Proceedings Article | 2 March 2011
Proc. SPIE. 7964, Medical Imaging 2011: Visualization, Image-Guided Procedures, and Modeling
KEYWORDS: Veins, Atrial fibrillation, Image segmentation, X-rays, Image registration, Fluoroscopy, X-ray imaging, Motion models, Motion estimation, 3D image processing
The treatment of atrial fibrillation has gained increasing importance in the field of
computer-aided interventions. State-of-the-art treatment involves the electrical isolation of the
pulmonary veins attached to the left atrium under fluoroscopic X-ray image guidance. Due to
the rather low soft-tissue contrast of X-ray fluoroscopy, the heart is difficult to see. To overcome
this problem, overlay images from pre-operative 3-D volumetric data can be used to add
anatomical detail. Unfortunately, these overlay images are static at the moment, i.e., they do not
move with respiratory and cardiac motion. The lack of motion compensation may impair X-ray
based catheter navigation, because the physician could potentially position catheters incorrectly.
To improve overlay-based catheter navigation, we present a novel two stage approach for respiratory
and cardiac motion compensation. First, a cascade of boosted classifiers is employed to
segment a commonly used circumferential mapping catheter which is firmly fixed at the ostium
of the pulmonary vein during ablation. Then, a 2-D/2-D model-based registration is applied to
track the segmented mapping catheter. Our novel hybrid approach was evaluated on 10 clinical
data sets consisting of 498 fluoroscopic monoplane frames. We obtained an average 2-D tracking
error of 0.61 mm, with a minimum error of 0.26 mm and a maximum error of 1.62 mm.
These results demonstrate that motion compensation using registration-based catheter tracking
is both feasible and accurate. Using this approach, we can only estimate in-plane motion. Fortunately,
compensating for this is often sufficient for EP procedures where the motion is governed
by breathing.
