@article{SzeStrobelFahrigetal., author = {Sze, Daniel Y. and Strobel, Norbert and Fahrig, Rebecca and Moore, Teri and Busque, Stephan and Frisoli, Joan K.}, title = {Transjugular intrahepatic portosystemic shunt creation in a polycystic liver facilitated by hybrid cross-sectional/angiographic imaging}, series = {Journal of Vascular and Interventional Radiology (JVIR)}, volume = {17}, journal = {Journal of Vascular and Interventional Radiology (JVIR)}, number = {4}, doi = {10.1097/01.rvi.0000208984.17697.58}, pages = {711 -- 715}, abstract = {Polycystic liver disease (PCLD) has long been considered to represent a contraindication to transjugular intrahepatic portosystemic shunt (TIPS) creation, primarily because of the risk of hemorrhage. Three-dimensional (3D) navigation within the enlarged and potentially disorienting parenchyma can now be performed during the procedure with the development of C-arm cone-beam computed tomography, which relies on the same equipment already used for angiography. Such a hybrid 3D reconstruction-enabled angiography system was used for safe image guidance of a TIPS procedure in a patient with PCLD. This technology has the potential to expedite any image-guided procedure that requires 3D navigation.}, language = {en} } @article{StrobelSporsRabenstein, author = {Strobel, Norbert and Spors, Sascha and Rabenstein, Rudolf}, title = {Joint audio-video object localization and tracking}, series = {IEEE Signal Processing Magazine}, volume = {18}, journal = {IEEE Signal Processing Magazine}, number = {1}, publisher = {IEEE}, doi = {10.1109/79.911196}, pages = {22 -- 31}, abstract = {There has been a tremendous amount of research on object localization either involving microphone arrays or video cameras. Considerable less attention has been paid, however, to object localization and tracking based on joint audio-video processing thus far. This may be related to the lack of suitable algorithms for object localization simultaneously using multimicrophone outputs and color image sequences. In this article, we propose a solution to this problem. Before elaborating on joint audio-video processing, we review some previous work the areas of audio and video object localization. Then a recursive sensor fusion method based on decentralized Kalman filtering is introduced. Unfortunately, the decentralized Kalman filter cannot be directly used for joint audio-video object localization due to specific properties of the audio sensor. By properly adjusting the local audio position estimator, however, we manage to keep the overall architecture. We stress the general methodology.}, language = {en} } @article{RamponiStrobelMitraetal., author = {Ramponi, Giovanni and Strobel, Norbert and Mitra, Sanjit K. and Yu, Tian-Hu}, title = {Nonlinear unsharp masking methods for image contrast enhancement}, series = {Journal of Electronic Imaging}, volume = {5}, journal = {Journal of Electronic Imaging}, number = {3}, doi = {10.1117/12.242618}, pages = {353 -- 366}, abstract = {In the unsharp masking approach for image enhancement, a fraction of the highpass filtered version of the image is added to the original image to form the enhanced version. The method is simple, but it suffers from two serious drawbacks. First, it enhances the contrast in the darker areas perceptually much more strongly than that in the lighter areas. Second, it enhances the noise and/or digitization effects, particularly in the darker regions, resulting in visually less pleasing enhanced images. In general, noise can be suppressed with lowpass filters, which are associated with the blurring of the edges. On the other hand, contrast can be enhanced with highpass filters, which are associated with noise amplification. A reasonable solution, therefore, is to use suitable nonlinear filters which combine the features of both highpass and lowpass filters. This paper outlines several new methods of unsharp masking based on the use of such nonlinear filters. Computer simulations have verified the superior results obtained using these filters. In addition, a new measure of contrast enhancement is introduced which quantitatively supports the improvement obtained using the proposed methods.