TY - CHAP A1 - Koch, M. A1 - Langenkamp, A. A1 - Kiraly, A. A1 - Brost, A. A1 - Strobel, Norbert A1 - Hornegger, J. T1 - Navigation System with Contact Force Assessment to Guide Pulmonary Vein Isolation Procedures T2 - 23rd Conference of the Society for Medical Innovation and Technology (SMIT) Tel Aviv 01/2011 Y1 - 2011 UR - https://www5.informatik.uni-erlangen.de/Forschung/Publikationen/2011/Koch11-NSW.pdf UR - https://cris.fau.de/publications/113140984/ ER - TY - CHAP A1 - Bourier, F. A1 - Brost, A. A1 - Kleinoeder, A. A1 - Schneider, H.-J. A1 - Heißenhuber, F. A1 - Ganslmeier, P. A1 - Raab, J. A1 - Koch, M. A1 - Hornegger, J. A1 - Strobel, Norbert A1 - Kurzidim, K. T1 - 3D-Visualisation of Cryo-Balloon Ablation Catheters to Evaluate Left Atrial Anatomy for PVI T2 - Venice Arrhythmias 01/2011 Y1 - 2011 UR - https://cris.fau.de/publications/121376684/ ER - TY - CHAP A1 - Bourier, F. A1 - Schneider, H.-J. A1 - Heißenhuber, F. A1 - Ganslmeier, P. A1 - Brost, A. A1 - Koch, M. A1 - Hornegger, J. A1 - Kleinoeder, A. A1 - Kiraly, A. A1 - Barbot, J. A1 - Strobel, Norbert A1 - Kurzidim, K. T1 - Augmented Fluoroscopy to Guide Transseptal Puncture T2 - Venice Arrhythmias 2011 01/2011 Y1 - 2011 ER - TY - CHAP A1 - Bourier, F. A1 - Schneider, H.-J. A1 - Heißenhuber, F. A1 - Ganslmeier, P. A1 - Brost, A. A1 - Koch, M. A1 - Hornegger, J. A1 - Kleinoeder, A. A1 - Kiraly, A. A1 - Barbot, J. A1 - Strobel, Norbert A1 - Kurzidim, K. T1 - Pulmonary Vein Isolation guided by fluoroscopybased 3D-Navigation on a biplane angiography system T2 - Venice Arrhythmias 2011 01/2011 Y1 - 2011 ER - TY - CHAP A1 - Brost, A. A1 - Wimmer, A. A1 - Liao, R. A1 - Hornegger, J. A1 - Strobel, Norbert T1 - Catheter Tracking: Filter-Based vs. Learning-Based T2 - M. Goesele, S. Roth, A. Kuijper, B. Schiele, K. Schindler (eds.) Pattern Recognintion, LNCS, vol. 6376 T2 - Part of the book series: Lecture Notes in Computer Science ((LNIP,volume 6376)) T3 - Lecture Notes in Computer Science - 6376 Y1 - 2010 SN - 978-3-642-15985-5 U6 - https://doi.org/https://doi.org/10.1007/978-3-642-15986-2_30 SP - 293 EP - 302 PB - Springer CY - Berlin, Heidelberg ER - TY - CHAP A1 - Hoffmann, Matthias A1 - Müller, Simone A1 - Kurzidim, Klaus A1 - Strobel, Norbert A1 - Hornegger, Joachim T1 - Robust Identification of Contrasted Frames in Fluoroscopic Images T2 - Bildverarbeitung für die Medizin 2015 N2 - For automatic registration of 3-D models of the left atrium to fluoroscopic images, a reliable classification of images containing contrast agent is necessary. Inspired by previous approaches on contrast agent detection, we propose a learning-based framework which is able to classify contrasted frames more robustly than previous methods, Furthermore, we performed a quantitative evaluation on a clinical data set consisting of 34 angiographies. Our learning-based approach reached a classification rate of 79.5%. The beginning of a contrast injection was detected correctly in 79.4%. Y1 - 2015 SN - 978-3-662-46223-2 SN - 978-3-662-46224-9 U6 - https://doi.org/10.1007/978-3-662-46224-9_6 PB - Springer Vieweg CY - Berlin, Heidelberg ER - TY - CHAP A1 - Hohl, C. A1 - Boese, Jan A1 - Strobel, Norbert A1 - Banckwitz, R. A1 - Lauritsch, G. A1 - Mühlenbruch, G. A1 - Günther, R. W. T1 - Angiographische CT: Messung der Patientendosis T2 - RöFo: Fortschritte auf dem Gebiet Röntgenstrahlen und bildgebenden Verfahren N2 - Ziele: Messung der Organ- und Effektivdosen bei Angiographischen CT-Untersuchungen (ACT) des Kopfs, des Herzens, der Leber sowie der Lendenwirbelsäule (LWS) mit einem anthropomorphen Phantom und Thermolumineszenz Dosimetern (TLD). Methode: ACT erlaubt die Schnittbildgebung von Weichteilstrukturen bei der Verwendung einer C-Bogen Durchleuchtungseinheit mit Flachbilddetektor. Um die sowohl die Organdosen als auch die effektiven Dosen bei ACT-Untersuchungen des Kopfs, des Herzens, der Leber und der LWS zu bestimmen, wurde ein männliches Alderson-Rando-Phantom mit jeweils 129 TLD an 43 Messstellen bestückt. Die Messungen wurden an zwei ACT-Systemen (AXIOM Artis, VB31C, Siemens, Forchheim) mit verschiedenen Detektorgrößen (20×20cm und 30×40cm) durchgeführt. Mit