A non-linear registration method for DCE-MRI and DCE-CT comparison in bladder tumors

The objective of this work is to examine the feasibility of a method to register dynamic contrast enhanced computed X-ray tomography (DCE-CT) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) datasets in order to make possible the comparison of parametric maps generated from tracer kinetic modeling. First, the CT and MR dynamic sets were matched temporally using a cross-correlation maximization approach. The registration was then performed through an affine transformation followed by a non-linear registration using free-form deformations (FFDs) based on B-splines. This was determined from the CT-MR pair that maximized Normalized Mutual Information (NMI). Then the ´extended Kety´ model was fitted to both CT and MR and K^trans, V_e and v_p parameters were obtained. The method was applied to 5 patients with bladder tumors. After registration, the overlap matching between CT and MR volume of interest (VOI) was on average 91%.