TY - CHAP A1 - Scholl, Ingrid A1 - Palm, Christoph A1 - Sovakar, Abhijit A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus ED - Arnolds, B. ED - Mueller, H. ED - Saupe, D. ED - Tolxdorff, Thomas T1 - Quantitative Analyse der Stimmlippen T2 - 5. Workshop Digitale Bildverarbeitung in der Medizin, Universität Freiburg, 10.-11. März 1997 KW - Konturverfolgung KW - Snakes KW - Farbanalyse KW - Dichromatisches Reflexionsmodell KW - Farbkonstanz KW - Laryngoskopie Y1 - 1997 UR - https://pdfs.semanticscholar.org/9a0c/9e7dc883ccf6e8a8a686c28422238adb5f35.pdf SP - 81 EP - 86 ER - TY - CHAP A1 - Palm, Christoph A1 - Scholl, Ingrid A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus ED - Lehmann, Thomas M. ED - Metzler, V. ED - Spitzer, Klaus ED - Tolxdorff, Thomas T1 - Quantitative Farbmessung in laryngoskopischen Bildern T2 - Bildverarbeitung für die Medizin N2 - Quantitative Farbmessungen sollen die Diagnostik laryngealer Erkrankungen unterstützen. Dabei wird der Farbeindruck nicht nur durch die Reflexionseigenschaften des Gewebes sondern auch durch die Farbe der verwendeten Lichtquelle beeinflußt. Der hier vorgestellte Farbkonstanz-Algorithmus basiert auf dem dichromatischen Reflexionsmodell und liefert eine pixelweise Trennung des Farbbildes in seine beiden Faxbanteile. Die Körperfarbe entspricht dabei der gewebespezifischen Reflexion, die Oberfächenfarbe der Strahlung der Lichtquelle. KW - Farbkonstanz KW - quantitative Farbmessung KW - dichromatisches Reflexionsmodell KW - Laryngoskopie Y1 - 1998 U6 - https://doi.org/10.1007/978-3-642-58775-7_81 SP - 412 EP - 416 PB - Springer CY - Berlin ER - TY - CHAP A1 - Palm, Christoph A1 - Scholl, Ingrid A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus ED - Greiser, E. ED - Wischnewsky, M. T1 - Nutzung eines Farbkonstanz-Algorithmus zur Entfernung von Glanzlichtern in laryngoskopischen Bildern T2 - Methoden der Medizinischen Informatik, Biometrie und Epidemiologie in der modernen Informationsgesellschaft N2 - 1 Einführung Funktionelle und organische Störungen im Larynx beeinträchtigen die Ausdrucksfähigkeit des Menschen. Zur Diagnostik und Verlaufkontrolle werden die Stimmlippen im Larynx mit Hilfe der Video-Laryngoskopie aufgenommen. Zur optimalen Farbmessung wird dazu an das Lupenendoskop eine 3-Chip-CCD-Kamera angeschlossen, die eine unabhängige Aufnahme der drei Farbkanäle erlaubt. Die bisherige subjektive Befundung ist von der Erfahrung des Untersuchers abhängig und läßt nur eine grobe Klassifikation der Krankheitsbilder zu. Zur Objektivierung werden daher quantitative Parameter für Farbe, Textur und Schwingung entwickelt. Neben dem Einfluß der wechselnden Lichtquellenfarbe auf den Farbeindruck ist die Sekretauflage auf den Stimmlippen ein Problem bei der Farb-und Texturanalyse. Sie kann zu ausgedehnten Glanzlichtern führen und so weite Bereiche der Stimmlippen für die Farb-und Texturanalyse unbrauchbar machen. Dieser Beitrag stellt einen Farbkonstanz-Algorithmus vor, der unabhängig von der Lichtquelle quantitative Farbwerte des Gewebes liefert und die Glanzlichtdetektion und -elimination ermöglicht. 2 Methodik Ziel des Farbkonstanz-Algorithmus ist die Trennung von Lichtquellen-und Gewebefarbe. Unter Verwendung des dichromatischen Reflexionsmodells [1] kann die Oberflächenreflexion mit der Farbe der Lichtquelle und die Körperreflexion mit der Gewebefarbe identifiziert werden. Der Farbeindruck entsteht aus der Linearkombination beider Farbkomponenten. Ihre Gewichtung ist von der Aufnahmegeometrie abhängig, insbesondere vom Winkel zwischen Oberflächennormalen und dem Positionsvektor der Lichtquelle. In einem zweistufigen Verfahren wird zunächst die Lichtquellenfarbe geschätzt, dann die Gewebefarbe ermittelt. Hieraus können beide Farbanteile durch die Berechnung der Gewichtsfaktoren pixelweise getrennt werden. KW - Farbkonstanz KW - Glanzlichtelimination KW - medizinische Bildverarbeitung KW - dichromatisches Reflexionsmodell Y1 - 1998 SN - 9783820813357 SP - 300 EP - 303 PB - MMV Medien und Medizin CY - München ER - TY - GEN ED - Lehmann, Thomas M. ED - Palm, Christoph ED - Spitzer, Klaus ED - Tolxdorff, Thomas T1 - Advances in Quantitative Laryngoscopy, Voice and Speech Research, Procs. 3rd International Workshop, RWTH Aachen Y1 - 1998 CY - Aachen ER - TY - CHAP A1 - Palm, Christoph A1 - Pelkmann, Annegret A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus T1 - Distortion Correction of Laryngoscopic Images T2 - Advances in quantitative laryngoscopy, voice and speech research, Proceedings of the 3rd international workshop Aachen, RWTH N2 - Laryngoscopic images of the vocal tract are used for diagnostic purposes. Quantitative mea-surements like changes of the glottis size or the surface of the vocal cords during an image sequence can be helpful to describe the healing process or to compare the findings of diffe-rent patients. Typically the endoscopic images are circulary symmetric distorted (barrel di-stortion). Therefore measurements of geometric dimensions depend on the object´s position in the image. In this paper an algorithm is presented which allows the computation of the translational invariant "real" object size by correcting the image distortion without using additional calibration of the optical environment. KW - image distortion KW - camera calibration KW - multiple regression analysis Y1 - 1998 UR - https://pdfs.semanticscholar.org/e9d8/eb27af24bd79f482821441c2bf0eee7b3fe6.pdf?_ga=2.183754286.985176231.1591560247-1467258391.1581026068 SP - 117 EP - 125 ER - TY - CHAP A1 - Palm, Christoph A1 - Neuschaefer-Rube, C. A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus ED - Evers, H. ED - Glombitza, G. ED - Lehmann, Thomas M. ED - Meinzer, H.-P. T1 - Wissensbasierte Bewegungskompensation in aktiven Konturmodellen T2 - Bildverarbeitung für die Medizin N2 - Zur Analyse von Lippenbewegungsabläufen wird ein aktives Konturmodell eingesetzt. Probleme bereitet die hohe Sprechgeschwindigkeit, die in star ken Objektverschiebungen result iert und bislang nicht durch eine alleinige Konturanpassung kompensiert werden kann. In diesem Beitrag werden die klassischen aktiven Konturmodelle um eine Vorjustierung der Grobkonturen erweitert, die eine energiebasierte Konturanpassung erst möglich macht. Die Schätzung der Verschiebung zur Vorjustierung basiert auf dem Gradientenbild und einem prädikatenlogisch formulierten Regelwerk, das Annahmen und Nebenbedingungen als Wissensbasis enthält. Mit Hilfe dieser Erweiterungen ist eine automatisierte Konturverfolgung der Lippen möglich. KW - Aktives Konturmodell KW - Pradikatenlogik KW - Bewegungsschatzung Y1 - 1999 U6 - https://doi.org/10.1007/978-3-642-60125-5_2 SP - 8 EP - 12 PB - Springer CY - Berlin ER - TY - CHAP A1 - Palm, Christoph A1 - Metzler, V. A1 - Moham, B. A1 - Dieker, O. A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus ED - Evers, H. ED - Glombitza, G. ED - Lehmann, Thomas M. ED - Meinzer, H.-P. T1 - Co-Occurrence Matrizen zur Texturklassifikation in Vektorbildern T2 - Bildverarbeitung für die Medizin N2 - Statistische Eigenschaften natürlicher Grauwerttexturen werden mit Co-Occurrence Matrizen, basierend auf der Grauwertstatistik zweiter Ordnung, modelliert. Die Matrix gibt dann die apriori Wahrscheinlichkeiten aller Grauwertpaare an. Da in der medizinischen Bildverarbeitung verstärkt Multispektralbilder ausgewertet werden, wird das bekannte Konzept hier auf beliebige Vektorbilder erweitert. Dadurch kann bei der Texturklassifikation die zur Verfügung stehende Information vollständig genutzt werden. Insbesondere zur Detektion von Farbtexturen ist dieser Ansatz geeignet, da Wertepaare unterschiedlicher Spektralebenen ausgewertet werden können. Ebenso kann die Methode auch bei der Multiskalendekomposition von Intensitätsbildern zur Verbesserung der Texturerkennung beitragen. Die in den Matrizen entstehenden Muster lassen dann über die Extraktion geeigneter Texturdeskriptoren Rückschlüsse auf die Texturen des Bildes zu. KW - Texturerkennung KW - Vektorbilder KW - Multispektralbilder KW - Multiskalenbilder KW - Klassifikation Y1 - 1999 U6 - https://doi.org/10.1007/978-3-642-60125-5_69 SP - 367 EP - 371 PB - Springer CY - Berlin ER - TY - CHAP A1 - Palm, Christoph A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus T1 - Bestimmung der Lichtquellenfarbe bei der Endoskopie mikrotexturierter Oberflächen des Kehlkopfes T2 - 5. Workshop Farbbildverarbeitung, Ilmenau, 1999 N2 - Zur Unterstützung der Diagnose von Stimmlippenerkrankungen werden innerhalb des Forschungsprojektes Quantitative Digitale Laryngoskopie objektive Parameter zur Beschreibung der Bewegung, der Farbe sowie der Form der Stimmlippen entwickelt und klinisch evaluiert. Während die Bewegungsanalyse Aufschluß über funktionelle Stimmstörungen gibt, beschreiben Parameter der Farb- und Formanalyse morphologische Veränderungen des Stimmlippengewebes. In diesem Beitrag werden die Methoden und bisherigen Ergebnisse zur Bewegungs- und Farbanalyse vorgestellt. Die Bewegungsanalyse wurde mit einem erweiterten Konturmodell (Snakes) durchgeführt. Aufgrund des modifizierten Konturmodells konnten die Konturen der Stimmlippen automatisch über die gesmate Bildsequenz zuverlässig detektiert werden. Die Vermssung der Konturen liefert neue quantitative Parameter zur Befundung von laryngoskopischen Stimmlippenaufnahmen. Um die Farbeigenschaften der Stimmlippen zu bestimmen, wurde ausgehend vom RGB-Bild die Objektfarbe unabhängig von der Farbe der Lichtquelle durch Verwendung von Clusterverfahren und der Viertelkreisanalyse berechnet. Mit dieser Farbanalyse konnte die Farbe der Lichtquelle ermittelt und das beleuchtungsunabhängige Farbbild berechnet werden. Die Quanitifizierung der Rötung der Stimmlippen ist z.B. ein entscheidendes Kriterium zur Diagnostik der akuten Laryngitis. KW - Konturverfolgung KW - Snakes KW - Dichromatisches Reflexionsmodell KW - Farbkonstanz KW - Laryngoskopie Y1 - 1999 UR - http://www.germancolorgroup.de/html/Vortr_99_pdf/01_Palm.pdf SP - 3 EP - 10 ER - TY - JOUR A1 - Hartmann, Robin A1 - Weiherer, Maximilian A1 - Schiltz, Daniel A1 - Seitz, Stephan A1 - Lotter, Luisa A1 - Anker, Alexandra A1 - Palm, Christoph A1 - Prantl, Lukas A1 - Brébant, Vanessa T1 - A Novel Method of Outcome Assessment in Breast Reconstruction Surgery: Comparison of Autologous and Alloplastic Techniques Using Three-Dimensional Surface Imaging JF - Aesthetic Plastic Surgery N2 - Background Breast reconstruction is an important coping tool for patients undergoing a mastectomy. There are numerous surgical techniques in breast reconstruction surgery (BRS). Regardless of the technique used, creating a symmetric outcome is crucial for patients and plastic surgeons. Three-dimensional surface imaging enables surgeons and patients to assess the outcome’s symmetry in BRS. To discriminate between autologous and alloplastic techniques, we analyzed both techniques using objective optical computerized symmetry analysis. Software was developed that enables clinicians to assess optical breast symmetry using three-dimensional surface imaging. Methods Twenty-seven patients who had undergone autologous (n = 12) or alloplastic (n = 15) BRS received three-dimensional surface imaging. Anthropomorphic data were collected digitally using semiautomatic measurements and automatic measurements. Automatic measurements were taken using the newly developed software. To quantify symmetry, a Symmetry Index is proposed. Results Statistical analysis revealed that there is no dif- ference in the outcome symmetry between the two groups (t test for independent samples; p = 0.48, two-tailed). Conclusion This study’s findings provide a foundation for qualitative symmetry assessment in BRS using automatized digital anthropometry. In the present trial, no difference in the outcomes’ optical symmetry was detected between autologous and alloplastic approaches. KW - Breast reconstruction KW - Breast symmetry KW - Digital anthropometry KW - Mammoplastik KW - Dreidimensionale Bildverarbeitung KW - Autogene Transplantation KW - Alloplastik Y1 - 2020 U6 - https://doi.org/10.1007/s00266-020-01749-4 VL - 44 SP - 1980 EP - 1987 PB - Springer CY - Heidelberg ER - TY - CHAP A1 - Palm, Christoph A1 - Keysers, Daniel A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus T1 - Gabor Filtering of Complex Hue/Saturation Images for Color Texture Classification T2 - Proceedings of the 5th Joint Conference on Information Science (JCIS) 2, The Association for Intelligent Machinery, Atlantic City, NJ, 2000 N2 - Objective: Complex hue/saturation images as a new approach for color texture classification using Gabor filters are introduced and compared with common techniques. Method: The interpretation of hue and saturationas polar coordinates allows direct use of the HSV-colorspace for Fourier transform. This technique is applied for Gabor feature extraction of color textures. In contrast to other color features based on the RGB-colorspace [1] the combination of color bands is done previous to the filtering. Results: The performance of the new HS-featuresis compared with that of RGB based as well as grayscale Gabor features by evaluating the classifi-cation of 30 natural textures. The new HS-featuresshow same results like the best RGB features but allow a more compact representation. On the averagethe color features improve the results of grayscale features. Conclusion: The consideration of the color information enhances the classification of color texture. The choice of colorspace cannot be adjudged finally, but the introduced features suggest the use of the HSV-colorspace with less features than RGB. Y1 - 2000 UR - http://www.keysers.net/daniel/files/JCIS2000_palm.pdf SP - 45 EP - 49 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Bilek, Karin A1 - Hentschel, Bettina T1 - Tumor size is of prognostic value in surgically treated FIGO stage II cervical cancer JF - Gynecologic Oncology N2 - Objectives Tumor size is a well recognized prognostic factor in early stage cervical carcinoma (CX). However, limited knowledge exists about the value of tumor size in surgically treated CX with extrauterine extension. Methods 245 cases of local advanced CX (FIGO stage IIA and IIB) who received upfront surgery were evaluated regarding tumor size, regarding the prediction of pelvic lymph node involvement and recurrence free and overall survival during a median follow-up time of 54 months (95% CI 45.4–62.6 months). Tumors larger than 4 cm were defined as bulky stage disease. Results Bulky disease was seen in 46.1% (113/245). 60.2% of these patients showed pelvic lymph node involvement, compared to 42.4% (56/132) in non-bulky tumors (p = 0.006; odds ratio: 2.2 [95% CI: 1.3–3.6]). Patients with bulky tumors showed an increase of recurrent disease (40.2% vs. 28.0%; p = 0.045). The relative risk for recurrent disease was 1.97 (95% CI: 1.3–3.0). The 5-year overall survival rate was significantly lower (67.7% [95% CI: 58.2–74.8] vs. 49.5% [95% CI: 36.8–59.1]; p = 0.0015). In multivariate analysis, tumor stage, pelvic lymph node involvement and maximal tumor size were independent prognostic factors. Conclusions The results suggest that tumor size, defining bulky disease as tumors larger than 4 cm, is of prognostic impact also in FIGO stage II cervical carcinomas. A revised FIGO/TNM classification system similar to the subgrouping of stage IB CX is recommended for stage II using a cut-off value of 4 cm as discriminator: stage IIA1 and stage IIB1 for tumors with ≤ 4 cm and IIA2 and IIB2 for tumors > 4 cm (i.e. bulky disease). KW - Gebärmutterhalskrebs KW - Chirurgie KW - Tumorwachstum Y1 - 2007 U6 - https://doi.org/10.1016/j.ygyno.2007.06.026 VL - 107 IS - 2 SP - 310 EP - 315 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Bilek, Karin A1 - Hentschel, Bettina A1 - Richter, Christine E. A1 - Braumann, Ulf Dietrich A1 - Einenkel, Jens T1 - Pattern of invasion is of prognostic value in surgically treated cervical cancer patients JF - Gynecologic Oncology N2 - Objectives: Different patterns of invasion (representing different grades of tumor cell dissociation) are associated with prognostic outcome in cancer. We evaluated the prognostic value of different patterns of invasion (PI) in cervical carcinomas (CX). Methods: Six hundred eleven surgically treated CX (FIGO IB to IIB) were re-evaluated histologically regarding the PI, using a three-level scoring system. Closed PI was defined as cohesive growth with well-delineated (pushing) borders. In finger-like PI the tumor