}, language = {en} } @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} } @incollection{Strobel, author = {Strobel, Norbert}, title = {Fusion of Multisensor Data}, series = {Principles of 3D Image Analysis and Synthesis}, booktitle = {Principles of 3D Image Analysis and Synthesis}, editor = {Girod, B. and Greiner, G. and Niemann, H.}, publisher = {Kluwer Academic Publishers}, address = {Boston, USA}, pages = {309 -- 322}, language = {en} } @incollection{StrobelRabenstein, author = {Strobel, Norbert and Rabenstein, Rudolf}, title = {Object Localization using Audio and Video Signals}, series = {Principles of 3D Image Analysis and Synthesis}, booktitle = {Principles of 3D Image Analysis and Synthesis}, editor = {Girod, G. and Greiner, G. and Niemann, H.}, publisher = {Kluwer Academic Publishers}, address = {Boston, USA}, pages = {322 -- 334}, language = {en} } @phdthesis{StrobelMitra, author = {Strobel, Norbert and Mitra, Sanjit K.}, title = {Multiresolution-based storage, browsing and retrieval for digital image libraries}, publisher = {Department of Electrical and Computer Engineering, Signal and Image Processing Laboratory}, address = {Santa Barbara, USA}, abstract = {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.}, language = {en} } @article{KochHoffmannPfisteretal., author = {Koch, Martin and Hoffmann, Matthias and Pfister, Marcus and Hornegger, Joachim and Strobel, Norbert}, title = {Optimized viewing angles for cardiac electrophysiology ablation procedures}, series = {International Journal of Computer Assisted Radiology and Surgery}, volume = {10}, journal = {International Journal of Computer Assisted Radiology and Surgery}, publisher = {Springer}, doi = {10.1007/s11548-014-1103-z}, pages = {651 -- 664}, abstract = {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.}, language = {en} } @article{KurzendorferGirardGralewskietal., author = {Kurzendorfer, Tanja and Girard, Erin and Gralewski, Kevin and Kleinoeder, Andreas and Kiraly, Atilla P and Strobel, Norbert and Dori, Yoav}, title = {New biplane x-ray magnetic resonance image fusion prototype for 3D enhanced cardiac catheterization in congenital heart diseases}, series = {Journal of Cardiovascular Magnetic Resonance}, volume = {16}, journal = {Journal of Cardiovascular Magnetic Resonance}, number = {Supplement 1}, doi = {10.1186/1532-429X-16-S1-O103}, abstract = {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.}, language = {en} } @article{KochBrostBourieretal., author = {Koch, Martin W. and Brost, Alexander and Bourier, Felix and Hornegger, Joachim and Strobel, Norbert}, title = {Automatic planning of atrial fibrillation ablation lines using landmark-constrained nonrigid registration}, series = {Journal of Medical Imaging}, volume = {1}, journal = {Journal of Medical Imaging}, number = {1}, doi = {10.1117/1.JMI.1.1.015002}, abstract = {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.}, language = {en} } @misc{WuChenStrobeletal., author = {Wu, W. and Chen, T. and Strobel, Norbert and Comaniciu, D.}, title = {Method and system for ablation catheter and circumferential mapping catheter tracking in fluoroscopic images (Patent, US 9,002,436)}, language = {en} } @misc{BarbotKiralyStrobel, author = {Barbot, Julien Christian and Kiraly, Atilla Peter and Strobel, Norbert}, title = {Localization and tracking of cryo-balloon during interventional fluoroscopy imaging (Patent, US 8989463B2)}, abstract = {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.