TY - CHAP A1 - Brost, Alexander A1 - Wu, Wen A1 - Koch, Martin A1 - Wimmer, Martin A1 - Chen, Terrence A1 - Liao, Rui A1 - Hornegger, Joachim A1 - Strobel, Norbert T1 - Combined Cardiac and Respiratory Motion Compensation for Atrial Fibrillation Ablation Procedures T2 - Medical Image Computing and Computer-Assisted Intervention N2 - Catheter ablation of atrial fibrillation has become an accepted treatment option if a patient no longer responds to or tolerates drug therapy. A main goal is the electrical isolation of the pulmonary veins attached to the left atrium. Catheter ablation may be performed under fluoroscopic image guidance. Due to the rather low soft-tissue contrast of X-ray imaging, the heart is not visible in these images. To overcome this problem, overlay images from pre-operative 3-D volumetric data can be used to add anatomical detail. Unfortunately, this overlay is compromised by respiratory and cardiac motion. In the past, two methods have been proposed to perform motion compensation. The first approach involves tracking of a circumferential mapping catheter placed at an ostium of a pulmonary vein. The second method relies on a motion estimate obtained by localizing an electrode of the coronary sinus (CS) catheter. We propose a new motion compensation scheme which combines these two methods. The effectiveness of the proposed method is verified using 19 real clinical data sets. The motion in the fluoroscopic images was estimated with an overall average error of 0.55 mm by tracking the circumferential mapping catheter. By applying an algorithm involving both the CS catheter and the circumferential mapping catheter, we were able to detect motion of the mapping catheter from one pulmonary vein to another with a false positive rate of 5.8 %. T3 - Lecture Notes in Computer Science - 6891 Y1 - 2011 SN - 978-3-642-23622-8 SN - 978-3-642-23623-5 U6 - https://doi.org/10.1007/978-3-642-23623-5_68 VL - 14 SP - 540 EP - 547 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Brost, Alexander A1 - Liao, Rui A1 - Strobel, Norbert A1 - Hornegger, Joachim T1 - Respiratory motion compensation by model-based catheter tracking during EP procedures JF - Medical Image Analysis N2 - In many cases, radio-frequency catheter ablation of the pulmonary veins attached to the left atrium still involves fluoroscopic image guidance. Two-dimensional X-ray navigation may also take advantage of overlay images derived from static pre-operative 3D volumetric data to add anatomical details otherwise not visible under X-ray. Unfortunately, respiratory motion may impair the utility of static overlay images for catheter navigation. We developed a novel approach for image-based 3D motion estimation and compensation as a solution to this problem. It is based on 3D catheter tracking which, in turn, relies on 2D/3D registration. To this end, a bi-plane C-arm system is used to take X-ray images of a special circumferential mapping catheter from two directions. In the first step of the method, a 3D model of the device is reconstructed. Three-dimensional respiratory motion at the site of ablation is then estimated by tracking the reconstructed catheter model in 3D based on bi-plane fluoroscopy. Phantom data and clinical data were used to assess model-based catheter tracking. Our phantom experiments yielded an average 2D tracking error of 1.4 mm and an average 3D tracking error of 1.1 mm. Our evaluation of clinical data sets comprised 469 bi-plane fluoroscopy frames (938 monoplane fluoroscopy frames). We observed an average 2D tracking error of 1.0 ± 0.4 mm and an average 3D tracking error of 0.8 ± 0.5 mm. These results demonstrate that model-based motion-compensation based on 2D/3D registration is both feasible and accurate. Y1 - 2010 U6 - https://doi.org/10.1016/j.media.2010.05.006 VL - 14 IS - 5 SP - 695 EP - 706 ER - TY - CHAP A1 - Hohl, C. A1 - Boese, Jan A1 - Strobel, Norbert A1 - Banckwitz, R. A1 - Mühlenbruch, G. A1 - Günther, R. W. A1 - Honnef, D. T1 - Angiographische CT: Messung der Strahlenexposition bei Kindern T2 - RöFo: Fortschritte auf dem Gebiet Röntgenstrahlen und bildgebenden Verfahren N2 - Ziele: Messung der Organ- und Effektivdosen bei Angiographischen CT-Untersuchungen (ACT) des Kopfs und