grows in solid cords/trabecles. Highly dissociative growth in small groups or single cells was defined as spray-like PI. Types of PI were correlated to tumor stage, histo-morphologic factors and prognostic outcome. Results: Sixty percent of the tumors showed a spray-like PI, 30% a finger-like PI and only 7.4% were of the closed type. Spray-like PI showed a significant correlation with advanced stage disease, lymphovascular space involvement, poorly differentiated tumors and pelvic lymph node metastases. Spray-like PI was accompanied by a reduced 5-year overall survival when compared to the finger-like and closed PI (68.7% vs. 80.9% vs. 88.5%; P=0.0004). The prognostic impact of the PI disappeared in node-positive patients (P=0.06) but persisted in patients without pelvic lymph node disease (P=0.03). In multivariate analysis, using COX regression model, the PI represented as independent prognostic factor. Conclusions: Spray-like PI (i.e., highest degree of tumor cell dissociation) is associated with advanced tumor stages, increased rate of recurrency and a reduced overall survival. In separate analysis of patients with and without lymph node metastases, the impact of PI persisted only in node-negative cases as a prognostic factor. KW - Gebärmutterhalskrebs KW - Chirurgie KW - Metastase Y1 - 2006 U6 - https://doi.org/10.1016/j.ygyno.2006.05.046 VL - 103 IS - 3 SP - 906 EP - 911 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Hentschel, Bettina A1 - Köhler, U. A1 - Richter, Christine E. A1 - Martin, Rosemarie T1 - CD44-v6 concentrations in carcinoma of the uterine cervix: lack of prognostic significance JF - Archives of Gynecology and Obstetrics N2 - Several kinds of cellular adhesion molecules, like different splicing variants of CD 44, have gained important as prognostic or markers for metastatic disease. Fresh frozen samples from 64 cervical carcinoma (CX) were stored in liquid nitrogen and examined using ELISA-technique, testing the prognostic impact. Normal cervical tissue served as control. CD 44-v6 concentration, was significant elevated in tumor tissue, when compared to the controls (P=0.04). There was no correlation to tumor stage (P=0.61), lymphovascular space involvement (P=0.075) or pelvic lymph node involvement (P=0.81). The CD 44-v6 concentration was not informative regarding recurrence-free and overall survival. Contrary to immunohistochemistry, the quantification of CD 44-v6 using ELISA-technique does not provide any further information. KW - Gebärmutterhalskrebs KW - Antigen CD44 Y1 - 2005 U6 - https://doi.org/10.1007/s00404-005-0039-5 VL - 273 IS - 2 SP - 104 EP - 106 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Nenning, Hans T1 - DNA cytometric analysis of surgically treated squamous cell cancer of the uterine cervix, stage pT1b1-pT2b JF - Analytical and quantitative cytology and histology N2 - Objective: To determine the utility of DNA content and DNA-related variables of proliferative activity regarding prognosis in cervical cancer. Study design: DNA image (ICM) andflow cytometry (FCM) were performed to determine the DNA index (DI), 5c-exceeding rate (5c-ER), S-phase fraction (SPF) and proliferation index (PI) in 163 patients with surgically staged pT1b1-pT2b squamous cell cancer of the uterine cervix and treated with primary radical hysterectomy. ICM was performed on imprint cytology, obtained from fresh tumor tissue, which was also used for FCM. Results were analyzed using the chi2 test and Cox regression analysis for risk of pelvic lymph node involvement, tumor recurrence and recurrence-free survival (RFS). Results: ICM was performed on all 163 and FCM on 133 samples. One-third of the tumors showed DNA aneuploidy. Analysis demonstrated prognostic significance of a DI > or = 1.70, with a (70:30) 2.3-fold risk of recurrence (P=.024) and reduced RFS of 10 months (P=.003) in cases of DI > or = 1.70. A high 5c-ER > 11% was associated with pelvic lymph node involvement and decreased RFS (P < or = .04). Significantly more relapses were found in tumors with SPF > 12% (70.8% vs. 29.2%, P=.007). RFS was markedly reduced in tumors with high SPF (52.3 vs. 61.1 months, P=.011). Low proliferative tumors (PI<25%) were associated with lower stage (P=.036) and increased RFS (61.2 vs. 47.1 months, P=.028). In multivariate analysis of clinicopathologic variables (pT category, nodal status, lymphovascular space involvement) and DNA related variables, pelvic lymph node involvement was the only significant predictor of RFS. In patients with nodal involvement, tumors with DI >1.70 were associated with lessfavorable outcomes. Conclusion: DNA-related variables of cell cycle analysis were valuablefor predicting prognosis in cervical cancer patients. Tumors with DI>1.70, 5c-ER >11% and high proliferative activity (SPF>12%, PI>25%) represent a subgroup with a poor prognosis. KW - Gebärmutterhals KW - squamöser Krebs KW - Cytometrie KW - Chirurgie Y1 - 2002 VL - 24 IS - 1 SP - 23 EP - 29 ER - TY - CHAP A1 - Horn, Lars-Christian A1 - Pippig, S. A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Köhler, U. A1 - Hentschel, Bettina A1 - Martin, Rosemarie T1 - Tumorassoziierte Proteolyse beim Zervixkarzinom BT - Vortrag T2 - 87. Tagung der Deutschen Gesellschaft für Pathologie, 14. Juni 2003 KW - Gebärmutterhalskrebs KW - Chirurgie KW - Tumorassoziierte Proteolyse KW - Immuncytochemie KW - Zelladhäsion Y1 - 2003 ER - TY - CHAP A1 - Höh, H. A1 - Raptis, Georgios T1 - Applications of the Erbium: YAG Laser in Ophthalmology - Cataracta-, Glaukoma-, Eyelid-Surgery and pars plana Vitrectomy BT - Symposium on Cataract, IOL, and Refractive Surgery. Boston, 20.05.2000 und 22.05.2000 N2 - Recent developments in lasers have provided us the possibility of laser ocular surgery. The xenon, argon, neodymium:YAG and dye lasers have been successfully used in out-patient clinics. The excimer laser has been attracting researchers' interest in the new application of laser to cornea and lens. The erbium:YAG laser emits a 2.94-microns beam that can ablate the transparent ocular tissues such as lenses and corneas. The author has applied this laser to the cornea, lens, vitreous and other ocular tissues. The erbium:YAG laser beam was directed through a 1.5-meter-long, 200-microns-diameter fiberoptic guide. The radiant energy measured about 50 mJ at the end of the probe. The laser was emitted as a 400-microsecond pulse. Freshly enucleated rabbit eyes were used in this study. Laser burns were applied to the tissue surface at various energy settings. At minimal power, the tissues were coagulated by the erbium:YAG laser application. At a power of more than 636-954 mJ/mm2, tissue began to evaporate; the tissue loss was observed under a surgical light microscope. Corneal photoablation, lens ablation, iridotomy, trabeculotomy, cutting of the vitreous and retinal ablation were easily performed. Like the excimer laser, the erbium:YAG laser is a potential tool for ocular surgery. KW - Augenchirurgie KW - YAG-Laser KW - Erbium-Laser Y1 - 2000 ER - TY - JOUR A1 - Chaloupka, I. A1 - Raptis, Georgios A1 - Zach, A. A1 - Brändlin, K. A1 - Meier-Ewert, H. T1 - Rolle der quantitativen CMV-DNA-Bestimmungen in der Diagnostik und Therapie der Cytomegalovirusinfektion bei immunsupprimierten Patienten BT - Vortrag JF - Jahrestagung der Gesellschaft für Virologie in Wien, April 2000 KW - Cytomegalie-Virus KW - Diagnose KW - Immunsuppresion Y1 - 2000 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Pippig, S. A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Köhler, U. A1 - Hentschel, Bettina A1 - Martin, Rosemarie T1 - Clinical relevance of urokinase-type plasminogen activator and its inhibitor type-1 (PAI-1) in squamous cell carcinoma of the uterine cervix JF - Australian and New Zealand Journal of Obstetrics and Gynaecology N2 - Objective The expression of uPA and PAI‐1 as parameters of tumour‐associated proteolysis has been implicated in the process of tumour cell invasion and the metastatic process. However, there is limited information on the impact of these parameters in cervical carcinoma. Methods Quantitative levels for uPA (n = 114) and PAI‐1 (n = 103) were researched in operatively treated, surgically staged squamous cell cancer of the uterine