dem 20×20 Detektor wurden der Kopf (70kV, 126 frames, 0,36µGy/frame, 7,9ms/frame), die LWS (90kV, 275 frames, 0,36Gy/frame, 4,9ms/frame) und das Herz (70kV, 126 frames, 0,54µGy/frame, 10,9ms/frame) untersucht. Mit dem 30×40 Detektor wurden der Kopf (84kV, 496 frames, 1,2µGy/frame, 11,6ms/frame) die Leber (90kV, 397 frames, 0,36µGy/frame, 4,9ms/frame) und das Herz (70kV, 248 frames, 0,54µGy/frame, 4,9ms/frame) untersucht. Zusätzlich wurde mit dem 30×40 Detektor noch eine EKG-getriggerte Herz-Untersuchung durchgeführt (992 frames, Phasen-Zentrum 75%, Phasen-Länge 50%, 50% mAs-Modulation). Nach jeder Messung wurden die TLD gewechselt und ausgewertet. Gemäß den ICRP-Empfehlungen sind Organ- und Effektivdosen berechnet worden, die dann mit bekannten Dosiswerten vergleichbarer MSCT-Untersuchungen korreliert wurden. Ergebnis: Die Messungen der effektiven Dosis für den 20×20 Detektor ergaben Werte von 0,2mSv (Kopf), 2,76mSv (LWS) und 1,25mSv (Herz). Mit dem 30×40 Detektor ergaben sich Werte von 2,95mSv (Kopf), 6,71mSv (Leber) und 3,31mSv (Herz, 248 frames). Für die EKG-getriggerte Untersuchung des Herzens ergab sich eine effektive Dosis von 10,88 mSv bei 4 Umläufen (992 frames). Vergleichbare MSCT-Untersuchung belaufen sich auf 2,9mSv (Kopf), 4,8mSv (LWS), 4,3mSv (Leber) und 8,3mSv (Herz). Schlussfolgerung: Da ACT-Systeme mit einer Belichtungsautomatik ausgestattet sind, hängt die effektive Dosis stark vom Patientendurchmesser ab. Bei Messungen mit dem anthropomorphen Phantom konnte gezeigt werden, dass die effektiven Dosen von ACT-Untersuchungen sogar noch unterhalb von vergleichbaren MSCT-Untersuchungen liegen können. Allerdings muss dabei berücksichtigt werden, dass die Bildqualität und insbesondere der Weichteilkontrast nicht vergleichbar sind. Y1 - 2008 U6 - https://doi.org/10.1055/s-2008-1073628 VL - 180 IS - S 1 ER - TY - JOUR A1 - Bourier, Felix A1 - Fahrig, Rebecca A1 - Wang, Paul A1 - Santangeli, Pasquale A1 - Kurzidim, Klaus A1 - Strobel, Norbert A1 - Moore, Teri A1 - Hinkel, Cameron A1 - Al-Ahmad, Amin T1 - Accuracy assessment of catheter guidance technology in electrophysiology procedures: a comparison of a new 3D-based fluoroscopy navigation system to current electroanatomic mapping system JF - Journal of Cardiovascular Electrophysiology N2 - Background: With increasing complexity in electrophysiology (EP) procedures, the use of electroanatomic mapping systems (EAMS) as a supplement to fluoroscopy has become common practice. This is the first study that evaluates spatial and point localization accuracy for 2 current EAMS, CARTO3(®) (Biosense Webster, Diamond Bar, CA, USA) and EnSite Velocity(®) (St. Jude Medical Inc., St. Paul, MN, USA), and for a novel overlay guidance (OG) software (Siemens AG, Forchheim, Germany) in a phantom experiment. Methods and results: A C-arm CT scan was performed on an acrylic phantom containing holes and location markers. Spatial accuracy was assessed for each system using distance measurements involving known markers inside the phantom and properly placed catheters. Anatomical maps of the phantom were acquired by each EAMS, whereas the 3D-based OG software superimposed an overlay image of the phantom, segmented from the C-arm CT data set, onto biplane fluoroscopy. Registration processes and landmark measurements quantitatively assessed the spatial accuracy of each technology with respect to the ground truth phantom. Point localization performance was 0.49 ± 0.25 mm in OG, 0.46 ± 0.17 mm in CARTO3(®) and 0.79 ± 0.83 mm in EnSite(®) . The registration offset between virtual visualization and reality was 1.10 ± 0.52 mm in OG, 1.62 ± 0.77 mm in CARTO3(®) and 2.02 ± 1.21 mm in EnSite(®) . The offset to phantom C-arm CT landmark measurements was 0.30 ± 0.26 mm in OG, 0.24 ± 0.21 mm in CARTO3(®) and 1.32 ± 0.98 mm in EnSite(®) . Conclusions: Each of the evaluated EP guidance systems showed a high level of accuracy; the observed offsets between the virtual 3D visualization and the real phantom were below a clinically relevant threshold of 3 mm. Y1 - 2013 U6 - https://doi.org/10.1111/jce.12264 VL - 25 IS - 1 SP - 74 EP - 83 ER - TY - JOUR A1 - Meyer, Bernhard Christian