Visualizing tissue compliance with MR imaging

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Abstract
We propose a method for visualizing the mechanical properties of tissue based on the use of periodic mechanical compression in conjunction with phase-contrast MR imaging. A specialized mechanical transducer was used to provide programmable compression pulses to the surface of compliant phantoms. These compression pulses were synchronized to a spin-echo sequence with motion-sensitizing gradients to generate phase information reflecting spin displacement throughout the phantom. This sequence was tested with two agarose gel phantoms. The first was a cylinder containing three parallel layers of varying compliance and the second was composed of a semirigid sphere suspended in a uniform layer of decreased elastic modulus. Images showed complex patterns of motion throughout the phantom, which correlated with expected motion behavior of the phantom structures. This indicates that the biomechanical properties of tissues may be elucidated through the use of motion-sensitized MR imaging and suggests that a form of image contrast relating to tissue elasticity may be feasible.