@inproceedings{BourierSchneiderGanslmeieretal., author = {Bourier, F. and Schneider, H.-J. and Ganslmeier, F. and Heißenhuber, F. and Fischer, R. and Brost, A. and Koch, M. and Strobel, Norbert and Hornegger, J. and Kurzidim, K.}, title = {Unterst{\"u}tzung der transseptalen Punktion durch vorherige {\"U}berlagerung eines 3D-Volumens von linkem Atrium und Aorta}, series = {77. Jahrestagung Fr{\"u}hjahrestagung der Gesellschaft f{\"u}r Kardiologie Mannheim 27.04. - 30.04.2011}, booktitle = {77. Jahrestagung Fr{\"u}hjahrestagung der Gesellschaft f{\"u}r Kardiologie Mannheim 27.04. - 30.04.2011}, language = {de} } @inproceedings{KochLangenkampKiralyetal., author = {Koch, M. and Langenkamp, A. and Kiraly, A. and Brost, A. and Strobel, Norbert and Hornegger, J.}, title = {Navigation System with Contact Force Assessment to Guide Pulmonary Vein Isolation Procedures}, series = {23rd Conference of the Society for Medical Innovation and Technology (SMIT) Tel Aviv 01/2011}, booktitle = {23rd Conference of the Society for Medical Innovation and Technology (SMIT) Tel Aviv 01/2011}, language = {en} } @inproceedings{BourierBrostKleinoederetal., author = {Bourier, F. and Brost, A. and Kleinoeder, A. and Schneider, H.-J. and Heißenhuber, F. and Ganslmeier, P. and Raab, J. and Koch, M. and Hornegger, J. and Strobel, Norbert and Kurzidim, K.}, title = {3D-Visualisation of Cryo-Balloon Ablation Catheters to Evaluate Left Atrial Anatomy for PVI}, series = {Venice Arrhythmias 01/2011}, booktitle = {Venice Arrhythmias 01/2011}, language = {en} } @inproceedings{BourierSchneiderHeissenhuberetal., author = {Bourier, F. and Schneider, H.-J. and Heißenhuber, F. and Ganslmeier, P. and Brost, A. and Koch, M. and Hornegger, J. and Kleinoeder, A. and Kiraly, A. and Barbot, J. and Strobel, Norbert and Kurzidim, K.}, title = {Augmented Fluoroscopy to Guide Transseptal Puncture}, series = {Venice Arrhythmias 2011 01/2011}, booktitle = {Venice Arrhythmias 2011 01/2011}, language = {en} } @inproceedings{BourierSchneiderHeissenhuberetal., author = {Bourier, F. and Schneider, H.-J. and Heißenhuber, F. and Ganslmeier, P. and Brost, A. and Koch, M. and Hornegger, J. and Kleinoeder, A. and Kiraly, A. and Barbot, J. and Strobel, Norbert and Kurzidim, K.}, title = {Pulmonary Vein Isolation guided by fluoroscopybased 3D-Navigation on a biplane angiography system}, series = {Venice Arrhythmias 2011 01/2011}, booktitle = {Venice Arrhythmias 2011 01/2011}, language = {en} } @inproceedings{BrostWimmerLiaoetal., author = {Brost, A. and Wimmer, A. and Liao, R. and Hornegger, J. and Strobel, Norbert}, title = {Catheter Tracking: Filter-Based vs. Learning-Based}, series = {M. Goesele, S. Roth, A. Kuijper, B. Schiele, K. Schindler (eds.) Pattern Recognintion, LNCS, vol. 6376}, booktitle = {M. Goesele, S. Roth, A. Kuijper, B. Schiele, K. Schindler (eds.) Pattern Recognintion, LNCS, vol. 6376}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-642-15985-5}, doi = {https://doi.org/10.1007/978-3-642-15986-2_30}, pages = {293 -- 302}, language = {en} } @incollection{HoffmannMuellerKurzidimetal., author = {Hoffmann, Matthias and M{\"u}ller, Simone and Kurzidim, Klaus and Strobel, Norbert and Hornegger, Joachim}, title = {Robust Identification of Contrasted Frames in Fluoroscopic Images}, series = {Bildverarbeitung f{\"u}r die Medizin 2015}, booktitle = {Bildverarbeitung f{\"u}r die Medizin 2015}, publisher = {Springer Vieweg}, address = {Berlin, Heidelberg}, isbn = {978-3-662-46223-2}, doi = {10.1007/978-3-662-46224-9_6}, abstract = {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\%.