A1 - Brost, Alexander A1 - Kraitchman, Dara L A1 - Gilson, Wesley D A1 - Strobel, Norbert A1 - Hornegger, Joachim A1 - Lewin, Jonathan S A1 - Wacker, Frank K T1 - Percutaneous punctures with MR imaging guidance: comparison between MR imaging-enhanced fluoroscopic guidance and real-time MR Imaging guidance JF - Radiology N2 - Purpose: To evaluate and compare the technical accuracy and feasibility of magnetic resonance (MR) imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance for percutaneous puncture procedures in phantoms and animals. Materials and methods: The experimental protocol was approved by the institutional animal care and use committee. Punctures were performed in phantoms, aiming for markers (20 each for MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance), and pigs, aiming for anatomic landmarks (10 for MR imaging-enhanced fluoroscopic guidance and five for MR imaging guidance). To guide the punctures, T1-weighted three-dimensional (3D) MR images of the phantom or pig were acquired. Additional axial and coronal T2-weighted images were used to visualize the anatomy in the animals. For MR imaging-enhanced fluoroscopic guidance, phantoms and pigs were transferred to the fluoroscopic system after initial MR imaging and C-arm computed tomography (CT) was performed. C-arm CT and MR imaging data sets were coregistered. Prototype navigation software was used to plan a puncture path with use of MR images and to superimpose it on fluoroscopic images. For real-time MR imaging, an interventional MR imaging prototype for interactive real-time section position navigation was used. Punctures were performed within the magnet bore. After completion, 3D MR imaging was performed to evaluate the accuracy of insertions. Puncture durations were compared by using the log-rank test. The Mann-Whitney U test was applied to compare the spatial errors. Results: In phantoms, the mean total error was 8.6 mm ± 2.8 with MR imaging-enhanced fluoroscopic guidance and 4.0 mm ± 1.2 with real-time MR imaging guidance (P < .001). The mean puncture time was 2 minutes 10 seconds ± 44 seconds with MR imaging-enhanced fluoroscopic guidance and 37 seconds ± 14 with real-time MR imaging guidance (P < .001). In the animal study, a tolerable distance (<1 cm) between target and needle tip was observed for both MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance. The mean total error was 7.7 mm ± 2.4 with MR imaging-enhanced fluoroscopic guidance and 7.9 mm ± 4.9 with real-time MR imaging guidance (P = .77). The mean puncture time was 5 minutes 43 seconds ± 2 minutes 7 seconds with MR imaging-enhanced fluoroscopic guidance and 5 minutes 14 seconds ± 2 minutes 25 seconds with real-time MR imaging guidance (P = .68). Conclusion: Both MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance demonstrated reasonable and similar accuracy in guiding needle placement to selected targets in phantoms and animals. Y1 - 2013 U6 - https://doi.org/10.1148/radiol.12120117 VL - 266 IS - 3 SP - 912 EP - 919 ER - TY - JOUR A1 - Brost, Alexander A1 - Raab, Jens A1 - Kleinoeder, Andreas A1 - Kurzendorfer, Tanja A1 - Bourier, Felix A1 - Koch, Martin A1 - Hoffmann, Matthias A1 - Strobel, Norbert A1 - Kurzidim, Klaus A1 - Hornegger, Joachim T1 - Medizinische Bildverarbeitung für die minimal-invasive Behandlung von Vorhofflimmern JF - Deutsche Zeitschrift für klinische Forschung, Innovation und Praxis (DZKF) Y1 - 2013 UR - https://cris.fau.de/publications/113146704/ VL - 17 IS - 6 SP - 36 EP - 41 PB - Mediengruppe Oberfranken Fachverlage GmbH & Co. KG ER - TY - JOUR A1 - Bourier, Felix A1 - Vukajlovic, Dejan A1 - Brost, Alexander A1 - Hornegger, Joachim A1 - Strobel, Norbert A1 - Kurzidim, Klaus T1 - Pulmonary vein isolation supported by MRI-derived 3D-augmented biplane fluoroscopy: a feasibility study and a quantitative analysis of the accuracy of the technique JF - Journal of Cardiovascular Electrophysiology N2 - Background: Despite the advancement of technology in electroanatomic mapping systems (EAMS), fluoroscopy remains a necessary, basic imaging modality for electrophysiology procedures. We present a feasibility study of