Elastic material model mismatch effects in deformable motion estimation

Deformable motion models are useful for analysis of dynamic datasets exhibi ting non-rigid motion, as in gated cardiac PET. We employ an algorithm that obtains a vector field to describe the relative motion of each voxel betwe en two data sets. The estimation is based on a two-component cost function: an image matching component, and a motion field smoothness component. An i mportant aspect of obtaining an accurate motion field estimate is properly balancing the weight between the two cost components. We show that by using a material elastic model inspired by continuum mechanics, an intuitive int erpretation of the weighting factors for the smoothness constraint may be o btained. Further, we show that mismatches between actual material elastic p arameters and those used by the estimation algorithm can lead to greater es timation error. Results are validated using an ellipsoidal phantom simulati ng compressible and incompressible deformations.