des Herzens mit einem pädiatrischen anthropomorphen Phantom und Thermolumineszenz Dosimetern (TLD). Methode: ACT erlaubt die Schnittbildgebung von Weichteilstrukturen bei der Verwendung einer C-Bogen Durchleuchtungseinheit mit Flachbilddetektor. Bei Kindern wird die ACT für interventionelle Eingriffe bei angeborenen Herzfehlern oder bei Behandlung cerebro-vaskulärer Malformationen genutzt. Um die sowohl die Organdosen als auch die effektiven Dosen bei ACT-gestützten Interventionen im Bereich des Kopfs und des Herzens zu bestimmen, wurde ein anthropomorphes Phantom eines 5-jährigen Jungen (Braden ATOM, CIRS, Norfolk, VA, USA) mit jeweils 132 TLD an 44 Messstellen bestückt. Die Messungen wurden an einem ACT-Systemen (AXIOM Artis dFC, VB31C, Siemens, Forchheim) mit einer Detektorgrößen von 20×20cm durchgeführt. Die Messungen wurden mit vom Hersteller empfohlenen Standard Hoch-Kontrast-Protokollen für cranielle (70kV, 0.36µGy/frame, 126 frames) und cardiale (70kV, 0.54µGy/frame Detektor-Eingangsdosis, 126 frames) Untersuchungen durchgeführt. Nach jeder Messung wurden die TLD entnommen und ausgewertet. Gemäß den ICRP-Empfehlungen sind Organ- und Effektivdosen berechnet worden, die dann mit bekannten Dosiswerten vergleichbarer MSCT-Untersuchungen korreliert wurden. Ergebnis: Die gemessenen effektive Dosiswerte betrugen 0,11 mSv für die cranielle und 0,46 mSv für die cardiale ACT-Untersuchung. Diese Werte waren deutlich niedriger als vergleichbare Literaturwerte für MSCT-Untersuchungen (1,8 mSv craniell und 9 mSv cardial). Schlussfolgerung: Abhängig von der klinischen Anwendung können ACT-Untersuchungen bei Kindern sogar mit einer geringeren Strahlenexposition verbunden sein als vergleichbare MSCT-Untersuchungen. Bei dem Vergleich von Dosiswerten von ACT und MSCT muss jedoch die unterschiedliche Bildqualität und insbesondere der geringere Weichteilkontrast berücksichtigt werden. Y1 - 2008 U6 - https://doi.org/10.1055/s-2008-1073550 VL - 180 IS - S 1 ER - TY - CHAP A1 - Strobel, Norbert A1 - Meissner, Oliver A1 - Boese, Jan A1 - Brunner, Thomas A1 - Heigl, Benno A1 - Hoheisel, Martin A1 - Lauritsch, Günter A1 - Nagel, Markus A1 - Pfister, Marcus A1 - Rührnschopf, Ernst-Peter A1 - Scholz, Bernhard A1 - Schreiber, Bernd A1 - Spahn, Martin A1 - Zellerhoff, Michael A1 - Klingenbeck-Regn, Klaus T1 - 3D Imaging with Flat-Detector C-Arm Systems T2 - Multislice CT - Medical Radiology N2 - Three-dimensional (3D) C-arm computed tomography is a new and innovative imaging technique. It uses two-dimensional (2D) X-ray projections acquired with a flat-panel detector C-arm angiography system to generate CT-like images. To this end, the C-arm system performs a sweep around the patient, acquiring up to several hundred 2D views. They serve as input for 3D cone-beam reconstruction. Resulting voxel data sets can be visualized either as cross-sectional images or as 3D data sets using different volume rendering techniques. Initially targeted at 3D high-contrast neurovascular applications, 3D C-arm imaging has been continuously improved over the years and is now capable of providing CT-like soft-tissue image quality. In combination with 2D fluoroscopic or radiographic imaging, information provided by 3D C-arm imaging can be valuable for therapy planning, guidance, and outcome assessment all in the interventional suite. Y1 - 2009 SN - 978-3-540-33125-4 SN - 978-3-540-33124-7 U6 - https://doi.org/10.1007/978-3-540-33125-4_3 SP - 33 EP - 51 PB - Springer CY - Berlin, Heidelberg ET - 3. ER - TY - CHAP A1 - Strobel, Norbert A1 - Spors, Sascha A1 - Rabenstein, Rudolf ED - Brandstein, Michael ED - Ward, Darren T1 - Joint Audio-Video Signal Processing for Object Localization and Tracking T2 - Microphone Arrays N2 - Applications such as videoconferencing, automatic scene analysis, or security surveillance involving acoustic sources can benefit from object localization within a complex scene. Many single-sensor techniques already exist for this purpose. They are, e.g., based on microphone arrays, video cameras, or range sensors. Since all of these sensors have their specific strengths and weaknesses, it is often advantageous to combine information from various sensor modalities to arrive at more robust position