Ulrich G. Hofmann
Former Research Associate
Research Interests
HUMAN-MACHINE-INTERFACING
NEURO-ENGINEERING
Goal: Bridging the gap between experimental and simulation approaches for the neuro- and medical sciences.
• Novel high-performance and realtime data acquisition systems for many channels (and neurons).
• Realtime visualization, analysis and data mining in huge neuronal data volumes.
• Modelling of big realistic neuron networks.
CV
2008 Professor, University of Lübeck
2008 Call for a professorate in Biomedical Engineering/Neural Engineering, Reykjavik University, Iceland
2007 Co-Founder of "pro-MedTec GmbH", Lübeck, medical robotics
2005/06 Co-Author "Graduate School Lübeck", DFG-Exzellenzinitiative
2003 Habilitation in Computer Science
1999-2000 Member of the Board of Directors of BioTuL AG, München, Germany
since 1999 Research Associate, University of Lübeck
1997-1998 Postdoctoral Scholar, Feodor-Lynen-Fellow, Division of Biology, California Institute of Technology, Pasadena, CA. "Technology for multisite neuronal recordings"
1996 Research Associate, HCM-Fellow, Institutionen för Fysikalisk Kemi, Åbo Akademi, Turku, Finland. "Ultra-microscopy and surface functionalization of semiconducors"
1993-1996 Research Assistant; Physics Department, Technische Universität München.
Biosensors, ultra-microscopy, ultra-thin films, bio-functionalization, cell culture
1993-1994 Co-founder and part-time manager of the scientific services company MiNT, München
1992-1993 Graduation in Physics, Diploma. Technische Universität München.
Thesis: " Polymerizable diacetylene lipids on the air/water interface"
1987-1992 Undergraduate studies in Technical Physics, Technische Universität München. Specializing in medical electronics and medical radiological physics.
1985-1987 Officer track in the German Army medical service
1985 High School Graduation
2009
Development of Real-Time EEG Application on an Ultra-Low-Power DSP, in International Symposium on Code Generation and Optimization (CGO) -ODES: Workshop on Optimizations for DSP and Embedded Systems , Seattle , 2009. pp. 1-6.
File: | EEG_DWT.pdf |
Bibtex: | @INPROCEEDINGS{EEG_DWT, author = {S. Cirit and J. Penders and M. Ashouei and J. Hulzink and M. de Nil and J. Huisken and U. G. Hofmann}, title = {Development of Real-Time EEG Application on an Ultra-Low-Power DSP}, booktitle = {International Symposium on Code Generation and Optimization (CGO) -ODES: Workshop on Optimizations for DSP and Embedded Systems}, year = {2009}, address = {Seattle} } |
A Sensor for the Non-invasive Determination of Hemoglobin in Sampling Tubes, in IFMBE Proceedings of the World Congress on Medical Physics and Biomedical Engineering , Springer, 2009.
2008
Striatal microstimulation in awake animals depends on NMDA receptor activity, Biomed. Technik / Biomedical Engineering , vol. 53, no. Supp 1, pp. 241-243, 2008.
When Items Become Victims: Brand Memory in Violent and Nonviolent Games, in ICEC 2008 - 7th International Conference on Entertainment Computing , Pittsburgh: Springer, 2008.
Towards a capacitively coupled electrocardiography system for car seat integration, in ECIFMBE 2008- IFMBE Proceedings , Sloten, J. Vander and Verdonck, P. and Nyssen, M. and Haueisen, J., Eds. Antwerp: IFMBE Proceedings ISSN, 2008. pp. 1217-1221.
Hardware-in-the-loop testbed for closed-loop brain stimulators, in ECIFMBE 2008- IFMBE Proceedings , Sloten, J. Vander and Verdonck, P. and Nyssen, M. and Haueisen, J., Eds. Antwerp: IFMBE Proceedings ISSN , 2008. pp. 1128-1132.
Online-Classification of Capnographic Curves Using Artificial Neural Networks, in ECIFMBE 2008- IFMBE Proceedings , Sloten, J. Vander and Verdonck, P. and Nyssen, M. and Haueisen, J., Eds. Antwerp: IFMBE Proceedings ISSN , 2008. pp. 1096-1099.
A new integrated optical and electrophysiological sensor, Biomed. Technik / Biomedical Engineering , vol. 53, no. Supp 1, pp. 126-128, 2008.
Local Region Descriptors for Active Contours., IEEE Trans. Image Proc. , vol. 17, no. 12, 2008.
Bolus Harmonic Imaging zur automatischen Erkennung ischämiebedingter Perfusionsdefizite im Gehirn, Ultraschall in der Medizin , vol. 29, pp. --, 2008.
