Elasticity reconstruction from experimental MR displacement data: initial experience with an overlapping subzone finite element inversion process

The determination of the elastic property distribution in heterogeneous gel samples with a finite element based reconstruction scheme is considered. T he algorithm operates on small overlapping subzones of the total field to a llow for a high degree of spatial discretization while maintaining computat ional tractability. By including a Maxwellian-type viscoelastic property in the model physics and optimizing the spatial distribution of this property in the same manner as elasticity, a Young's modulus image is obtained whic h reasonably reflects the true distribution within the gel. However, the im age lacks the clarity and accuracy expected based on simulation experience. Preliminary investigations suggest that transient effects in the data are the cause of a significant mismatch between the inversion model, which assu mes steady-state conditions, and the actual displacements as measured by a phase contrast MR technique. (C) 2000 American Association of Physicists in medicine.