estimates. This chapter presents a joint audio-video signal processing methodology for object localizing and tracking. The approach is based on a decentralized Kalman filter structure modified such that different sensor measurement models can be incorporated. Such a situation is typical for combined audio-video sensing, since different coordinate systems are usually used for the camera system and the microphone array. At first, the decentralized estimation algorithm is presented. Then a speaker localization example is discussed. Finally, some estimation results are shown. T3 - Digital Signal Processing - 4 Y1 - 2001 SN - 978-3-662-04619-7 SN - 978-3-642-07547-6 U6 - https://doi.org/10.1007/978-3-662-04619-7_10 SP - 203 EP - 225 PB - Springer CY - Berlin, Heidelberg ER - TY - CHAP A1 - Strobel, Norbert ED - Girod, B. ED - Greiner, G. ED - Niemann, H. T1 - Fusion of Multisensor Data T2 - Principles of 3D Image Analysis and Synthesis Y1 - 2000 SP - 309 EP - 322 PB - Kluwer Academic Publishers CY - Boston, USA ER - TY - CHAP A1 - Strobel, Norbert A1 - Rabenstein, Rudolf ED - Girod, G. ED - Greiner, G. ED - Niemann, H. T1 - Object Localization using Audio and Video Signals T2 - Principles of 3D Image Analysis and Synthesis Y1 - 2000 SP - 322 EP - 334 PB - Kluwer Academic Publishers CY - Boston, USA ER - TY - THES A1 - Strobel, Norbert A1 - Mitra, Sanjit K. T1 - Multiresolution-based storage, browsing and retrieval for digital image libraries N2 - In this dissertation, the focus is on algorithms for progressive-resolution image transmission, storage and retrieval. The resulting methods are designed to support a fast system response, to provide an intuitive image representation, and to achieve lossless image compression at competitive bit rates. Average interpolation subdivision (AIS) is introduced. It offers a sound mathematical framework for the derivation of algorithms providing the functionality required. To proceed from AIS to image compression, a multiresolution analysis is added. It allows the construction of wavelet transforms and leads to AIS filter banks. For lossless image compression, reversible wavelet transforms (RWTs) are constructed. To that end, an interband prediction structure for AIS filter banks is first derived. Afterwards rounding operations are introduced, and RWTs are assembled. Reversible AIS filter banks deliver acceptable bit rates when applied to the lossless compression of monochrome images. A time-domain filter analysis confirms that AIS filters are nearly optimal given their structural constraints. Better results are still obtainable. They, however, require an enhanced interband prediction framework. If images of arbitrary size are to be ingested into a database, an efficient method is needed to process signal boundaries. It is demonstrated that interband-prediction offers an elegant and practical solution for this task. The reversible AIS filter banks are finally applied to the lossless compression of color images. Color images offer an excellent opportunity for the design of algorithms which are applicable to a much wider range of multispectral imagery. A new lossless compression method is proposed. It executes a reversible wavelet transform first and then applies adaptive spectral transforms to associated color subbands. Very good results have been obtained. Yet, little computational complexity has been added. Simulation results are included. They verify the rationale of this approach. Y1 - 1998 UR - https://api.semanticscholar.org/CorpusID:60343753 PB - Department of Electrical and Computer Engineering, Signal and Image Processing Laboratory CY - Santa Barbara, USA ER - TY - JOUR A1 - Koch, Martin A1 - Hoffmann, Matthias A1 - Pfister, Marcus A1 - Hornegger, Joachim A1 - Strobel, Norbert T1 - Optimized viewing angles for cardiac electrophysiology ablation procedures JF - International Journal of Computer Assisted Radiology and Surgery N2 - Purpose: Catheter ablation is a common treatment option for atrial fibrillation (AF). Interventional C-arm X-ray systems are used for guiding AF procedures, employing standard view positions. Since the projection angles are not adapted to the individual patient anatomy, standard projections do not necessarily offer