Measuring the Effect of Formalin Fixation on Ex Vivo Tissue Material Properties Using High Resolution 3D Quasi-Static MR Elastography at 7 Tesla for Improved Biomechanical Registration of Histopathology, and Correlation with the Effect of Fixation on T

Deirdre Maria McGrath¹, Warren D. Foltz¹, Kristy K. Brock^1,2

¹Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada; ²Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada

Correlation of 3D histopathology with in vivo images improves the understanding of disease representation in imaging. The pathology fixation process changes the material properties of tissue non-uniformly and if biomechanical registration is used, measures of these effects are required. A high resolution 3D quasi-static MR elastography (MRE) method at 7 T is presented for voxel-wise mapping of Youngs modulus across tissue volumes, and is applied to ex vivo canine prostate samples, pre- and post-fixation. The measures are validated using indentation testing. The effect of fixation on T1, T2 and ADC is also measured, to determine the relationship with material property changes.