Quantitative imaging of liver fat and fibrosis

As demonstrated in this thesis, accurate non-invasive imaging techniques exist that can be used for the evaluation of liver fibrosis and steatosis, each with their own advantages and disadvantages. When looking at steatosis, ultrasound is cheap and widely available. Disadvantages are its qualitative nature and interobserver variability. Compared to other available techniques, the diagnostic accuracy of ultrasonography for steatosis evaluation is relatively low for mild and moderate steatosis. Computed tomography (CT) can quantify the amount of steatosis, however the main drawback of CT is the ionizing radiation. Like ultrasonography, the accuracy of CT for mild steatosis is limited. Magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (1H-MRS) have a high accuracy for measuring steatosis over its entire range. Drawbacks however included costs and availability. For detection and staging of fibrosis, transient elastography (TE) and magnetic resonance elastography (MRE) have been studied and discussed. TE is a rapid procedure with low intra- and interobserver variability. Drawbacks include the one-dimensionality of the measurement (no image of the liver available), and failure in obese patients and in patients with ascites. MRE overcomes these limitations, and evaluates a much larger portion of the liver. However, due to attractive alternatives with comparable accuracy, MRE may not become the first-line examination to screen for liver fibrosis