A framework for CT and MR image fusion in cardiac resynchronization therapy

A framework for computed tomography (CT) and magnetic resonance (MR) image fusion is proposed for potential application in cardiac resynchronization therapy (CRT). The MR dataset has been pre-processed compensating for organ motion induced inter-slices misalignment. The geometrical center alignment of CT and MR short axis (SAX) reconstructed 3D volume has been considered as initialization for voxel-based 6 degree of freedom image registration between 3D CT (moving image) and MR SAX (fixed image). The process driven by normalized mutual information cost function featuring multi-resolution two-level approach with gradient descent optimizer was adopted to improve the numerical stability. The retrieved transformation was applied to CT to perform data fusion with LAX and Gd-enhanced MR images. Fused data was visually inspected and judged reliable for correspondence of cardiac structures. The proposed approach constitutes the pre-processing step for multi-modality visualization of different information: coronary veins anatomy from CT, necrotic tissue from Gd-enhanced MR, dyssynchrony map from SAX and LAX MR.