the best views of important anatomical structures. Using a pre-procedural 3D data set acquired with MRI or CT, suitable ablation sites (lines) can be identified in advance so an ablation plan can be superimposed on fluoroscopic images to guide the procedure. Methods: A method was developed to estimate optimized projection views for biplane X-ray C-arm systems based on planning data for AF ablation procedures. The estimated viewing angles were compared to standard angulations using an objective quality metric, the length of the planned ablation line as seen under X-ray. This method was tested using 35 clinical datasets annotated with planned ablation lines for ipsilateral pulmonary vein isolation. Results: The optimized views computed using the new method yielded 28 % less foreshortening of pre-planned ablation lines on average. In one case, anatomy-based view calculation lead to a 69 % reduction in foreshortening. Conclusion: The commonly used standard views provide reasonable a priori choices, and some improvement is possible by switching among common angulations depending on the treatment region. Further gains are possible by using anatomy-optimized biplane C-arm angulations. Y1 - 2014 U6 - https://doi.org/10.1007/s11548-014-1103-z VL - 10 SP - 651 EP - 664 PB - Springer ER - TY - JOUR A1 - Kurzendorfer, Tanja A1 - Girard, Erin A1 - Gralewski, Kevin A1 - Kleinoeder, Andreas A1 - Kiraly, Atilla P A1 - Strobel, Norbert A1 - Dori, Yoav T1 - New biplane x-ray magnetic resonance image fusion prototype for 3D enhanced cardiac catheterization in congenital heart diseases JF - Journal of Cardiovascular Magnetic Resonance N2 - Background X-ray magnetic resonance fusion (XMRF) is used to enhance fluoroscopically guided catheterization procedures. We present a new method for biplane XMRF involving an augmented fluoroscopy prototype (Siemens, Forchheim, Germany). With this software it is possible to register 3D MRI data to biplane X-ray projections based on internal markers, without the need for a C-arm CT to perform 3D/3D registration. The software supports overlaying volume rendered data as well as multiple surface models. Visualization techniques, such as contour or solid rendering and surface carving are supported to allow for clear presentation of complex 3D structures. Methods We reviewed data obtained with different visualization methods on 20 patients that underwent clinical XMRF procedures. Surface models were generated by threshold based segmentation from high resolution MRA (syngo Twist or Navigator gated 3D flash IR sequence) of structures of interest using Mimics (Leuven, Belgium). Initial registration was achieved through planar alignment of the volume in anterior-posterior (AP) and lateral projections matching anatomical landmarks, such as the heart and vessel borders. In addition, the registration accuracy of the prototype was assessed using a phantom by measuring the maximum distance between a single point and the 3D model boundaries in comparison to the boundaries seen on fluoroscopy. Results The maximum segmentation time was 10 min and the initial registration required less than 30 sec. Registration was performed without the need for contrast injection or additional radiation exposure. The registration error based on phantom measurements was 2.2 ± 1.1 mm in the AP projection and 1.36 ± 0.7 mm in the lateral projection. For surface rendered data, solid rendering with carving provided the optimal display of complex 3D data. In contrast to volume rendering, solid surface rendering provides delineation of the 3D relation between objects and clear visualization of internal structures such as ostia of the vessels and muscle bundles using the carving feature, see Figure 1. Contour rendering offered reasonable visualization for smooth, uncomplicated structures like the atria, but it was not ideal for complex overlapping structures due to missing 3D depth information. When multiple surfaces are loaded, contour rendering was, however, found to be useful in combination with solid rendered structures to provide a see-through 3D relation between multiple structures Conclusions The prototype demonstrated a high level of accuracy for fluoroscopic overlays. Biplane internal marker