cervix, using an ELISA‐technique. Results were assessed regarding their impact in predicting pelvic lymph nodes metastases, tumour recurrence rate and recurrence free survival (RFS) using uni‐ and multivariate analysis. Results Median levels of both parameters were significantly higher in tumour tissue than in normal cervical tissue (p < 0.001). Detection of uPA gave no useful prognostic information. PAI‐1 concentration showed a positive correlation with advanced tumour stage (p = 0.008), but no significant correlation with nodal status (pN0: 2.6 vs. pN1: 4.0 ng/mg protein; p = 0.092). Using a cut‐off level of 2.4 ng/mg protein, patients with elevated PAI‐1 levels demonstrated reduced RFS (45.9 versus 52.9 months; p = 0.1). Multivariate analysis, including nodal status, tumour stage, lymphovascular space involvement and grading failed to demonstrate any prognostic impact of uPA and PAI‐1. Conclusions The results indicate, that PAI‐1 expression is of some prognostic impact in cervical cancer, indicating an association of elevated PAI levels with local tumour progression and reduced recurrence‐free survival. KW - Plasminogen human-Aktivator KW - Urokinase KW - squamöser Krebs KW - Gebärmutterhals Y1 - 2004 U6 - https://doi.org/10.1111/j.0004-8666.2002.00385.x VL - 42 IS - 4 SP - 385 EP - 388 ER - TY - JOUR A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Geßner, W. A1 - Roschlau, U. A1 - Dressel, K. A1 - Bilek, Karin A1 - Horn, Lars-Christian T1 - Epidemiologie und formale Pathogenese des Zervixkarzinoms JF - Zentralblatt für Gynäkologie T2 - Epidemiology and pathogenesis of cervical cancer KW - Gebärmutterhalskrebs KW - Epidemiologie KW - Pathogenese Y1 - 2001 VL - 123 IS - 4 SP - 198 EP - 205 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Fischer, Uta A1 - Hanel, C. A1 - Kuhn, H. A1 - Raptis, Georgios A1 - Bilek, Karin T1 - p53 in surgically treated and pathologically staged cervical cancer BT - correlation with local tumor progression, but not with lymphatic spread JF - Pathology - Research and Practice KW - Gebärmutterhalskrebs KW - Tumorsuppressor-Gen KW - Chirurgie KW - Histopathologie Y1 - 2001 VL - 197 IS - 9 SP - 605 EP - 609 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Bilek, Karin T1 - Impact of tumorload in surgically treated, histologically staged early cervical cancer: Multivariate analysis of 568 patients JF - International Journal of Gynecology & Obstetrics KW - Gebärmutterhalskrebs KW - Chirurgie KW - Tumorklasifikation Y1 - 2000 VL - 70 IS - Suppl. 1 SP - 20 EP - 21 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Bilek, Karin T1 - p53-tumorsuppressor gene in surgically treated histologically staged early cervical cancer JF - International Journal of Gynecology & Obstetrics KW - Tumorsuppressor-Gen KW - Chirurgie KW - Histopathologie KW - Gebärmutterhalskrebs Y1 - 2000 VL - 70 IS - Suppl. 1 SP - 112 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Martin, Rosemarie T1 - Tumorassoziierte Proteolyse, p53-Immunhistochemie und Zelladhäsion bei primär operierten Zervixkarzinomen JF - Geburtshilfe und Frauenheilkunde KW - Tumorassoziierte Proteolyse KW - Immuncytochemie KW - Zelladhäsion KW - Gebärmutterhalskrebs Y1 - 2000 VL - 60 IS - Suppl. 1 SP - 200 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta A1 - Bilek, Karin T1 - Standardised handling of hysterectomy specimen in cervical cancer – report of over 900 stage pT1b1- to pT2b-tumors JF - Pathology - Research and Practice KW - Gebärmutterhalskrebs KW - Chirurgie KW - Gewebe KW - Gebärmutterentfernung Y1 - 2000 VL - 196 SP - 450 ER - TY - JOUR A1 - Kopper, Andreas A1 - Klotz, Stefan A1 - Westner, Markus A1 - Strahringer, Susanne T1 - Shadow IT and Business-managed IT BT - Practitioner Perceptions and Their Comparison to Literature JF - Journal of Information Technology Management (JITM) N2 - Two concepts describe the autonomous deployment of IT by business entities: Shadow IT and Business-managed IT. Shadow IT is deployed covertly, that is, software, hardware, or IT services created/procured or managed by business entities without alignment with the IT organization. In contrast, Business-managed IT describes the overt deployment of IT, that is, in alignment with the IT organization or in a split responsibility model. The purpose of this paper is to extend the conceptual understanding of Shadow IT and Business-managed IT, comparing the perceptions of 29 CIOs and senior IT managers with the results of a systematic literature review. By doing so, this paper presents a structured and comprehensive view of causing factors, outcomes, and governance of Shadow IT and Business-managed IT in practice. A comparison of academic literature and practitioner perceptions reveals the limitations and gaps of the current research and highlights avenues for future research. The authors find three category-spanning themes occurring as causing factors, outcomes, and—as part of governance measures—factors to improve the IT organization: (1) (Poor) business-IT alignment (2) (lack of) agility, and (3) (lack of) policies. This study is innovative with its comprehensive qualitative interview data that the authors compare to the existing literature. Therefore, the paper brings together theoretical and practical insights into Shadow IT and Businessmanaged IT, which should aid practitioners and scholars in decision making and future research. KW - Corporate Governance KW - Strategisches Management KW - Shadow IT KW - Business-managed IT KW - IT governance KW - Agility KW - Business-IT alignment KW - Informationsmanagement Y1 - 2019 UR - http://home.thejitm.org/XXX-4/contents.html SN - 1042-1319 VL - 30 IS - 4 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta T1 - Familial cancer history in patients with carcinoma of the cervix uteri JF - European Journal of Obstetrics & Gynecology and Reproductive Biology KW - Gebärmutterhalskrebs KW - Familienanamnese Y1 - 2002 U6 - https://doi.org/10.1016/s0301-2115(01)00520-6 VL - 101 IS - 1 SP - 54 EP - 57 ER - TY - JOUR A1 - Horn, Lars-Christian A1 - Fischer, Uta A1 - Tannapfel, A. A1 - Kuhn, H. A1 - Hänel, C. A1 - Raptis, Georgios T1 - The role of p53 tumorsuppressorgene in tumor progression in cervical cancer JF - Pathology - Research and Practice KW - Tumorsuppressor-Gen KW - Tumorwachstum KW - Gebärmutterhalskrebs Y1 - 1999 VL - 195 SP - 328 ER - TY - CHAP A1 - Raptis, Georgios T1 - Die Konzepte und Mechanismen der elektronischen Gesundheitskarte und des Heilberufsausweises aus der Sicht der Datensicherheit / des Datenschutzes BT - Vortrag T2 - Forschungsseminar med. Informatik an der Universität Heidelberg, 22.06.2006 KW - Elektronische Gesundheitskarte KW - Heilberuf KW - Ausweis KW - Datenschutz KW - Datensicherheit Y1 - 2005 ER - TY - CHAP A1 - Raptis, Georgios T1 - Empfehlungen der BÄK zum Datenschutz im Praxisalltag, Darstellung unter technischen Aspekten BT - Vortrag im Rahmen der conhIT 2009, Berlin, 22.04.2009, zertifiziert von der Ärztekammer Berlin T2 - conhIT 2009, Berlin, 22.04.2009 KW - Arztpraxis KW - Datenschutz Y1 - 2009 ER - TY - CHAP A1 - Raptis, Georgios T1 - Health Professional eIDs vis-á-vis a Single Market Perspective BT - Vortrag T2 - European Health Telematics Association, Berlin, 25.10.2011 KW - eArztausweis KW - Elektronischer Arztausweis Y1 - 2011 ER - TY - JOUR A1 - De Pieri, Enrico A1 - Atzori, Federica A1 - Ferguson, Stephen J. A1 - Dendorfer, Sebastian A1 - Leunig, Michael A1 - Aepli, Martin T1 - Contact force path in total hip arthroplasty: effect of cup medialisation in a whole-body simulation JF - HIP International N2 - Background: Cup medialisation down to the true acetabular floor in total hip arthroplasty with a compensatory femoral offset increase seems to be mechanically advantageous for the abductor muscles due to the relocation of the lever arms (body weight lever arm decreased, abductor lever arm increased). However, limited information is currently available about the effects of this reconstruction type at the head cup interface, compared to an anatomical reconstruction that maintains the natural lever arms. Through a whole-body simulation analysis, we compared medialised versus anatomical reconstruction in THA to analyse the effects on: (1) contact force magnitude at the