Focus areas

Many disease processes cause large changes in the mechanical properties of previously healthy tissue. Malignant tumors are often much harder to touch than surrounding tissues. This accounts for the efficacy of palpation as a clinical technique to detect cancer and other abnormalities.

Many tumors of the thyroid, breast and prostate are still first detected by this centuries-old diagnostic technique. But this technique has drawbacks:

• Palpation is a subjective technique.
• Small abnormalities and those areas inaccessible to a physician can't be detected by touch.
• Conventional imaging methods, such as ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI), do not provide information that is analogous to palpation.

The research goal of Dr. Ehman's lab is to develop, validate, explore and identify high-impact applications of a new MRI-based diagnostic imaging technology to quantitatively assess the mechanical properties of tissues. This technique is called magnetic resonance elastography (MRE).

With MRE, mechanical waves are generated in tissue, and a remarkably sensitive phase-contrast MRI technique using synchronous motion-sensitizing gradients images the pattern of wave propagation. Specially developed mathematical algorithms are used to analyze the wave images and generate quantitative images depicting the stiffness and other mechanical properties of tissue.

MRE is a useful imaging tool that can:

• Noninvasively palpate by imaging regions of the body that are beyond the reach of the physician's hand.
• Delineate tumors and other abnormalities before they are severe enough to detect by touch.
• Provide greater sensitivity to assess changes in tissue mechanical properties.
• Provide useful new quantitative imaging biomarkers to characterize tissue properties.