DOI: | 10.1055/s-2008-1027190 |
File: | Maciak2008.pdf |
Bibtex: | @ARTICLE{Maciak2008, author = {Maciak, A. and Seidel, G. and Meyer-Wiethe, K. and Kier, C. and Hofmann, U.G.}, title = {Bolus Harmonic Imaging zur automatischen Erkennung ischämiebedingter Perfusionsdefizite im Gehirn}, journal = {Ultraschall in der Medizin}, year = {2008}, volume = {29}, pages = {--}, abstract = {Zusammenfassung Ziel: Die Diagnose zerebrovaskulärer Erkrankungen stützt sich zunehmend auf den Einsatz ultraschallbasierter Verfahren. Das kontrastmittelgestützte, transkranielle Bolus Harmonic Imaging (BHI) hat hierbei einen hohen Stellenwert. Die Auswertung der aufgezeichneten Bildsequenz erfolgt durch geübte Ärzte jedoch manuell und ist somit zeitaufwendig. Das Ziel der hier beschriebenen drei Verfahren ist die sichere, vollautomatische Erkennung von Perfusionsdefekten des Gehirns. Material und Methoden: Mit dem BHI werden Ultraschallbildsequenzen aufgezeichnet, die die Kontrastmitteldynamik im Gehirn wiedergeben. Diese Bilder werden mit drei verschiedenen Verfahren automatisch ausgewertet. Zum einen wird ein regelbasiertes System beschrieben, welches aus den aufgezeichneten Ultraschallbildern Parameterbilder extrahiert und diese mithilfe von Expertenwissen nach perfundierten und minderperfundierten Gehirnarealen klassifiziert. Zum zweiten erfolgt die Klassifikation der Gehirngebiete unüberwacht mit dem K-Means-Verfahren. Hierzu wird jedes der Parameterbilder als eine Dimension des zu klassifizierenden Merkmalsraums betrachtet, sodass eine unüberwachte Segmentierung der minderperfundierten Gehirnbereiche möglich ist. Drittens wird die gesamte Bildsequenz anhand der Kontrastmitteldynamik pixelweise klassifiziert. Hierbei kann darauf verzichtet werden, Parameterbilder extrahieren zu müssen. In allen drei Fällen ist es im Anschluss notwendig, die beim HI auftretenden Streifenartefakte automatisch zu erkennen. Abschließend wird ein Aussagenbild generiert, in dem die gefundenen Minderperfusionen markiert sind. Ergebnisse: Die drei Verfahren wurden auf einem 26 Patienten umfassenden Kollektiv klinisch validiert. Hierbei hat sich herausgestellt, dass insbesondere die Segmentierung anhand der Kontrastmitteldynamik dazu geeignet ist, Minderperfusionen automatisch zu erkennen. Es konnte auf diesem Patientenkollektiv eine Sensitivität von 100 % bei einer Spezifität von 100 % erreicht werden. Schlussfolgerungen: Alle drei Verfahren erscheinen geeignet, ischämische Gehirngebiete zu erkennen. Hierbei liefert die Klassifikation von Gehirngebieten nach der Kontrastmitteldynamik die besten Ergebnisse, da sie robust gegenüber Rauschen ist. Zudem ist es das schnellste Verfahren, da die Extraktion von Parameterbildern entfällt. Es ist notwendig, die Sensitivität und Spezifität auf einem größeren Patientenkollektiv zu validieren. Eine sichere, vollautomatische Erkennung von Perfusionsdefekten direkt am Patientenbett scheint somit möglich zu sein. Abstract Purpose: The diagnosis of ischemic stroke relies increasingly on the usage of ultrasound-based methods. One of the recent methods is the transcranial, contrast agent-based Bolus Harmonic Imaging (BHI) method. The captured image sequence is manually examined by clinical experts thus resulting in a time-consuming procedure. The purpose of this study is to evaluate three different methods to analyze BHI image sequences automatically for the detection of ischemic brain tissue. Materials and Method: BHI captures an image sequence that provides information on the dynamic behavior of the ultrasound contrast agents. This image sequence is analyzed using three different procedures. First a system relying on expert knowledge is used to determine perfusion defects. This procedure requires parametric images, which are previously extracted from the image sequence. The parameter images are then categorized by an unsupervised classification method in well-perfused and ischemic tissue by regarding the parametric images as features describing the perfusion. Thirdly, the whole image sequence can be interpreted as a pixel-by-pixel behavior out of contrast agents. The dynamic curve of each pixel can be automatically classified as perfused and ischemic tissue by the K-Means method without extracting parametric images. In all three cases a closing step is necessary for the accurate interpretation of the results. Transcranial ultrasound imaging produces typical stripe artifacts that have to be detected and eliminated. A result image is then created and provides a conclusion about perfusion reduction in brain tissue. Results: All three methods have been validated on the basis of 26 patients by clinical experts. The segmentation on the contrast agent kinetics has proven to be most effective. According to our patient database, it provides the highest detection accuracy, resulting in a sensitivity of 100 % and a specificity of 100 %. Conclusion: The presented methods seem to be adequate for detecting ischemic brain tissue. The classification of contrast agent kinetics provides the best results and has further advantages. It is robust with respect to noise and the calculation is fast because the extraction of parametric images is omitted. The very high sensitivity and specificity must be validated in a larger patient population. Reliable and automated detection of perfusion defects at the bedside seems to be possible.}, booktitle = {Automatic Detection of Perfusion Deficits with Bolus Harmonic Imaging}, doi = {10.1055/s-2008-1027190}, refid = {101055S20081027190} } |
Local Region Descriptors for Active Contours Evolutions, IEEE Transactions on Image Processing , vol. 17, no. 12, pp. 2275-2288, 2008.