new software that enables 3D-augmented fluoroscopy in biplane catheterization laboratories for planning and guidance of pulmonary vein isolation (PVI). The computer-assisted overlay registration accuracy was assessed in a clinical setting using an automatic calculation of overlay projection geometry that was derived from hardware sensors in C-arms, detectors, and patient table. Methods: Consecutive patients (n = 89) underwent left atrium (LA) magnetic resonance imaging MRI scan prior to PVI. Ideal ablation lines encircling the ipsilateral pulmonary veins (PVs) at antral level were drawn onto the segmented LA surface. The 3D-model was superimposed onto biplane fluoroscopy and matched with angiographies of LA and PVs. Three-dimensional-overlay projection geometry was automatically calculated from C-arm, detectors, and table sensors. Accuracy of technique was assessed as alignment of MRI-derived 3D overlay and angiographic LA/PV anatomy. Integrity of registered overlay was quantified using landmark measurements. Results: Alignment offsets were 1.3 ± 1.5 mm in left PV, 1.2 ± 1.5 mm in right PV, and 1.1 ± 1.4 mm in LA roof region. Bravais-Pearson correlation of the landmark measurements was r = 0.978 (s < 0.01), mean offset between landmark distance measurements was 1.4 ± 0.78 mm. Average time needed for overlay registration was 9.5 ± 3.5 seconds. Conclusions: MRI-derived 3D-augmented fluoroscopy demonstrated a high level of accuracy when compared with LA/PV angiography. The new system could be especially useful to guide procedures not supported by EAMS, such as cryotechnique PVI. Y1 - 2012 U6 - https://doi.org/10.1111/jce.12009 VL - 24 IS - 2 SP - 113 EP - 120 ER - TY - JOUR A1 - Brost, Joachim A1 - Wimmer, Andreas A1 - Liao, Rui A1 - Bourier, Felix A1 - Koch, Martin A1 - Strobel, Norbert A1 - Kurzidim, Klaus A1 - Hornegger, Joachim T1 - Constrained registration for motion compensation in atrial fibrillation ablation procedures JF - IEEE Trans Med Imaging N2 - Fluoroscopic overlay images rendered from preoperative volumetric data can provide additional anatomical details to guide physicians during catheter ablation procedures for treatment of atrial fibrillation (AFib). As these overlay images are often compromised by cardiac and respiratory motion, motion compensation methods are needed to keep the overlay images in sync with the fluoroscopic images. So far, these approaches have either required simultaneous biplane imaging for 3-D motion compensation, or in case of monoplane X-ray imaging, provided only a limited 2-D functionality. To overcome the downsides of the previously suggested methods, we propose an approach that facilitates a full 3-D motion compensation even if only monoplane X-ray images are available. To this end, we use a training phase that employs a biplane sequence to establish a patient specific motion model. Afterwards, a constrained model-based 2-D/3-D registration method is used to track a circumferential mapping catheter. This device is commonly used for AFib catheter ablation procedures. Based on the experiments on real patient data, we found that our constrained monoplane 2-D/3-D registration outperformed the unconstrained counterpart and yielded an average 2-D tracking error of 0.6 mm and an average 3-D tracking error of 1.6 mm. The unconstrained 2-D/3-D registration technique yielded a similar 2-D performance, but the 3-D tracking error increased to 3.2 mm mostly due to wrongly estimated 3-D motion components in X-ray view direction. Compared to the conventional 2-D monoplane method, the proposed method provides a more seamless workflow by removing the need for catheter model re-initialization otherwise required when the C-arm view orientation changes. In addition, the proposed method can be straightforwardly combined with the previously introduced biplane motion compensation technique to obtain a good trade-off between accuracy and radiation dose reduction. Y1 - 2012 U6 - https://doi.org/10.1109/tmi.2011.2181184 VL - 31 IS - 4 SP - 870 EP - 881 ER - TY - JOUR A1 - Maier, Andreas A1 - Wigstrom, Lars A1 - Hofmann, Hannes G A1 - Hornegger, Joachim A1 - Zhu, Lei A1 - Strobel, Norbert