head cup interface; (2) contact force path in the cup; and (3) abductor activity. Methods: Musculoskeletal simulations were performed to calculate the above-mentioned parameters using inverse dynamics analysis. The differences between the virtually implanted THAs were calculated to compare the medialised versus anatomical reconstruction. Results: Cup medialisation with compensatory femoral offset increase led to: (1) a reduction in contact force magnitude at the head cup interface up to 6.6%; (2) a similar contact force path in the cup in terms of sliding distance and aspect ratio; and (3) a reduction in abductor activity up to 17.2% (gluteus medius). Conclusions: In our opinion, these potential biomechanical gains do not generally justify a fully medialised reconstruction, especially in younger patients that are more likely to undergo revision surgery in their lifetime. Cup medialisation should be performed until sufficient press fit and bony coverage of a properly sized and oriented cup can be achieved. KW - Cup medialisation KW - femoral offset KW - hip contact force KW - total hip anthroplasty KW - total hip replacement KW - Hüftgelenkprothese KW - Kontaktkraft KW - Biomechanische Analyse KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1177/1120700020917321 VL - 31 IS - 5 SP - 624 EP - 631 PB - Sage ER - TY - INPR A1 - Bock, Sebastian A1 - Weiß, Martin Georg T1 - Rotation Detection of Components with Convolutional Neural Networks N2 - The main issues in many image processing applications are object recognition and detection of objects, which answers the questions whether an object is present and if it is present, where it is located. Popular object detection algorithms like YOLO use a regression formulation for the whole problem, especially for the bounding box parameters. In production industry the setting usually is different: One usually knows the object type and rather wants to know with high precision where the object is. We study a prototype application in this area where we identify the rotation of an object in a plane. To solve this problem use a regression approach with a CNN architecture as a function approximator. We compare our results to standard image processing algorithms, which do not use neural networks, and present quantitative results on the accuracy. CNNs seem at least competitive to classical image processing. KW - Neural networks KW - Network Architecture KW - CNN KW - Functionapproximation KW - Image orientation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-4120 ER - TY - JOUR A1 - Höh, H. A1 - Gamael, A. A1 - Raptis, Georgios T1 - Energie und Phakozeit bei Ultraschall und Laserphakoemulsifikation JF - Klinische Monatsblätter für Augenheilkunde KW - Phakoemulsifikation KW - Ultraschall Y1 - 2000 VL - 217 IS - Suppl. 8 SP - 5 ER - TY - JOUR A1 - Lekakis, J. A1 - Nanas, J. A1 - Prassopoulos, V. A1 - Raptis, Georgios T1 - Cardiac I-123 metaiodobenzylguanidine uptake in predicting early and late mortality in patients with congestive heart failure JF - Circulation (Suppl.) KW - Stauungssuffizienz KW - Radiologische Diagnostik KW - Prognose Y1 - 1997 VL - 96 IS - 8 SP - 2104 ER - TY - GEN A1 - Raptis, Georgios T1 - Biometrie - Anwendungen und Datenschutz. Welche Zusatzinformationen liefert der IRIS-Pförtner? Nebennutzen in einem biometrischen Zugangskontrollsystem. Medizinische Hintergründe. Symposium des Bundesamtes für Sicherheit in der Informationstechnik, Vortrag, Darmstadt 23. Mai 2002 BT - Vortrag, Darmstadt 23. Mai 2002 T2 - Symposium des Bundesamtes für Sicherheit in der Informationstechnik Y1 - 2002 ER - TY - CHAP A1 - Wiesmaier, Alexander A1 - Lippert, Markus A1 - Karatsiolis, Vangelis A1 - Raptis, Georgios A1 - Buchmann, Johannes T1 - An Evaluated Certification Services System for the German National Root CA - Legally Binding and Trustworthy Transactions in E-Business and E-Government T2 - Proceedings of The 2005 International Conference on E-Business, Enterprise Information Systems, E-Government, and Outsourcing, EEE 2005, Las Vegas, Nevada, USA, June 20-23, 2005 Y1 - 2005 SN - 1-932415-76-9 SP - 103 EP - 108 PB - CSREA Press ER - TY - GEN A1 - Raptis, Georgios T1 - Übersicht über die neuen Technischen Richtlinien des BSI zum ersetzenden Scannen und zur Langzeitarchivierung BT - Vortrag T2 - Telemed 2014, Berlin, 14.10.2014 Y1 - 2014 ER - TY - GEN A1 - Raptis, Georgios T1 - Mögliche Auswirkungen der eIDAS-Verordnung auf die Telematikinfrastruktur und die eArztausweise BT - Vortrag T2 - CAST-Workshop PKI, Darmstadt, 29.01.2015 KW - Europäische Union KW - Telemedizin KW - eArztausweis KW - Elektronischer Arztausweis Y1 - 2015 ER - TY - GEN A1 - Raptis, Georgios T1 - HPCs als Basis für den elektronischen Arztausweis BT - Vortrag T2 - Smartcard-Workshops, Fraunhofer SIT, 07.02.2006 KW - Arzt KW - Ausweis KW - Hochleistungsrechnen Y1 - 2006 ER - TY - GEN A1 - Raptis, Georgios T1 - Ist die Sicherheit der medizinischen Daten in der Telematik-Infrastruktur zu gewährleisten? BT - Vortrag an der Universität Heidelberg, Kolloquium Wissenschaftlichkeit in der Medizin, 10.05.2007 T2 - Kolloquium Wissenschaftlichkeit in der Medizin, Universität Heidelberg, 10.05.2007 KW - Telemedizin KW - Datensicherheit Y1 - 2007 ER - TY - GEN A1 - Raptis, Georgios T1 - Datenschutz und IT-Sicherheit: Empfehlungen von BÄK und KBV für Ärzte BT - Vortrag T2 - AK-Sicherheit des eco-Verband der deutschen Internetwirtschaft e.V., Köln, 06.05.2009 KW - Arztpraxis KW - Datenschutz KW - Datensicherheit Y1 - 2009 ER - TY - THES A1 - Raptis, Georgios T1 - Klassifikation, Anwendungen und Sicherheitskonzept von Trustcentern KW - Trust Center Y1 - 2004 ER - TY - GEN A1 - Raptis, Georgios T1 - Mechanismen und Einsatzkonzepte von Heilberufsausweis und elektronischer Gesundheitskarte BT - Vortrag T2 - Oberseminar im Fachbereich Informatik, Kryptographie und Computeralgebra der TU-Darmstadt, 28.11.2006 KW - Elektronische Gesundheitskarte KW - Heilberuf KW - Ausweis Y1 - 2006 ER - TY - JOUR A1 - Schenkel, Johannes A1 - Albert, Jürgen A1 - Raptis, Georgios A1 - Butz, Norbert ED - Duesberg, Felix T1 - Notfalldatenmanagement auf der elektronischen Gesundheitskarte JF - e-Health KW - Elektronische Gesundheitskarte KW - Notfallmedizin Y1 - 2012 SP - 64 EP - 67 PB - medical future verlag CY - Solingen ER - TY - JOUR A1 - Aurbach, Maximilian A1 - Spicka, Jan A1 - Süß, Franz A1 - Dendorfer, Sebastian T1 - Evaluation of musculoskeletal modelling parameters of the shoulder complex during humeral abduction above 90° JF - Journal of Biomechanics N2 - Based on electromyographic data and force measurements within the shoulder joint, there is an indication that muscle and resulting joint reaction forces keep increasing over an abduction angle of 90°. In inverse dynamics models, no single parameter could be attributed to simulate this force behaviour accordingly. The aim of this work is to implement kinematic, kinetic and muscle model modifications to an existing model of the shoulder (AnyBody™) and assess their single and combined effects during abduction up to 140° humeral elevation. The kinematics and the EMG activity of 10 test subjects were measured during humeral abduction. Six modifications were implemented in the model: alternative wrapping of the virtual deltoid muscle elements, utilization of a three element Hill model, strength scaling, motion capture driven clavicle elevation/protraction, translation of the GH joint in dependency of the acting forces and an alteration of the scapula/clavicle rhythm. From the six modifications, 16 different combinations were considered. Parameter combinations with the Hill model changed the resultant GH joint reaction force and led to an increase in force during abduction of the humerus above 90°. Under the premise of muscle activities and forces within the GH joint rising after 90° of humeral abduction, we propose that the Hill type muscle model is a crucial parameter for accurately modelling the shoulder. Furthermore, the outcome of this study indicates that the Hill model induces the co-contraction of the muscles of the shoulder without the need of an additional stability criterion for an inverse dynamics approach. KW - Shoulder joint KW - Musculoskeletal modelling KW - EMG KW - Glenohumeral joint