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Techn. Fakultät Willkommen am Institut für Informatik FAU-Logo

Dipl.-Inf. Martin Koch

Alumnus of the Pattern Recognition Lab of the Friedrich-Alexander-Universität Erlangen-Nürnberg

Publications

A full list of my publications can be found here.

Towards Deformable Shape Modeling of the Left Atrium Using Non-Rigid Coherent Point Drift Registration
Bildverarbeitung für die Medizin 2013
Mesh models of the left atrium segmented from 3-D MRI volumes from four subjects (a-d). The colored spheres depict the anatomic position of the pulmonary vein

Martin Koch, Sebastian Bauer, Joachim Hornegger, Norbert Strobel

Modeling the deformable shape of the left atrium is of strong
interest for many applications in cardiac diagnosis and intervention. In
this paper, we propose a method for left atrium shape modeling using
non-rigid point cloud registration. In particular, we build upon the
concept of Coherent Point Drift (CPD) registration that considers the
alignment as a probability density estimation problem. Based on the set
of non-rigidly registered point clouds, we perform a principle component
analysis to establish a deformable shape model. In an experimental study
on ten clinical data sets, we evaluated the registration accuracy in terms
of average mesh-to-mesh distance, as well as on anatomical landmarks
on the left atrium. With the proposed method, we achieved registration
results with an average mesh-to-mesh error of 3:4mm. The average
landmark o set was 8:5mm.

Post-procedural evaluation of catheter contact force characteristics
SPIE Medical Imaging 2012: Computer-Aided Diagnosis, Vol. 8315, pp. 83152J, 2012
Color coded radio frequency ablation points. Landmark annotations, i.e. reconstructed pulmonary vein ostia or the coronary sinus, are used for orientation.

Martin Koch, Alexander Brost, Atilla Kiraly, Norbert Strobel, Joachim Hornegger 

Minimally invasive catheter ablation of electric foci, performed in electrophysiology labs, is an attractive treatment option for atrial fibrillation (AF) - in particular if drug therapy is no longer effective or tolerated. There are different strategies to eliminate the electric foci inducing the arrhythmia. Independent of the particular strategy, it is essential to place transmural lesions. The impact of catheter contact force on the generated lesion quality has been investigated recently, and first results are promising. There are different approaches to measure catheter-tissue contact. Besides traditional haptic feedback, there are new technologies either relying on catheter tip-to-tissue contact force or on local impedance measurements at the tip of the catheter. In this paper, we present a novel tool for post-procedural ablation point evaluation and visualization of contact force characteristics. Our method is based on localizing ablation points set during AF ablation procedures. The 3-D point positions are stored together with lesion specific catheter contact force (CF) values recorded during the ablation. The force records are mapped to the spatial 3-D positions, where the energy has been applied. The tracked positions of the ablation points can be further used to generate a 3-D mesh model of the left atrium (LA). Since our approach facilitates visualization of different force characteristics for post-procedural evaluation and verification, it has the potential to improve outcome by highlighting areas where lesion quality may be less than desired. 

Initiates file download(pdf)

Navigation System With Contact Force Assessment To Guide Pulmonary Vein Isolation Procedures
Society for Medical Innovation and Technology (SMIT), Tel Aviv, Israel, September 13-16, pp. 1-2, 2011
Visualization of contact force as Force-Time plot (lower left). Color coded threshold classifier for Force-Time Integral (FTI) (upper left).

Martin Koch, Arne Langenkamp, Atilla Kiraly, Alexander Brost, Norbert Strobel,
Joachim Hornegger

The common option for treatment of paroxysmal atrial fibrillation (AFib), once pharmacotherapy fails, is the electrically isolation of the pulmonary veins. Recent studies have emphasized the relevance of catheter tip-to-tissue contact
force for quality of ablation points. In these studies, the average contact force per patient was found to be correlated with the AFib recurrence rate. However, none of the previous studies explored if there is a relationship between the spatiotemporal force distribution and clinical outcome.
During electrophysiology (EP) procedures, visual guidance by either mapping systems and/or fluoroscopy systems is needed. Fluoroscopy enables the physician to get live images of the catheters during the procedure. Since softtissue resolution in X-ray images is very low, additional information, e.g., a model of the anatomical structure can be superimposed.

For each ablasion lesion created by the physician, force values are collected over time and stored as a vector. Each force vector can be evaluated individually. Due to the 3-D catheter localization feature of the augmented
fluoroscopy prototype, it is possible to associate the force vector with the 3-D location of the ablation lesion. The main advantages of the integrated system are live visualization of the catheter contact force on the fluoroscopy
images as well as extended evaluation possibilities about contact force applied during the procedure. 

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