Rigid & elastic composite registration of 3D LEG T1-weighted MR images for strain analysis

Abstract

Strain analysis of deformation eld is a crucial step for scienti c analysis of muscle structures in MRI data sets. They are commonly used for di erent types of data analysis such as force transmission among muscles which is one of the popular topics in recent years. Especially there is a popular trend of research concentrating on force transmission among lower leg. For successfully carrying out these types of tasks, a correct and e ective deformation eld of the MRI data must be obtained in order to get the expected corresponding strain assessments. These deformation elds are usually obtained by registration framework, in which two groups of data sets were registered to one another, one serving as moving data set, which is transformed to the other target, static data set. Formerly, in registration framework, the whole region of MRI, including bones, is elastically registered to each other. However, bone tissues are relatively hard comparing to those soft muscles, elastically registering these hard tissues, which yields non-zero deformation values among these regions, could negatively a ect the correctness of the obtained nal result. For that, we can think of keeping these bone regions as xed, and then elastically register the remaining parts to obtain a deformation eld in which there would be zero deformations in the bone regions. In this work, T1-weighted MR images of lower leg of human body in undeformed and deformed states are selected as test data. We rst segment the bone regions, keep them as xed, then perform elastic registration on the remaining parts on MR images of lower legs, and compare the obtained strain analysis of deformation eld results with those from unconstrained elastic registration method. We expect to see the nal result would be better than the one obtained by unconstrained elastic registration.