reaction force KW - Muscle model KW - Schultergelenk KW - Bewegungsapparat KW - Biomechanik KW - Simulation Y1 - 2020 U6 - https://doi.org/10.1016/j.jbiomech.2020.109817 VL - 106 IS - June PB - Elsevier ER - TY - GEN A1 - Raptis, Georgios T1 - Einsatzmöglichkeiten des elektronischen Heilberufsausweises BT - Vortrag im Rahmen des CAST-Forums, Fraunhofer IGD, 14.09.2006 T2 - CAST-Forums, Fraunhofer IGD, 14.09.2006 KW - Heilberuf KW - Ausweis Y1 - 2006 ER - TY - JOUR A1 - Raptis, Georgios T1 - App statt Arzt ist kein gutes Motto BT - Interview JF - medizin & technik Y1 - 2013 UR - https://medizin-und-technik.industrie.de/medizin/mediziner-ueber-technik/app-statt-arzt-ist-kein-gutes-motto/ IS - 2 ER - TY - CHAP A1 - Raptis, Georgios T1 - Notfalldaten und Datenerhalt mit der elektronischen Gesundheitskarte. T2 - Tagungsband 22. Smartcard-Workshop 2012 KW - Elektronische Gesundheitskarte KW - Notfallmedizin KW - Datensicherung Y1 - 2012 SP - 166 PB - Fraunhofer-Verlag ER - TY - JOUR A1 - Fischer, Uta A1 - Raptis, Georgios A1 - Horn, Lars-Christian T1 - Bedeutung der Familienanamnese bei Zervixkarzinom JF - Zentralblatt für Gynäkologie N2 - Fragestellung: Molekulare Analysen haben deutlich gemacht, dass maligne Tumoren durch Veränderungen des Genoms hervorgerufen werden. Im Gegensatz zu den erblich bedingten Tumorerkrankungen sind die Kenntnisse zur Bedeutung familiärer Faktoren bei den sog. sporadischen Tumoren, insbesondere beim Zervixkarzinom (CX) begrenzt. Material und Methode: Patientinnen des CX-Registers der Universitäts-Frauenklinik wurden retrospektiv bezüglich der Familienanamnese (FA) analysiert. Als positive FA wurde eine maligne Tumorerkrankung bei einem oder mehreren Verwandten ersten Grades definiert. Es wurde unterschieden, ob es sich um Zervixkarzinome, andere gynäkologische Malignome (außer Mammakarzinom) oder eine extragenitale Lokalisation handelte. Diese Daten wurden zum Erkrankungsalter und zum Nachweis pelviner Lymphknotenmetastasen in Beziehung gesetzt. Ergebnisse: 159/737 Frauen (21,6 %) wiesen eine positive FA auf. In 10,7 % der Fälle war mehr als ein Verwandter ersten Grades erkrankt; bei 6,9 % Angehörige ersten und zweiten Grades. Weibliche Verwandte ersten Grades von 42 Frauen wiesen Malignome des weiblichen Genitaltraktes (außer CX) auf. In 6,9 % waren die Mutter und/oder die Schwester an einem Zervixkarzinom erkrankt. Das Durchschnittsalter der Patientinnen mit positiver Familienanamnese (FA) unterschied sich nicht von dem derjenigen mit leerer FA, wohl aber bei getrennter Betrachtung nach der Tumorlokalisation. Bezüglich des Tumorstadiums (pTNM) und der Zahl der Patientinnen mit histologisch nachgewiesenen pelvinen Lymphknotenmetastasen bestand kein Unterschied. Schlussfolgerungen: Die bisherigen Ergebnisse deuten auch beim Zervixkarzinom auf eine familiäre Belastung hin. Dabei existieren offenbar Familien, in denen mit HPV-assoziierte Präkanzerosen bzw. Tumoren vermehrt auftreten. Besonders gefährdet sind Patientinnen, deren weibliche Anverwandte ersten Grades bereits an einer zervikalen Präkanzerose (besonders CIN III) oder einem invasiven CX erkrankt sind. Diese Frauen sollten einem engmaschigen Screening unterzogen werden. T2 - Impact of familiar history in cervical cancer patients KW - Gebärmutterhalskrebs KW - Familienanamnese KW - Zervixkarzinom KW - hereditär KW - familiär KW - Anamnese KW - Karzinom KW - Prognose Y1 - 2001 U6 - https://doi.org/10.1055/s-2001-14791 VL - 123 SP - 302 EP - 307 ER - TY - GEN A1 - Horn, Lars-Christian A1 - Raptis, Georgios A1 - Fischer, Uta T1 - Familiäres Zervixkarzinom – Erste Ergebnisse BT - Poster T2 - 54. Kongress der Deutschen Gesellschaft für Gynäkologie und Geburtshilfe KW - Gebärmutterhalskrebs KW - Familienanamnese Y1 - 2002 ER - TY - CHAP A1 - Raptis, Georgios T1 - Ein Verfahren zur Lösung des Problems der kryptographischen Langzeitsicherheit medizinischer Daten, die in einer Infrastruktur gespeichert werden T2 - BIOSIG-Konferenz 2007, Darmstadt N2 - Medizinische Daten, die - wie derzeit für die Telematik-Infrastruktur nach §291a SGB V spe-zifiziert - auch außerhalb der physischen Kontrolle der Eigentümer oder Ersteller (also z.B. außerhalb von Arztpraxen oder Klinken) auf Servern kryptographisch verschlüsselt gespeichert werden, müssen sehr lange vertraulich bleiben. Insbesondere darf der technische Betreiber des Servers, der die Daten speichert, keinen Zugriff erlangen. Es kann jedoch keine verlässliche Aussage dahingehend getroffen werden, ob die heute eingesetzten kryp-tographischen Algorithmen in 30 oder 40 Jahren die Vertraulichkeit der medizinischen Daten weiterhin gewährleisten. Es wird ein Verfahren vorgestellt, welches das Problem der langfristigen Sicherheit von verschlüsselt gespeicherten medizinischen Daten aus kryptographischer Sicht löst. Die Anwendung des Verfahrens wird am Beispiel einer nach den derzeit bekannten gematik-Spezifikationen definierten Infrastruktur veranschaulicht. Es wird von einer getrennten Speicherung von verschlüsselten medizinischen Daten und Schlüsselmaterial ausgegangen. Die Daten werden an der Datenquelle (Konnektor, z.B. eines Arztes) mit einem Einmalblock (One Time Pad, OTP) verschlüsselt. Sie sind damit beweisbar sicher verschlüsselt, weil das One-Time-Pad-Verschlüsselungsverfahren beweisbar „perfekt geheim“ ist. Der OTP-Schlüssel wird mit einem symmetrischen Schlüssel verschlüsselt, der wiederum mit den asymmetrischen Schlüsseln aller Zugriffsberechtigten verschlüsselt wird. Die kryptographische, technische und organisatorische Sicherheit des Verfahrens sowie seine Voraussetzungen und Kosten werden analysiert. KW - Gesundheitsinformationssystem KW - Datensicherhung KW - Kryptologie Y1 - 2007 UR - http://www.baek.de/downloads/Raptis_Verfahren-2.pdf ER - TY - GEN A1 - Raptis, Georgios T1 - Papierlose Praxis & Digitalisierung BT - Vortrag T2 - 6. BMVZ-Praktikerkongress des Bundesverbands Medizinische Versorgungszentren - Gesundheitszentren - Integrierte Versorgung e.V, 12.09.2012 Berlin, zertifiziert von der Ärztekammer Berlin KW - Arztpraxis KW - Digitalisierung Y1 - 2012 ER - TY - GEN A1 - Raptis, Georgios T1 - Sichere Gesundheitsdaten in der Cloud? Technische Voraussetzungen und Regelungen BT - Vortrag T2 - 8. Rhein-Main Zukunftskongress Krankenhaus & Partner 2014, Offenbach, 21.2.2014 KW - Cloud Computing KW - Gesundheitsinformationssystem KW - Datenschutz Y1 - 2014 ER - TY - GEN A1 - Raptis, Georgios T1 - Vernetzung und ubiquitäre Informationsverarbeitung – technisch-organisatorischer Datenschutz in der Arztpraxis BT - Vortrag in der 2. Fachtagung der Gesellschaft für Datenschutz und Datensicherheit e.V. (GDD), Berlin, 13.05.2014, zertifiziert von der Ärztekammer Berlin T2 - 2. Fachtagung der Gesellschaft für Datenschutz und Datensicherheit e.V. (GDD), Berlin, 13.05.2014, zertifiziert von der Ärztekammer Berlin KW - Arztpraxis KW - Datenschutz Y1 - 2014 ER - TY - GEN A1 - Raptis, Georgios T1 - Mobile Szenarien für Anwendungen der eGK BT - Vortrag T2 - CAST-Workshop Smartcards, Darmstadt, 25.09.2014 KW - Elektronische Gesundheitskarte Y1 - 2014 ER - TY - GEN A1 - Raptis, Georgios T1 - Die elektronische Gesundheitskarte BT - Vortrag T2 - 7. Kommunikationsforum "Industry meets Medicine", Olpe, 5.11.2014 KW - Elektronische Gesundheitskarte Y1 - 2014 ER - TY - JOUR A1 - Raptis, Georgios T1 - Computer können Ärzte nicht ersetzen BT - Interview JF - Technology Review Y1 - 2014 VL - 11 SP - 82 ER - TY - GEN A1 - Raptis, Georgios T1 - Datenschutzfragen zur Telemedizin BT - Vortrag T2 - Fachtagung Datenschutz in der Medizin - Update 2015 I, Hamburg 03.02.2015 KW - Telemedizin KW - Datenschutz Y1 - 2015 ER - TY - BOOK A1 - Sauer, S. A1 - Wolf, Th. A1 - Buch, M. A1 - Raptis, Georgios T1 - Sichere Client-Server-Architekturen für E-Government BT - E-Government-Handbuch KW - Client-Server-Konzept KW - Datensicherheit KW - E-Government Y1 - 2004 ER - TY - JOUR A1 - Raptis, Georgios T1 - Kryptographischer Langzeitschutz JF - KES - The Information Security Journal KW - Kryptologie KW - Datensicherung Y1 - 2008 VL - 1 SP - 55 EP - 62 ER - TY - JOUR A1 - Busch, Ch. A1 - Daum, H. A1 - Raptis, Georgios T1 - Merkmal Iris. Können diese Augen lügen? JF - Spektrum der Wissenschaft KW - Biometrie KW - Mustererkennung KW - Iris KW - Regenbogenhaut Y1 - 2003 UR - https://www.spektrum.de/magazin/koennen-diese-augen-luegen/829906 IS - 7 SP - 81 EP - 82 ER - TY - THES A1 - Raptis, Georgios T1 - Vertraulichkeit von medizinischen Daten in der Telematik-Infrastruktur - Sicherheitsanalyse unter Berücksichtigung von Aspekten der langfristigen Sicherheit KW - Medizinische Dokumentation KW - Telekommunikation KW - Datensicherheit Y1 - 2008 CY - Heidelberg ER - TY - RPRT A1 - Schenkel, Johannes A1 - Albert, Jürgen A1 - Raptis, Georgios T1 - Arbeitskonzept Notfalldatenmanagement KW - Elektronische Gesundheitskarte KW - Notfallmedizin Y1 - 2011 UR - www.bundesaerztekammer.de/downloads/Arbeitskonzept_NFDM_1.051.pdf ER - TY - JOUR A1 - Schenkel, Johannes A1 - Albert, Jürgen A1 - Raptis, Georgios A1 - Butz, Norbert T1 - Notfalldatensatz: Bessere Unterstützung für den Arzt JF - Deutsches Ärzteblatt KW - Elektronische Gesundheitskarte KW - Notfallmedizin Y1 - 2011 UR - https://www.aerzteblatt.de/pdf.asp?id=89546 VL - 108 IS - 19 SP - A-1046, B-864, C-864 ER - TY - CHAP A1 - Metzler, V. A1 - Aach, T. A1 - Palm, Christoph A1 - Lehmann, Thomas M. T1 - Texture Classification of Graylevel Images by Multiscale Cross-Co-Occurrence Matrices T2 - Proceedings 15th International Conference on Pattern Recognition (ICPR-2000) N2 - Local gray level dependencies of natural images can be modelled by means of co-occurrence matrices containing joint probabilities of gray-level pairs. Texture, however, is a resolution-dependent phenomenon and hence, classification depends on the chosen scale. Since there is no optimal scale for all textures we employ a multiscale approach that acquires textural features at several scales. Thus linear and nonlinear scale-spaces are analyzed by multiscale co-occurrence matrices that describe the statistical behavior of a texture in scale-space. Classification is then performed on the basis of texture features taken from the individual scale with the highest discriminatory power. By considering cross-scale occurrences of gray level pairs, the impact of filters on the feature is described and used for classification of natural textures. This novel method was found to improve classification rates of the common co-occurrence matrix approach on standard textures significantly. Y1 - 2000 U6 - https://doi.org/10.1109/ICPR.2000.906133 SP - 549 EP - 552 ER - TY - CHAP A1 - Palm, Christoph A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus T1 - Color Texture Analysis of Moving Vocal Cords Using Approaches from Statistics and Signal Theory T2 - Advances in Quantitative Laryngoscopy, Voice and Speech Research, Procs. 4th International Workshop, Friedrich Schiller University, Jena N2 - Textural features are applied for detection of morphological pathologies of vocal cords. Cooccurrence matrices as statistical features are presented as well as filter bank analysis by Gabor filters. Both methods are extended to handle color images. Their robustness against camera movement and vibration of vocal cords is evaluated. Classification results due to three in vivo sequences are in between 94.4 % and 98.9%. The classification errors decrease if color features are used instead of grayscale features for both statistical and Fourier features KW - Color Texture KW - Gabor Filter KW - Cooccurrence Matrix KW - Image Processing Y1 - 2000 SP - 49 EP - 56 ER - TY - CHAP A1 - Palm, Christoph A1 - Fischer, B. A1 - Lehmann, Thomas M. A1 - Spitzer, Klaus T1 - Hierarchische Wasserscheiden-Transformation zur Lippensegmentierung in Farbbildern T2 - Bildverarbeitung für die Medizin 2000 N2 - Zur Lösung komplexer Segmentierungsprobleme wird eine hierarchische und farbbasierte Wasserscheidentransformation vorgestellt. Geringe Modifikationen bezüglich Startpunktwahl und Flutungsprozess resultieren in signifikanten Verbesserungen der Segmentierung. Das Verfahren wurde zur Lippendetektion in Farbbildsequenzen eingesetzt, die zur quantitativen Beschreibung von Sprechbewegungsabläufen automatisch ausgewertet werden. Die Experimente mit 245 Bildern aus 6 Sequenzen zeigten eine Fehlerrate von 13%. KW - Hierarchische Wasserscheiden-Transformation KW - Segmentierung der Lippen KW - Bewegungsanalyse KW - Farbbildverarbeitung Y1 - 2000 U6 - https://doi.org/10.1007/978-3-642-59757-2_20 SP - 106 EP - 110 PB - Springer CY - Berlin ER - TY - CHAP A1 - Aurbach, Maximilian A1 - Wagner, Kilian A1 - Süß, Franz A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - Implementation and Validation of Human Kinematics Measured Using IMUs for Musculoskeletal Simulations by the Evaluation of Joint Reaction Forces T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017, Sarajevo, Bosnia and Herzegovina N2 - The gold standard for the analysis of human kinematics and kinetics is a camera-based motion capture system in combination with force measurement platforms. Alternatively, inertial measurement units can be utilized to obtain human kinematics, while ground reaction forces are computed from full body dynamics. This setup represents a system independent from the spatial confinement of a gait laboratory. The aim of this study is the comparison of the two methods by the investigation of lower limb kinematics and the resulting joint reaction forces within the ankle-, knee- and hip joints. For this purpose, human motion during gait was captured simultaneously by both measurement techniques. 13 trials from 8 different test subjects were evaluated in total. IMU data was processed with a quaternion based Kalman Filter. The data sets were implemented into a musculoskeletal simulation program in order to drive a virtual human body model. Each sensor was aligned to the gravitational and magnetic field vectors of the earth. The angles of flexions, extensions and rotations were analyzed to determine kinematic differences. Joint reaction forces defined kinetic dissimilarities. The overall kinematic differences of both models yielded root mean square errors of 7.62°, 6.02°, 4.95°, 2.79°, 2.38° and 3.56° for ankle flexion, subtalar eversion, knee flexion, hip external rotation, hip abduction and hip flexion, respectively. The proximo-distal differences in force peaks between the models yielded overall for the ankle, 57.33 %Bodyweight(BW) ± 46.86 %BW (16.66 %(Maximum peak to peak) ± 13.62 %) for the knee 37.09 %BW ± 29.33 %BW (17.65 % ± 15.44 %) and 32.03 %BW ± 24.33 %BW (15.6 % ± 12.54 %) for the hip. The overall outcome of this work investigated an approach independent of the common setup of the gait laboratory, thus enabling a cheaper and more flexible technology as an alternative. However, kinematic and thus kinetic differences remain rather large. Future work aims to improve the contact criterion for the calculation of the ground reaction forces and the implementation of a full-body calibration algorithm for the IMU system in order to counteract magnetic field disturbances. KW - Inertial Measurement Units KW - Multibody Simulation KW - Musculoskeletal Simulation KW - AnyBody KW - Motion Capture KW - Bewegungsapparat KW - Biomechanik KW - Motion Capturing KW - Mehrkörpersimulation KW - Ground Reaction Force Prediction KW - Gait KW - IMU KW - Joint Reaction Forces Y1 - 2017 U6 - https://doi.org/10.1007/978-981-10-4166-2_31 VL - Vol. 62 SP - 205 EP - 211 PB - Springer CY - Singapore ER - TY - CHAP A1 - Jungtäubl, Dominik A1 - Schmitz, Paul A1 - Gross, Simon A1 - Dendorfer, Sebastian ED - Badnjevic, Almir T1 - FEA of the transiliacal internal fixator as an osteosynthesis of pelvic ring fractures T2 - CMBEBIH 2017, Proceedings of the International Conference on Medical and Biological Engineering 2017 N2 - Common Schanz screw systems can be used to stabilize pelvic ring fractures. In order to accommodate for different patient’s requirements, implants can be placed in cranio-caudal direction into the os ilium (T1), or into the supraacetabular bone canal, and thus, in dorso-ventral direction (T2). Whereas both techniques are currently used, no data of the biomechanical behavior is available up to this date. The aim of this study is to analyze, whether T2 shows biomechanical advantages with respect to tissue and implant stresses due to the enlarged bone-implant interface. Forces acting on the pelvis were analyzed using motion capture data of a gait cycle obtained by the utilization of a musculoskeletal simulation program. A three dimensional finite element (FE) model of the pelvis with grayscale-based material properties was generated. The muscle and joint reaction forces at toe-off were applied to the FE model and instable pelvis fractures were implemented. The osteosynthesis systems were positioned within the model in order to enable the comparison between the two different surgical techniques. Stresses and displacements were analyzed for bone tissue, fracture zone and implant. T2 lead to approx. 