}, language = {en} } @inproceedings{HohlBoeseStrobeletal., author = {Hohl, C. and Boese, Jan and Strobel, Norbert and Banckwitz, R. and Lauritsch, G. and M{\"u}hlenbruch, G. and G{\"u}nther, R. W.}, title = {Angiographische CT: Messung der Patientendosis}, series = {R{\"o}Fo: Fortschritte auf dem Gebiet R{\"o}ntgenstrahlen und bildgebenden Verfahren}, volume = {180}, booktitle = {R{\"o}Fo: Fortschritte auf dem Gebiet R{\"o}ntgenstrahlen und bildgebenden Verfahren}, number = {S 1}, doi = {10.1055/s-2008-1073628}, abstract = {Ziele: Messung der Organ- und Effektivdosen bei Angiographischen CT-Untersuchungen (ACT) des Kopfs, des Herzens, der Leber sowie der Lendenwirbels{\"a}ule (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 m{\"a}nnliches Alderson-Rando-Phantom mit jeweils 129 TLD an 43 Messstellen best{\"u}ckt. Die Messungen wurden an zwei ACT-Systemen (AXIOM Artis, VB31C, Siemens, Forchheim) mit verschiedenen Detektorgr{\"o}ßen (20×20cm und 30×40cm) durchgef{\"u}hrt. 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. Zus{\"a}tzlich wurde mit dem 30×40 Detektor noch eine EKG-getriggerte Herz-Untersuchung durchgef{\"u}hrt (992 frames, Phasen-Zentrum 75\%, Phasen-L{\"a}nge 50\%, 50\% mAs-Modulation). Nach jeder Messung wurden die TLD gewechselt und ausgewertet. Gem{\"a}ß 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 f{\"u}r 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). F{\"u}r die EKG-getriggerte Untersuchung des Herzens ergab sich eine effektive Dosis von 10,88 mSv bei 4 Uml{\"a}ufen (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, h{\"a}ngt 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 k{\"o}nnen. Allerdings muss dabei ber{\"u}cksichtigt werden, dass die Bildqualit{\"a}t und insbesondere der Weichteilkontrast nicht vergleichbar sind.}, language = {de} } @article{BourierFahrigWangetal., author = {Bourier, Felix and Fahrig, Rebecca and Wang, Paul and Santangeli, Pasquale and Kurzidim, Klaus and Strobel, Norbert and Moore, Teri and Hinkel, Cameron and Al-Ahmad, Amin}, title = {Accuracy assessment of catheter guidance technology in electrophysiology procedures: a comparison of a new 3D-based fluoroscopy navigation system to current electroanatomic mapping system}, series = {Journal of Cardiovascular Electrophysiology}, volume = {25}, journal = {Journal of Cardiovascular Electrophysiology}, number = {1}, doi = {10.1111/jce.12264}, pages = {74 -- 83}, abstract = {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.}, language = {en} } @article{MeyerBrostKraitchmanetal., author = {Meyer, Bernhard Christian and Brost, Alexander and Kraitchman, Dara L and Gilson, Wesley D and Strobel, Norbert and Hornegger, Joachim and Lewin, Jonathan S and Wacker, Frank K}, title = {Percutaneous punctures with MR imaging guidance: comparison between MR imaging-enhanced fluoroscopic guidance and real-time MR Imaging guidance}, series = {Radiology}, volume = {266}, journal = {Radiology}, number = {3}, doi = {10.1148/radiol.12120117}, pages = {912 -- 919}, abstract = {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.