MRI Techniques Provides Better Evaluation of Liver Fibrosis

Magnetic resonance imaging (MRI) imagery is emerging as a non-invasive way to determine the existence and extent of hepatic fibrosis. It could ultimately help the development of pharmacologic strategies to treat the condition.

Currently, the best method to evaluate hepatic fibrosis is liver biopsy; however, it is an invasive procedure that can cause serious side effects. Researchers have been assessing less invasive techniques such as blood tests, and imaging strategies such as ultrasound, but up to now, they have not proven sensitive enough to detect the various stages of fibrosis.

Over the past decade, a number of technologic advances have been made in MRI of the liver. Researchers led by Dr. Jayant Talwalkar, from the Mayo Clinic (Rochester, MN, USA), examined the current state of MR imaging and the studies that looked at its utility in detecting liver fibrosis. They discovered that contrast-enhanced MRI, MR spectroscopy, and diffusion-weighted MRI have shown promise for detecting hepatic fibrosis, although they require further modifications.

However, the technology that is showing the greatest promise is MR elastography, which quantitatively assesses tissue stiffness. Recent studies have shown that MR elastography has high sensitivity and specificity in detecting fibrosis stages. "As with other techniques, efforts to standardize the equipment and techniques used for MR elastography should be pursued to maximize diagnostic accuracy and facilitate comparison of results in different settings,” the authors suggested. "Reproducibility appears good from initial studies but requires additional study for verification.”

The investigators emphasized that the design and conduct of high-quality diagnostic accuracy studies are vital for ongoing validation of these emerging non-invasive techniques for determining hepatic fibrosis. Most relevant studies to date have included small numbers of patients and lacked independent assessment, issues that should be addressed in future studies.

Once MRI techniques have become suitably refined, patients will likely prefer them to liver biopsy. While the number of patients screened for hepatic fibrosis may increase using MR imaging, proof will be required that early detection and intervention can reduce morbidity and resource utilization associated with the clinical sequelae of advanced disease, the authors pointed out.

"The development of a reliable and valid non-invasive method to assess hepatic fibrosis could result in comparable or, perhaps, improved accuracy in terms of staging,” the researchers concluded. "The emergence of MR imaging techniques [singly or in combination with other methods] could result in the performance of true functional hepatic imaging.”

The study was published in the January 2008 issue of the journal Hepatology.


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