Electrophysiology (EP) studies and catheter ablation have become important treatment options for several types of cardiac arrhythmias. We present a novel image-based approach for automatic detection and 3-D reconstruction of EP catheters where the physician marks the catheter to be reconstructed by a single click in each image. The result can be used to provide 3-D information for enhanced navigation throughout EP procedures. Our approach involves two X-ray projections acquired from different angles, and it is based on two steps: First, we detect the catheter in each view after manual initialization using a graph-search method. Then, the detection results are used to reconstruct a full 3-D model of the catheter based on automatically determined point pairs for triangulation. An evaluation on 176 different clinical fluoroscopic images yielded a detection rate of 83.4%. For measuring the error, we used the coupling distance which is a more accurate quality measure than the average point-wise distance to a reference. For successful outcomes, the 2-D detection error was   $1.7\ {\rm mm} \pm 1.2$    mm. Using successfully detected catheters for reconstruction, we obtained a reconstruction error of   $1.8\ {\rm mm} \pm 1.1$    mm on phantom data. On clinical data, our method yielded a reconstruction error of   $2.2\ {\rm mm} \pm 2.2$   mm.
['Matthias Hoffmann', 'Alexander Brost', 'Martin Koch', 'Felix Bourier', 'Andreas K. Maier', 'Klaus Kurzidim', 'Norbert Strobel', 'Joachim Hornegger']
Electrophysiology Catheter Detection and Reconstruction From Two Views in Fluoroscopic Images