}, language = {en} } @article{BrostRaabKleinoederetal., author = {Brost, Alexander and Raab, Jens and Kleinoeder, Andreas and Kurzendorfer, Tanja and Bourier, Felix and Koch, Martin and Hoffmann, Matthias and Strobel, Norbert and Kurzidim, Klaus and Hornegger, Joachim}, title = {Medizinische Bildverarbeitung f{\"u}r die minimal-invasive Behandlung von Vorhofflimmern}, series = {Deutsche Zeitschrift f{\"u}r klinische Forschung, Innovation und Praxis (DZKF)}, volume = {17}, journal = {Deutsche Zeitschrift f{\"u}r klinische Forschung, Innovation und Praxis (DZKF)}, number = {6}, publisher = {Mediengruppe Oberfranken Fachverlage GmbH \& Co. KG}, pages = {36 -- 41}, language = {en} } @article{BourierVukajlovicBrostetal., author = {Bourier, Felix and Vukajlovic, Dejan and Brost, Alexander and Hornegger, Joachim and Strobel, Norbert and Kurzidim, Klaus}, title = {Pulmonary vein isolation supported by MRI-derived 3D-augmented biplane fluoroscopy: a feasibility study and a quantitative analysis of the accuracy of the technique}, series = {Journal of Cardiovascular Electrophysiology}, volume = {24}, journal = {Journal of Cardiovascular Electrophysiology}, number = {2}, doi = {10.1111/jce.12009}, pages = {113 -- 120}, abstract = {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.}, language = {en} } @article{BrostWimmerLiaoetal., author = {Brost, Joachim and Wimmer, Andreas and Liao, Rui and Bourier, Felix and Koch, Martin and Strobel, Norbert and Kurzidim, Klaus and Hornegger, Joachim}, title = {Constrained registration for motion compensation in atrial fibrillation ablation procedures}, series = {IEEE Trans Med Imaging}, volume = {31}, journal = {IEEE Trans Med Imaging}, number = {4}, doi = {10.1109/tmi.2011.2181184}, pages = {870 -- 881}, abstract = {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.}, language = {en} } @article{MaierWigstromHofmannetal., author = {Maier, Andreas and Wigstrom, Lars and Hofmann, Hannes G and Hornegger, Joachim and Zhu, Lei and Strobel, Norbert and Fahrig, Rebecca}, title = {Three-dimensional anisotropic adaptive filtering of projection data for noise reduction in cone beam CT}, series = {Medical Physic}, volume = {38}, journal = {Medical Physic}, number = {11}, doi = {10.1118/1.3633901}, pages = {5896 -- 5909}, abstract = {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.}, language = {en} } @article{YatzivIbarzStrobeletal., author = {Yatziv, Liron and Ibarz, Julian and Strobel, Norbert and Datta, Saurabh and Sapiro, Guillermo}, title = {Esophagus Silhouette Extraction and Reconstruction From Fluoroscopic Views for Cardiac Ablation Procedure Guidance}, series = {IEEE Transactions on Information Technology in Biomedicine}, volume = {15}, journal = {IEEE Transactions on Information Technology in Biomedicine}, number = {5}, publisher = {IEEE}, doi = {10.1109/TITB.2011.2162247}, pages = {703 -- 708}, abstract = {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.}, language = {en} } @inproceedings{BrostWuKochetal., author = {Brost, Alexander and Wu, Wen and Koch, Martin and Wimmer, Martin and Chen, Terrence and Liao, Rui and Hornegger, Joachim and Strobel, Norbert}, title = {Combined Cardiac and Respiratory Motion Compensation for Atrial Fibrillation Ablation Procedures}, series = {Medical Image Computing and Computer-Assisted Intervention}, volume = {14}, booktitle = {Medical Image Computing and Computer-Assisted Intervention}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-642-23622-8}, doi = {10.1007/978-3-642-23623-5_68}, pages = {540 -- 547}, abstract = {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 \%.}, language = {en} } @article{BrostLiaoStrobeletal., author = {Brost, Alexander and Liao, Rui and Strobel, Norbert and Hornegger, Joachim}, title = {Respiratory motion compensation by model-based catheter tracking during EP procedures}, series = {Medical Image Analysis}, volume = {14}, journal = {Medical Image Analysis}, number = {5}, doi = {10.1016/j.media.2010.05.006}, pages = {695 -- 706}, abstract = {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.