A1 - Fahrig, Rebecca T1 - Three-dimensional anisotropic adaptive filtering of projection data for noise reduction in cone beam CT JF - Medical Physic N2 - Purpose: The combination of quickly rotating C-arm gantry with digital flat panel has enabled the acquisition of three-dimensional data (3D) in the interventional suite. However, image quality is still somewhat limited since the hardware has not been optimized for CT imaging. Adaptive anisotropic filtering has the ability to improve image quality by reducing the noise level and therewith the radiation dose without introducing noticeable blurring. By applying the filtering prior to 3D reconstruction, noise-induced streak artifacts are reduced as compared to processing in the image domain. Methods: 3D anisotropic adaptive filtering was used to process an ensemble of 2D x-ray views acquired along a circular trajectory around an object. After arranging the input data into a 3D space (2D projections + angle), the orientation of structures was estimated using a set of differently oriented filters. The resulting tensor representation of local orientation was utilized to control the anisotropic filtering. Low-pass filtering is applied only along structures to maintain high spatial frequency components perpendicular to these. The evaluation of the proposed algorithm includes numerical simulations, phantom experiments, and in-vivo data which were acquired using an AXIOM Artis dTA C-arm system (Siemens AG, Healthcare Sector, Forchheim, Germany). Spatial resolution and noise levels were compared with and without adaptive filtering. A human observer study was carried out to evaluate low-contrast detectability. Results: The adaptive anisotropic filtering algorithm was found to significantly improve low-contrast detectability by reducing the noise level by half (reduction of the standard deviation in certain areas from 74 to 30 HU). Virtually no degradation of high contrast spatial resolution was observed in the modulation transfer function (MTF) analysis. Although the algorithm is computationally intensive, hardware acceleration using Nvidia's CUDA Interface provided an 8.9-fold speed-up of the processing (from 1336 to 150 s). Conclusions: Adaptive anisotropic filtering has the potential to substantially improve image quality and/or reduce the radiation dose required for obtaining 3D image data using cone beam CT. Y1 - 2011 U6 - https://doi.org/10.1118/1.3633901 VL - 38 IS - 11 SP - 5896 EP - 5909 ER - TY - JOUR A1 - Yatziv, Liron A1 - Ibarz, Julian A1 - Strobel, Norbert A1 - Datta, Saurabh A1 - Sapiro, Guillermo T1 - Esophagus Silhouette Extraction and Reconstruction From Fluoroscopic Views for Cardiac Ablation Procedure Guidance JF - IEEE Transactions on Information Technology in Biomedicine N2 - Cardiac ablation involves the risk of serious complications when thermal injury to the esophagus occurs. This paper proposes to reduce the risk of such injuries by a proactive visualization technique, improving physician awareness of the esophagus location in the absence of or in addition to a reactive monitoring device such as a thermal probe. This is achieved by combining a graphical representation of the esophagus with live fluoroscopy. Toward this goal, we present an automated method to reconstruct and visualize a 3-D esophagus model from fluoroscopy image sequences acquired using different C-arm viewing directions. In order to visualize the esophagus under fluoroscopy, it is first biomarked by swallowing a contrast agent such as barium. Images obtained in this procedure are then used to automatically extract the 2-D esophagus silhouette and reconstruct a 3-D surface of the esophagus internal wall. Once the 3-D representation has been computed, it can be visualized using fluoroscopy overlay techniques. Compared to 3-D esophagus imaging using CT or C-arm CT, our proposed fluoroscopy method requires low radiation dose and enables a simpler workflow on geometry-calibrated standard C-arm systems. Y1 - 2011 U6 - https://doi.org/10.1109/TITB.2011.2162247 VL - 15 IS - 5 SP - 703 EP - 708 PB - IEEE ER - 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 -