}, language = {en} } @misc{SchoenBlohmDannenmannetal., author = {Sch{\"o}n, N. and Blohm, L. and Dannenmann, T. and Dennerlein, F. and Hoheisel, M. and Strobel, Norbert}, title = {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)}, language = {de} } @misc{DennerleinBlohmVogtetal., author = {Dennerlein, F. and Blohm, L. and Vogt, M. and Hoheisel, M. and Sch{\"o}n, N. and Strobel, Norbert and Dannenmann, T.}, title = {Verfahren und System zur Unterst{\"u}tzung des Arbeitsablaufs in einer Operationsumgebung (Patent, DE102011006574)}, language = {de} } @inproceedings{HariharanKaethnerStrobeletal., author = {Hariharan, Sai Gokul and Kaethner, Christian and Strobel, Norbert and Kowarschik, Markus and Albarqouni, Shadi and Fahrig, Rebecca and Navab, Nassir}, title = {Learning-based X-ray image denoising utilizing model-based image simulations}, series = {International Conference on Medical Image Computing and Computer-Assisted Intervention - MICCAI 2019, 22nd International Conference Shenzhen, China, October 13-17, 2019 Proceedings, Part VI}, booktitle = {International Conference on Medical Image Computing and Computer-Assisted Intervention - MICCAI 2019, 22nd International Conference Shenzhen, China, October 13-17, 2019 Proceedings, Part VI}, publisher = {Springer International Publishing}, address = {Cham}, doi = {10.1007/978-3-030-32226-7_61}, pages = {549 -- 557}, language = {en} } @inproceedings{HariharanKaethnerStrobeletal., author = {Hariharan, Sai Gokul and Kaethner, Christian and Strobel, Norbert and Kowarschik, Markus and DiNitto, Julie and Fahrig, Rebecca and Navab, Nassir}, title = {Model-based motion artifact correction in digital subtraction angiography using optical-flow}, series = {Bildverarbeitung f{\"u}r die Medizin 2019: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 17. bis 19. M{\"a}rz 2019 in L{\"u}beck}, booktitle = {Bildverarbeitung f{\"u}r die Medizin 2019: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 17. bis 19. M{\"a}rz 2019 in L{\"u}beck}, publisher = {Springer Fachmedien}, address = {Wiesbaden}, doi = {10.1007/978-3-658-25326-4_31}, pages = {146 -- 151}, language = {en} } @inproceedings{SpiessFriesslichBluemmetal., author = {Spieß, Florian and Friesslich, Jonas and Bluemm, Daniel and Mast, Fabio and Vinokour, Dmitrij and Kounev, Samuel and Kaupp, Tobias and Strobel, Norbert}, title = {Towards a Mobile Robot Localization Benchmark with Challenging Sensordata in an Industrial Environment}, series = {2021 20th International Conference on Advanced Robotics (ICAR)}, booktitle = {2021 20th International Conference on Advanced Robotics (ICAR)}, doi = {10.1109/ICAR53236.2021.9659355}, pages = {857 -- 864}, abstract = {To arrive at a realistic assessment of localization methods in terms of their performance in an industrial environment under various challenging conditions, we provide a benchmark to evaluate algorithms both for individual components as well as multi-sensor systems. For several sensor types, including wheel odometry, RGB cameras, RGB-D cameras, and LIDAR, potential issues were identified. The accuracy of wheel odometry, for example, when there are bumps on the track. For each sensor type, we explicitly chose a track for the benchmark dataset containing situations where the sensor fails to provide adequate measurements. Based on the acquired sensor data, localization can be achieved either using a single sensor information or sensor fusion. To help evaluate the output of associated localization algorithms, we provide a software to evaluate a set of metrics as part of the paper. An example application of the benchmark with state-of-the-art algorithms for each sensor is also provided.