MR elastography shakes up assumptions about body MR

May 6, 2008 MR elastography shakes up assumptions about body MR James Brice -------------------------------------------------------------------------------- MR elastography debuted on Tuesday as a clinical application ready for diagnostic uses in the liver and many diagnostic niches elsewhere in the body. Modality inventor Dr. Richard Ehman noted during the morning plenary session that though elasticity is the physical property of tissue most changed by disease, it has never before been considered as a target for diagnostic imaging. Yet knowledge about the importance of tissue stiffness is as old as the ancient Greeks and the use of palpation.The propagation of mechanical waves through a region of interest can reveal the relative stiffness of anatomic structures. "The problem is that differences are seen in the realm of nanometers," Ehman noted. "Fortunately, MR is well suited for that role."A modified phase-contrast gradient-echo sequence was adapted for MRE. Elastograms are generated by an automated process yielding quantitative images of tissue stiffness based on a colorized linear scale calibrated into kiloPascals (kPa).Ehman described devices developed at Mayo and Charité Clinic in Berlin to induce mechanical shear waves through the abdomen for simultaneous interrogation with MR elastography. The MRE sequence takes about 15 seconds and can be performed at the end of a standard 45-minute MRI liver exam.Ehman listed 27 anatomic regions as potential candidates for MR elastography, including the spleen, pancreas, stomach, bowel, kidney, breast, and prostate. For the liver alone, Mayo researchers have identified 10 potential diagnostic applications: fibrosis, stenosis, portal hypertension, focal masses, diffuse masses, inflammatory disease, atrophy, metabolic conditions, pre-disease states, and response to therapyThough elastography is still considered experimental, Ehman and colleagues at the Mayo Clinic in Rochester, MN, have performed more than 500 studies on humans. "This is now the most common indication for abdominal MRI at the Mayo Clinic," he said.

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