2D–3D registration of cardiac images using catheter constraints

Cardiac catheterization procedures are routinely guided by X-ray fluoroscopy but suffer from poor soft-tissue contrast and a lack of depth information. These procedures often employ pre-operative magnetic resonance or computed tomography imaging for treatment planning due to their excellent soft-tissue contrast and 3D imaging capabilities. We developed a 2D-3D image registration method to consolidate the advantages of both modalities by overlaying the 3D images onto the fluoroscopy by using catheters that are placed in vessels of the heart where they remain throughout the procedure. To achieve registration, an automatic global-fit algorithm was developed which minimized the root-mean-square distance error of the catheter to the medial line of its respective vessel. Data were processed for three clinical cases and an accurate registration was validated by visual inspection.