File: | cristina-TIP2008.pdf |
Bibtex: | @ARTICLE{DaroltiTIP08, author = {Cristina Darolti and Christoph Bodensteiner and Alfred Mertins and Ulrich G. Hofmann}, title = {Local Region Descriptors for Active Contours Evolutions}, journal = {IEEE Transactions on Image Processing}, volume = {17}, number = {12}, pages={2275-2288}, year = {2008} } |
2007
A design study on a multisensory cerebral monitor, in BMT 2007 , Aachen: de Gruyter, 2007.
Segmenting the substantia nigra in ultrasound images for early diagnosis of Parkinson's disease, International Journal of Computer Assisted Radiology and Surgery , vol. 2, no. S1, pp. S83--S85, 2007.
DOI: | 10.1007/s11548-007-0086-4 |
File: | Kier2007Presentation.pdf |
Bibtex: | @ARTICLE{Kier2007, author = {Christian Kier and Christina Cyrus and Günter Seidel and Ulrich G. Hofmann and Til Aach}, title = {Segmenting the substantia nigra in ultrasound images for early diagnosis of Parkinson's disease}, journal = {International Journal of Computer Assisted Radiology and Surgery}, year = {2007}, volume = {2}, pages = {S83--S85}, number = {S1}, month = {June}, doi = {10.1007/s11548-007-0086-4}, keywords = {parkinson} } |
Robuste Ermittlung parametrischer Bilder für die Ultraschall-Perfusionsbildgebung basierend auf einem Modell der Boluskinetik von Kontrastmitteln, Biomedizinische Technik. Ergänzungsband. , vol. 52, pp. Session A2, 2007.
File: | Maciak2007b.pdf |
Bibtex: | @ARTICLE{Maciak2007b, author = {Adam Maciak and Christian Kier and G{\"u}nter Seidel and Karsten Meyer-Wiethe and Ulrich Hofmann and Til Aach}, title = {Robuste Ermittlung parametrischer Bilder für die Ultraschall-Perfusionsbildgebung basierend auf einem Modell der Boluskinetik von Kontrastmitteln}, journal = {Biomedizinische Technik. Ergänzungsband.}, year = {2007}, volume = {52}, pages = {Session A2}, address = {Berlin}, issn = {0939-4990}, keywords = {perfuscope} } |
A Fast Level-Set Method for Accurate Tracking of Articulated Objectswith An Edge-Based Binary Speed Term, in Advanced Concepts for Intelligent Vision Systems , Jacques Blanc-Talon, Wilfried Philips, Dan Popescu und Paul Scheunders, Eds. Springer, 2007. pp. 828-839.
File: | DaroltiACVIS07.pdf |
Bibtex: | @INPROCEEDINGS{DaroltiACIVS, author = {Cristina Darolti and Alfred Mertins and Ulrich G. Hofmann}, title = {A Fast Level-Set Method for Accurate Tracking of Articulated Objectswith An Edge-Based Binary Speed Term}, booktitle = {Advanced Concepts for Intelligent Vision Systems}, year = {2007}, editor = {Jacques Blanc-Talon, Wilfried Philips, Dan Popescu und Paul Scheunders}, number = {4678}, series = {Lecture Notes in Computer Science}, pages = {828-839}, month = {August}, publisher = {Springer}, owner = {darolti}, timestamp = {2007.07.13} } |
Measurement of Surgical Motion with a Marker Free Computer Vision Based System, International Journal of Computer Assisted Radiology and Surgery , vol. 2, S1, pp. S213, 2007.
