all of the echographic parameters (n = 8).
The estimated interobserver variabilities for the single echographic parameters evaluated were as follows: liver echo pattern, K = .83; areas with different patterns of fat infiltration, K = .76; and posterior beam
Discussion
Ultrasound is widely used in the diagnosis of patients with suspected liver disease because it is highly accurate, relatively inexpensive and noninvasive. Yet, despite the remarkable technologic improvement in ultrasound equipment during the last decade, the role of ultrasound in the diagnosis and staging of chronic liver disease is still a subject of debate, with few studies appearing in the recent literature [18], Limitations of this technique might be represented by the fact that the
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