Newer ultrasound and magnetic resonance (MR) imaging tests yield encouraging initial results in diagnosing fibrosis (scarring) and cirrhosis of the liver, according to three studies in the October issue of the journal Clinical Gastroenterology and Hepatology.
With further research, these and other non-invasive imaging techniques may reduce the need for biopsies—procedures done to obtain a tissue sample—to determine the presence and severity of fibrosis and cirrhosis.
Two of the three new papers evaluated techniques of elastography—tests that evaluate reactions to ultrasound vibrations or energy waves as a means of measuring the elasticity or stiffness of the liver tissue. Lower elasticity (or higher stiffness) corresponds to increased fibrosis or scarring. When fibrosis becomes severe, it signals the presence of cirrhosis.
Dr. Jayant A. Talwalkar and colleagues of Mayo Clinic College of Medicine, Rochester, Minn., analyzed the current evidence on ultrasound-based transient elastography—the approach that has received the most research attention to date. Based on data from 18 previous studies, the ultrasound test was highly accurate in identifying patients with cirrhosis, defined as severe (stage IV) fibrosis of the liver. About 90 percent of patients with cirrhosis were correctly identified by ultrasound-based transient elastography. The test was somewhat less accurate in detecting less-severe fibrosis.
Because the studies used differing cutoff points, the analysis could not establish the true accuracy of this emerging technology. The researchers highlight the need for additional high-quality studies including patients with liver fibrosis ranging from mild to severe.
Dr. Meng Yin and colleagues, also of Mayo Clinic College of Medicine, evaluated a different approach to measuring liver elasticity/stiffness: MR elastography. Although the principle is the same as with the ultrasound technique, MR elastography measures reactions to mechanical shear waves, rather than ultrasound vibrations.
The researchers performed MR elastography in 50 patients with chronic liver disease and 35 normal volunteers. The test was nearly 100 percent accurate in identifying patients with any degree of liver fibrosis, including those with mild fibrosis. With further study, Dr. Yin and colleagues believe MR elastography could be a useful initial test for fibrosis—avoiding the discomfort and risks of liver biopsy for many patients, while potentially increasing the reliability of diagnosis.
Dr. Chen-Hua Liu and colleagues of National Taiwan University Hospital, Taipei, evaluated a different ultrasound technique for measuring fibrosis. Using widely available duplex Doppler ultrasound equipment, they measured the characteristics of blood flow in the vessels in and around the liver in patients with chronic hepatitis C—an increasingly important cause of fibrosis and cirrhosis.