Citations

MRI guided focused ultrasound (FUS) has been shown to create thermal lesions where tissue stiffness changes significantly. To assess the correlation between tissue stiffness change and tissue ablation, a pilot animal based study was conducted to treat LNCaP tumors in vivo and Hep3B tumors immediately post mortem. MR elastography was used to analyze tissue stiffness before and after ablation. Treated tissue was excised immediately after each experiment and processed by routine histological analysis. Four prostate cancer tumors and four liver cancer tumors showed, on average, a threefold increase in stiffness due to FUS thermal treatment. Histology showed complete (100%) coagulation necrosis in these cases. These data suggest that MRE may be an effective means to assess tissue ablation.

A nuclear magnetic resonance imaging (MRI) method is presented for quantitatively mapping the physical response of a material to harmonic mechanical excitation. The resulting images allow calculation of regional mechanical properties. Measurements of shear modulus obtained with the MRI technique in gel materials correlate with independent measurements of static shear modulus. The results indicate that displacement patterns corresponding to cyclic displacements smaller than 200 nanometers can be measured. The findings suggest the feasibility of a medical imaging technique for delineating elasticity and other mechanical properties of tissue.