}, language = {en} } @article{SpiessReinhartStrobeletal., author = {Spiess, Florian and Reinhart, Lukas and Strobel, Norbert and Kaupp, Tobias and Kaiser, Dennis and Kounev, Samuel}, title = {People detection with depth silhouettes and convolutional neural networks on a mobile robot}, series = {Journal of Image and Graphics}, volume = {9}, journal = {Journal of Image and Graphics}, number = {4}, pages = {135 -- 139}, abstract = {This paper presents a novel people detection approach for mobile robot applications based on a combination of classical computer vision techniques and a state-of-the-art neural network. Our approach involves an RGB-D camera as an environmental sensor. The depth data is used to extract silhouettes around people. The RGB images are subsequently augmented with this border information before passing it to the neural network. Under challenging lighting conditions, our system was able to outperform the neural network trained on regular RGB data alone by a factor of two.}, language = {en} } @inproceedings{SpiessStrobelKauppetal., author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, title = {A data-driven Sensor Model for LIDAR Range Measurements used for Mobile Robot Navigation}, series = {2022 Sixth IEEE International Conference on Robotic Computing (IRC)}, booktitle = {2022 Sixth IEEE International Conference on Robotic Computing (IRC)}, doi = {10.1109/IRC55401.2022.00020}, pages = {76 -- 80}, abstract = {In this paper, an analysis of the precision of LIDAR range measurements is presented. LIDAR data from two different sensors (HLS-LFCD-LDS and SICK TIM561) were analyzed regarding the influence of range, incident angle to the surface, and material. Based on the results, a data-driven model for LIDAR precision behavior was developed, and a comparison with standard deviation models based on the vendor-provided specifications was presented. Our model can be used to create realistic sensor simulations and to develop robot navigation algorithms weighing sensor range readings based on the precision.}, language = {en} } @article{SpiessFriesslichKauppetal., author = {Spiess, Florian and Friesslich, Jonas and Kaupp, Tobias and Kounev, Samuel and Strobel, Norbert}, title = {Survey and Experimental Comparison of RGB-D Indoor Robot Navigation Methods Supported by ROS and Their Expansion via Fusion with Wheel Odometry and IMU Data}, series = {International Journal of Mechanical Engineering and Robotics Research}, volume = {9}, journal = {International Journal of Mechanical Engineering and Robotics Research}, number = {12}, doi = {10.18178/ijmerr.9.12.1532-1540}, pages = {1532 -- 1540}, language = {en} } @article{SpiessStrobelKauppetal., author = {Spiess, Florian and Strobel, Norbert and Kaupp, Tobias and Kounev, Samuel}, title = {A data-driven Model for Range Sensors}, series = {Encyclopedia with Semantic Computing and Robotic Intelligence}, journal = {Encyclopedia with Semantic Computing and Robotic Intelligence}, language = {en} } @inproceedings{RoserZhongBirkholdetal., author = {Roser, Philipp and Zhong, Xia and Birkhold, Annette and Preuhs, Alexander and Syben, Christopher and Hoppe, Elisabeth and Strobel, Norbert and Kowarschik, Markus and Fahrig, Rebecca and Maier, Andreas}, title = {Simultaneous estimation of X-ray back-scatter and forward-scatter using multi-task learning}, series = {Medical Image Computing and Computer Assisted Intervention-MICCAI 2020: 23rd International Conference, Lima, Peru, October 4-8, 2020, Proceedings, Part II 23}, booktitle = {Medical Image Computing and Computer Assisted Intervention-MICCAI 2020: 23rd International Conference, Lima, Peru, October 4-8, 2020, Proceedings, Part II 23}, publisher = {Springer International Publishing}, doi = {10.1007/978-3-030-59713-9_20}, pages = {199 -- 208}, language = {en} } @inproceedings{ZhongRoserBayeretal., author = {Zhong, Xia and Roser, Philipp and Bayer, Siming and Ravikumar, Nishant and Strobel, Norbert and Birkhold, Annette and Horz, Tim and Kowarschik, Markus and Fahrig, Rebecca and Maier, Andreas}, title = {Pediatric Patient Surface Model Atlas Generation and X-Ray Skin Dose Estimation}, series = {Bildverarbeitung f{\"u}r die Medizin 2019: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 17. bis 19. M{\"a}rz 2019 in L{\"u}beck}, booktitle = {Bildverarbeitung f{\"u}r die Medizin 2019: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 17. bis 19. M{\"a}rz 2019 in L{\"u}beck}, publisher = {Springer Fachmedien}, address = {Wiesbaden}, doi = {10.1007/978-3-658-25326-4_27}, pages = {122 -- 127}, language = {en} } @inproceedings{RoserBirkholdPreuhsetal., author = {Roser, Philipp and Birkhold, Annette and Preuhs, Alexander and Syben, Christopher and Strobel, Norbert and Kowarschik, Markus and Fahrig, Rebecca and Maier, Andreas}, title = {Deep scatter splines: Learning-based medical X-ray scatter estimation using B-splines}, series = {The 6th International Conference on Image Formation in X-Ray Computed Tompgraphy}, booktitle = {The 6th International Conference on Image Formation in X-Ray Computed Tompgraphy}, language = {en} } @inproceedings{ShettyBirkholdStrobeletal., author = {Shetty, Karthik and Birkhold, Annette and Strobel, Norbert and Egger, Bernhard and Jaganathan, Srikrishna and Kowarschik, Markus and Maier, Andreas}, title = {Deep Learning Compatible Differentiable X-ray Projections for Inverse Rendering}, series = {Bildverarbeitung f{\"u}r die Medizin 2021: Proceedings, German Workshop on Medical Image Computing, Regensburg, March 7-9}, booktitle = {Bildverarbeitung f{\"u}r die Medizin 2021: Proceedings, German Workshop on Medical Image Computing, Regensburg, March 7-9}, publisher = {Springer Fachmedien}, address = {Wiesbaden}, pages = {290 -- 295}, language = {en} } @inproceedings{ShettyBirkholdJaganathanetal., author = {Shetty, Karthik and Birkhold, Annette and Jaganathan, Srikrishna and Strobel, Norbert and Kowarschik, Markus and Maier, Andreas and Egger, Bernhard}, title = {PLIKS - A Pseudo-Linear Inverse Kinematic Solver for3D Human Body Estimation}, series = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition}, booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition}, pages = {574 -- 584}, language = {en} } @article{HariharanKaethnerStrobeletal., author = {Hariharan, Sai Gokul and Kaethner, Christian and Strobel, Norbert and Kowarschik, Markus and Fahrig, Rebecca and Navab, Nassir}, title = {Robust learning-based x-ray image denoising—potential pitfalls, their analysis and solutions}, series = {Biomedical Physics \& Engineering Express}, volume = {8}, journal = {Biomedical Physics \& Engineering Express}, number = {3}, doi = {10.1088/2057-1976/ac3489}, language = {en} } @article{MaulRoserBirkholdetal., author = {Maul, Noah and Roser, Philipp and Birkhold, Annette and Kowarschik, Markus and Zhong, Xia and Strobel, Norbert and Maier, Andreas}, title = {Learning-based occupational x-ray scatter estimation}, series = {Physics in Medicine and Biology}, volume = {67}, journal = {Physics in Medicine and Biology}, number = {7}, doi = {10.1088/1361-6560/ac58dc}, language = {en} } @article{ZhongAmrehnRavikumaretal., author = {Zhong, Xia and Amrehn, Mario and Ravikumar, Nishant and Chen, Shuqing and Strobel, Norbert and Birkhold, Annette and Kowarschik, Markus and Fahrig, Rebecca and Maier, Andreas}, title = {Deep action learning enables robust 3D segmentation of body organs in various CT and MRI images}, series = {Scientific Reports}, volume = {11}, journal = {Scientific Reports}, number = {1}, doi = {10.1038/s41598-021-82370-6}, language = {en} } @article{RoserBirkholdPreuhsetal., author = {Roser, Philipp and Birkhold, Annette and Preuhs, Alexander and Stimpel, Bernhard and Syben, Christopher and Strobel, Norbert and Kowarschik, Markus and Fahrig, Rebecca and Maier, Andreas}, title = {Fully-automatic CT data preparation for interventional X-ray skin dose simulation}, series = {Bildverarbeitung f{\"u}r die Medizin 2020: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 15. bis 17. M{\"a}rz 2020 in Berlin}, journal = {Bildverarbeitung f{\"u}r die Medizin 2020: Algorithmen - Systeme - Anwendungen. Proceedings des Workshops vom 15. bis 17. 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