MAGNETIC-RESONANCE-IMAGING TECHNIQUES FOR DETECTION OF ELASTICITY VARIATION

The relative success of manual palpation in the detection of breast ca ncer would suggest that a method for remote palpation resulting in a m easurement of tissue elasticity could provide a diagnostic tool for de tecting cancerous lesions deeper within the breast. This presumption i s based in part on the excellent contrast between neoplastic and norma l tissue due to the large (orders of magnitude) relative variation in the shear elastic modulus. By comparison, the bulk deformational modul us maintains the same value to within 20% for most soft tissues. A spe cific method of magnetic-resonance imaging (MRI) which measures tissue displacements has been used in experiments with a phantom containing regions of increased Young's modulus as a demonstration. The spatial m odulation of magnetization technique uses the displacement of a spatia l grid pattern caused by spin saturation to track regional motion. Mat hematical reconstruction of the distribution of elastic moduli is show n for select examples. Any modality, e.g., MRI, ultrasound, etc., whic h can detect local tissue motion with sufficient spatial resolution ca n be used and therefore the results presented here should give an indi cation of the utility of such motion tracking techniques to future mea surement of tissue elasticity.