}, language = {en} } @inproceedings{HohlBoeseStrobeletal., author = {Hohl, C. and Boese, Jan and Strobel, Norbert and Banckwitz, R. and M{\"u}hlenbruch, G. and G{\"u}nther, R. W. and Honnef, D.}, title = {Angiographische CT: Messung der Strahlenexposition bei Kindern}, series = {R{\"o}Fo: Fortschritte auf dem Gebiet R{\"o}ntgenstrahlen und bildgebenden Verfahren}, volume = {180}, booktitle = {R{\"o}Fo: Fortschritte auf dem Gebiet R{\"o}ntgenstrahlen und bildgebenden Verfahren}, number = {S 1}, doi = {10.1055/s-2008-1073550}, abstract = {Ziele: Messung der Organ- und Effektivdosen bei Angiographischen CT-Untersuchungen (ACT) des Kopfs und des Herzens mit einem p{\"a}diatrischen 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 f{\"u}r interventionelle Eingriffe bei angeborenen Herzfehlern oder bei Behandlung cerebro-vaskul{\"a}rer Malformationen genutzt. Um die sowohl die Organdosen als auch die effektiven Dosen bei ACT-gest{\"u}tzten Interventionen im Bereich des Kopfs und des Herzens zu bestimmen, wurde ein anthropomorphes Phantom eines 5-j{\"a}hrigen Jungen (Braden ATOM, CIRS, Norfolk, VA, USA) mit jeweils 132 TLD an 44 Messstellen best{\"u}ckt. Die Messungen wurden an einem ACT-Systemen (AXIOM Artis dFC, VB31C, Siemens, Forchheim) mit einer Detektorgr{\"o}ßen von 20×20cm durchgef{\"u}hrt. Die Messungen wurden mit vom Hersteller empfohlenen Standard Hoch-Kontrast-Protokollen f{\"u}r cranielle (70kV, 0.36µGy/frame, 126 frames) und cardiale (70kV, 0.54µGy/frame Detektor-Eingangsdosis, 126 frames) Untersuchungen durchgef{\"u}hrt. Nach jeder Messung wurden die TLD entnommen und ausgewertet. Gem{\"a}ß 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 f{\"u}r die cranielle und 0,46 mSv f{\"u}r die cardiale ACT-Untersuchung. Diese Werte waren deutlich niedriger als vergleichbare Literaturwerte f{\"u}r MSCT-Untersuchungen (1,8 mSv craniell und 9 mSv cardial). Schlussfolgerung: Abh{\"a}ngig von der klinischen Anwendung k{\"o}nnen 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 Bildqualit{\"a}t und insbesondere der geringere Weichteilkontrast ber{\"u}cksichtigt werden.}, language = {de} } @incollection{StrobelMeissnerBoeseetal., author = {Strobel, Norbert and Meissner, Oliver and Boese, Jan and Brunner, Thomas and Heigl, Benno and Hoheisel, Martin and Lauritsch, G{\"u}nter and Nagel, Markus and Pfister, Marcus and R{\"u}hrnschopf, Ernst-Peter and Scholz, Bernhard and Schreiber, Bernd and Spahn, Martin and Zellerhoff, Michael and Klingenbeck-Regn, Klaus}, title = {3D Imaging with Flat-Detector C-Arm Systems}, series = {Multislice CT - Medical Radiology}, booktitle = {Multislice CT - Medical Radiology}, edition = {3.}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-540-33125-4}, doi = {10.1007/978-3-540-33125-4_3}, pages = {33 -- 51}, abstract = {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.}, language = {en} } @incollection{StrobelSporsRabenstein, author = {Strobel, Norbert and Spors, Sascha and Rabenstein, Rudolf}, title = {Joint Audio-Video Signal Processing for Object Localization and Tracking}, series = {Microphone Arrays}, booktitle = {Microphone Arrays}, editor = {Brandstein, Michael and Ward, Darren}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-662-04619-7}, doi = {10.1007/978-3-662-04619-7_10}, pages = {203 -- 225}, abstract = {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.}, language = {en} }