Norbert Rahn

Automatic left atrium segmentation by cutting the blood pool at narrowings

This paper presents a method to extract heart structures from CTA and MRA data sets, in particular the left atrium. First, the segmented blood pool is subdivided at narrowings in small components. Second, these basic components are merged automatically so that they represent the different heart structures. The resulting cutting surfaces have a relatively small diameter compared to the diameter of the neighboring heart chambers. Both steps are controlled by only one fixed parameter. The method is fast and allows interactive post-processing by the user. Experiments on various data sets show the accuracy, robustness and repeatability of this approach.

Registration of high-resolution 3D atrial images with electroanatomical cardiac mapping: evaluation of registration methodology

Registration of atrial high-resolution CT and MR images with a cardiac mapping system can provide real-time electrical activation information, catheter tracking, and recording of lesion position. The cardiac mapping and navigation system comprises a miniature passive magnetic field sensor, an external ultralow magnetic field emitter (location pad), and a processing unit (CARTO, BiosenseWebster). We developed a progressive methodology for both interactively and automatically registering high-resolution 3D atrial images (MR or CT) with the corresponding electrophysiological (EP) points of 3D electro-anatomical (EA) maps. This methodology consists of four types of registration algorithms ranging from landmark-based to surface-based registration. We evaluated the methodology through phantom and patient studies. In the phantom study, we obtain a CT scan of a transparent heart phantom, and then use the CARTO system to visually pick a number of points inside the transparent phantom. After segmenting the atrium into a 3D surface, we register it to the measured EA map. The results are compared to the manual EA point measurements. In the 13-patient study, the four types of registrations are evaluated: visual alignment, landmark registration (three EA points are used), surface-based registration (all EA points are used), and local surface-based registration (a subset of the EA points is used, and one specific point is given a higher weight for a better “local registration”). Surface-based registration proves to be clearly superior to visual alignment. This new registration methodology may help in creating a novel and more visually interactive workflow for EP procedures, with more accurate EA map acquisitions. This may improve the ablation accuracy in atrial fibrillation (AFib) procedures, decrease the dependency on fluoroscopy, and also lead to less radiation delivered to the patient.

Ein neuer Visualisierungsansatz zur überlagerten Darstellung registrierter Bildserien

Dieser Beitrag stellt einen neuen Visualisierungsansatz zur uberlagerten Darstellung registrierter Bildserien vor. Mit dem neuen Ansatz konnen Probleme des herkommlichen α-Blendings vermieden werden, indem beliebig viele Grauwert-Teilbereiche beider registrierter Bildserien mit unterschiedlichen Gewichtungen geblendet werden. Die Identifikation von zu blendenden Grauwert-Teilbereichen beider Original-Bildserien erfolgt dabei mit Hilfe einer intuitiven graphischen Benutzeroberflache. Die Vorteile des Visualisierungsansatzes werden anhand von fusionierten funktionellen und morphologischen klinischen SD-Bildserien aufgezeigt.