File: | Darolti_CARS07.pdf |
Bibtex: | @ARTICLE{DaroltiCars, author = {Cristina Darolti and Ralf Bouchard and Stefan Farke and Alexandru P. Condurache and Ulrich Hofmann}, title = {Measurement of Surgical Motion with a Marker Free Computer Vision Based System}, journal = {International Journal of Computer Assisted Radiology and Surgery}, year = {2007}, volume = {2, S1}, pages = {S213}, owner = {darolti}, timestamp = {2007.07.13} } |
Navigated intraoperative ultrasound imaging system, in BMT 2007 , Aachen: de Gruyter, 2007.
Electrical High Frequency Stimulation Induces GABA Outflow in Freely Moving Rats, J. Neurosci. Methods , vol. 159, no. 2, pp. 286-290, 2007.
Detecting Stripe Artifacts in Ultrasound Images, Journal of Digital Imaging , 2007.
DOI: | 10.1007/s10278-007-9049-0 |
File: | Maciak2007a.pdf |
Bibtex: | @ARTICLE{Maciak2007a, author = {A. Maciak and C. Kier and G. Seidel and K. Meyer-Wiethe and U. G. Hofmann}, title = {Detecting Stripe Artifacts in Ultrasound Images}, journal = {Journal of Digital Imaging}, year = {2007}, doi = {10.1007/s10278-007-9049-0}, url = {http://www.springerlink.com/content/rm058658xpv37ph2/?p=fbae785cac25420b93dd3c1a6b1428a9&pi=0} } |
Automatic measuring of quality criteria for heart valves, in Medical Imaging 2007: Image Processing , San Diego, CA: SPIE, 2007.
File: | condurache_hvalve_mi2007.pdf |
Bibtex: | @InProceedings{Condurache07, title = {Automatic measuring of quality criteria for heart valves}, booktitle = {Medical Imaging 2007: Image Processing}, author = {A. P. Condurache and T. Hahn and M. Scharfschwerdt and M. Misfeld and U. G. Hofmann and T. Aach}, publisher = {SPIE}, address = {San Diego, CA}, month ={February}, year = {2007}, } |
A simple microelectrode bundle for deep brain recordings, in 3rd Int'l Conference on Neural Engineering , Akay, Metin, Eds. Hawaii, USA: IEEE, 2007.
In vivo implant mechanics of single-shaft microelectrodes in peripheral nervous tissue, in 3rd Int'l Conference on Neural Engineering , Akay, Metin, Eds. Hawaii, USA: IEEE, 2007.
2006
A novel high channel-count system for acute multi-site neuronal recordings, 2006.
File: | TBME_00583-2004.R2_preprint.pdf |
Bibtex: | @InProceedings{ Hofmann06, title = {A novel high channel-count system for acute multi-site neuronal recordings}, author = {U.G. Hofmann and A. Folkers and F. M{\"o}sch and T. Malina and K.M.L. Menne and M.G. Kindlundh and U. Thomas and D. Hoehl and G. Biella and E. De Schutter and P. Fagerstedt and K. Yoshida and W. Jensen and P. Norlin and M. de Curtis}, year = {2006} } |
Atrial Near-Field and Ventricular Far-Field Analysis by Automated Signal Processing at Rest and During Exercise., .... Wiley, 2006.
File: | Eberhardt_et_al_ANE_2006_01.pdf |
Bibtex: | @Book{EberhardtArtrial2006, title = {Atrial Near-Field and Ventricular Far-Field Analysis by Automated Signal Processing at Rest and During Exercise}, publisher = {Wiley}, series = {Ann Noninvasive Electrocardiol.}, year = {2006}, author = {Eberhardt, F. and Bonnemeier, H. and Lipphardt, M. and Hofmann, U.G. and Schunkert, H. and Wiegand, U.}, volume = {11, Issue 2}, month = { März} } |
Implant Mechanics of ACREO Silicon Electrodes in Rat Cerebral Cortex, IEEE Transactions on Bio-Medical Engineering , 2006.
File: | 53tbme05-jensen-proof-wj_01.pdf |
Bibtex: | @Article{Jensen06, author = {Jensen, W. and Yoshida, K. and Hofmann, U.G.}, title = {Implant Mechanics of ACREO Silicon Electrodes in Rat Cerebral Cortex}, journal = {IEEE Transactions on Bio-Medical Engineering}, year = {2006}, month = { Januar}, } |