MR elastography.

Magnetic resonance (MR) elastography is an emerging method for measuring the viscoelastic properties of tissues. Hepatic fibrosis, which increases the elasticity or stiffness of the liver, can be detected and staged by MR elastography. The technique has several advantages compared with transient ultrasound elastography (FibroScan): it can evaluate much larger liver volumes; it can be performed in obese patients and in those with ascites; and it can assess the full three-dimensional displacement vector, allowing a more precise analysis of viscoelastic parameters. These technical advantages mean that MR elastography is more accurate forstaging liver fibrosis than is transient ultrasound elastography. Moreover, it has been shown in animal studies using MR elastography that parameters other than fibrosis can also increase liver elasticity, including inflammation and myofibroblast activation before extracellular matrix deposition. Because of its greater accuracy-but also its higher cost-MR elastography will probably have a complementary role alongside ultrasound elastography. Nevertheless, this role should be further studied, especially in terms of response to treatment and the early detection of chronic liver diseases such as steatohepatitis.