based registration can be performed quickly, without the need for additional radiation or contrast. We found solid rendering of surface models in combination with carving techniques to be most useful for visualization. This new biplane XMRF technique has the potential to provide enhanced guidance under fluoroscopy by integrating 3D information and to reduce radiation during complicated catheterization procedures. Funding This project is funded by a research grant from Siemens, AG, Healthcare, Forchheim, Germany. The concepts and information presented in this paper are based on research and are not commercially available. Y1 - 2014 U6 - https://doi.org/10.1186/1532-429X-16-S1-O103 VL - 16 IS - Supplement 1 ER - TY - JOUR A1 - Koch, Martin W. A1 - Brost, Alexander A1 - Bourier, Felix A1 - Hornegger, Joachim A1 - Strobel, Norbert T1 - Automatic planning of atrial fibrillation ablation lines using landmark-constrained nonrigid registration JF - Journal of Medical Imaging N2 - Catheter ablation is a common treatment option for drug-refractory atrial fibrillation. In many cases, pulmonary vein isolation is the treatment of choice. With current fluoro overlay methods or electroanatomic mapping systems, it is possible to visualize three-dimensional (3-D) anatomy as well as target ablation lines to provide additional context information. Today, however, these lines need to be set manually before the procedure by the physician, which may interrupt the clinical workflow. As a solution, we present an automatic approach for the planning of ablation target lines. Our method works on surface models extracted from 3-D images. To propose suitable ablation lines, a reference model annotated with reference ablation lines is nonrigidly registered to the model segmented from a new patient’s 3-D data. After registration, the reference plan is transferred from the reference anatomy to the individual patient anatomy. Due to the high anatomical variations observed in clinical practice, additional landmark constraints are employed in the registration process to increase the robustness of our approach. We evaluated our method on 43 clinical datasets by benchmarking it against professionally planned ablation lines and achieved an average error over all datasets of 2.7±2.0  mm . A qualitative evaluation of the ablation planning lines matched clinical expectations. Y1 - 2014 U6 - https://doi.org/10.1117/1.JMI.1.1.015002 VL - 1 IS - 1 ER - TY - GEN A1 - Wu, W. A1 - Chen, T. A1 - Strobel, Norbert A1 - Comaniciu, D. T1 - Method and system for ablation catheter and circumferential mapping catheter tracking in fluoroscopic images (Patent, US 9,002,436) Y1 - 2015 ER - TY - GEN A1 - Barbot, Julien Christian A1 - Kiraly, Atilla Peter A1 - Strobel, Norbert T1 - Localization and tracking of cryo-balloon during interventional fluoroscopy imaging (Patent, US 8989463B2) N2 - A method for the detection of a balloon catheter within a fluoroscopic image, including: removing noise from a fluoroscopic image; detecting edges of a balloon catheter in the fluoroscopic image, wherein the detected edges include subsets of connected edges; extracting an edge subset from the subsets of connected edges; fitting a model to the extracted edge subset; removing outliers of the extracted edge subset based on the fitting of the model; adding the extracted edge subset without the outlier to a data set; repeating the extracting, fitting, removing and adding steps for the remainder of the subsets of connected edges; and fitting the model to the data set, wherein the data set is indicative of the balloon catheter. Y1 - 2015 UR - https://patents.google.com/patent/US8989463B2/en ER - TY - GEN A1 - Schön, N. A1 - Blohm, L. A1 - Dannenmann, T. A1 - Dennerlein, F. A1 - Hoheisel, M. A1 - Strobel, Norbert T1 - Verfahren zur Registrierung eines ersten Koordinatensystems einer ersten medizinischen Bildgebungseinrichtung mit einem zweiten Koordinatensystemeiner zweitenmedizinischen Bildgebungseinrichtung und/oder einem dritten Koordinatensystem eines medizinischen Instruments, welches durchMarker einer medizinischen Navigationseinrichtung definiert ist, und medizinisches Untersuchungs- und/oder Behandlungssystem (Patent, DE 102011006537) Y1 - 2014 ER -