30% larger displacements in the fracture zone. Von-Mises stresses were larger for T2 in the implant (80 MPa vs. 227 MPa), whereas T1 leads to larger stresses in the bone tissue (200 MPa vs. 140 MPa). Both implantation techniques showed a good biomechanical behavior. Differences could be found with respect to tissue strains and deformations in the fracture zone. If bone quality or fracture healing are of concern, T2 or T1 should be used, respectively. However, both techniques seem to be applicable for cases with no special requirements. Further analyses aim to investigate the behavior under cyclic loading. KW - Finite element analysis KW - Musculoskeletal simulation KW - Internal fixator KW - Pelvic ring fracture KW - Beckenbruch KW - Operationstechnik KW - Finite-Elemente-Methode KW - Biomechanik KW - Simulation Y1 - 2017 SN - 978-981-10-4165-5 U6 - https://doi.org/10.1007/978-981-10-4166-2_32 SP - 212 EP - 217 PB - Springer CY - Singapore ER - TY - JOUR A1 - Ignasiak, Dominika A1 - Dendorfer, Sebastian A1 - Ferguson, Stephen J. T1 - Thoracolumbar spine model with articulated ribcage for the prediction of dynamic spinal loading JF - Journal of Biomechanics N2 - Musculoskeletal modeling offers an invaluable insight into the spine biomechanics. A better understanding of thoracic spine kinetics is essential for understanding disease processes and developing new prevention and treatment methods. Current models of the thoracic region are not designed for segmental load estimation, or do not include the complex construct of the ribcage, despite its potentially important role in load transmission. In this paper, we describe a numerical musculoskeletal model of the thoracolumbar spine with articulated ribcage, modeled as a system of individual vertebral segments, elastic elements and thoracic muscles, based on a previously established lumbar spine model and data from the literature. The inverse dynamics simulations of the model allow the prediction of spinal loading as well as costal joints kinetics and kinematics. The intradiscal pressure predicted by the model correlated well (R2=0.89) with reported intradiscal pressure measurements, providing a first validation of the model. The inclusion of the ribcage did not affect segmental force predictions when the thoracic spine did not perform motion. During thoracic motion tasks, the ribcage had an important influence on the predicted compressive forces and muscle activation patterns. The compressive forces were reduced by up to 32%, or distributed more evenly between thoracic vertebrae, when compared to the predictions of the model without ribcage, for mild thoracic flexion and hyperextension tasks, respectively. The presented musculoskeletal model provides a tool for investigating thoracic spine loading and load sharing between vertebral column and ribcage during dynamic activities. Further validation for specific applications is still necessary. KW - Inverse dynamics KW - Musculoskeletal model KW - Thoracolumbar spine KW - Brustwirbelsäule KW - Brustkorb KW - Biomechanik KW - Mechanische Belastung KW - Prognose Y1 - 2016 U6 - https://doi.org/10.1016/j.jbiomech.2015.10.010 VL - vol. 49 IS - 6 SP - 959 EP - 966 PB - Elsevier Science ER - TY - JOUR A1 - Lazarev, Igor A. A1 - Ryabokon, P.V. A1 - Haller, M. A1 - Dendorfer, Sebastian T1 - Effect of the fractured calcaneus's peripheral fragment displacement on the triceps surae function JF - ЖУРНАЛ «ТРАВМА» Ukrainian Trauma Journal Y1 - 2015 VL - 2, TOM 16 ER - TY - JOUR A1 - Weber, Tim A. A1 - Dendorfer, Sebastian A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias ED - Takagi, Michiaki T1 - Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions? JF - BioMed Research International N2 - We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of “femur first/combined anteversion,” which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient’s gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome. KW - Hüftgelenkprothese KW - Operationstechnik KW - Computerunterstütztes Verfahren KW - Bewegungsapparat KW - Mechanische Belastung Y1 - 2015 U6 - https://doi.org/10.1155/2015/625317 VL - 2015 SP - ID 625317 ER - TY - JOUR A1 - Weber, Markus A1 - Weber, Tim A. A1 - Woerner, Michael A1 - Craiovan, Benjamin A1 - Worlicek, Michael A1 - Winkler, Sebastian A1 - Grifka, Joachim A1 - Renkawitz, Tobias T1 - The impact of standard combined anteversion definitions on gait and clinical outcome within one year after total hip arthroplasty JF - International Orthopaedics N2 - Different target areas within the concept of combined cup and stem anteversion have been published for total hip arthroplasty (THA). We asked whether component positioning according to eight standard combined anteversion rules is associated with (1) more physiological gait patterns, (2) higher improvement of gait variables and (3) better clinical outcome after THA.In a prospective clinical study, 60 patients received cementless THA through an anterolateral MIS approach in a lateral decubitus position. Six weeks postoperatively, implant position was analysed using 3D-CT by an independent external institute. Preoperatively, six and 12 months postoperatively range of motion, normalized walking speed and hip flexion symmetry index were measured using 3D motion-capture gait analysis. Patient-related outcome measures (HHS, HOOS, EQ-5D) were obtained by an observer blinded to 3D-CT results. Eight combined anteversion definitions and Lewinnek's "safe zone" were evaluated regarding their impact on gait patterns and clinical outcome.Combined cup and stem anteversion according to standard combined anteversion definitions as well as cup placement within Lewinnek's "safe zone" did not influence range of motion, normalized walking speed and/or hip flexion symmetry index six and 12 months after THA. Similarly, increase of gait parameters within the first year after THA was comparable between all eight combined anteversion rules. Clinical outcome measures like HHS, HOOS and EQ-5D did not show any benefit for either of the combined anteversion definitions.Standard combined cup and stem anteversion rules do not improve postoperative outcome as measured by gait analysis and clinical scores within one year after THA. KW - Total hip athroplasty KW - Combined anteversion KW - Outcome KW - Gait analysis KW - Hüftgelenkprothese KW - Bewegungsanalyse KW - Gehen KW - Funktionelle Anatomie Y1 - 2015 U6 - https://doi.org/10.1007/s00264-015-2777-8 VL - 39 IS - 12 SP - 2323 EP - 2333 ER - TY - JOUR A1 - Weber, Tim A1 - Al-Munajjed, Amir Andreas A1 - Verkerke, Gijsbertus Jacob A1 - Dendorfer, Sebastian A1 - Renkawitz, Tobias T1 - Influence of minimally invasive total hip replacement on hip reaction forces and their orientations JF - Journal of Orthopaedic Research N2 - Minimally invasive surgery (MIS) is becoming increasingly popular. Supporters claim that the main advantages of MIS total hip replacement (THR) are less pain and a faster rehabilitation and recovery. Critics claim that safety and efficacy of MIS are yet to be determined. We focused on a biomechanical comparison between surgical standard and MIS approaches for THR during the early recovery of patients. A validated, parameterized musculoskeletal model was set to perform a squat of a 50th percentile healthy European male. A bilateral motion was chosen to investigate effects on the contralateral side. Surgical approaches were simulated by excluding the incised muscles from the computations. Resulting hip reaction forces and their symmetry and orientation were analyzed. MIS THR seemed less influential on the symmetry index of hip reaction forces between the operated and nonoperated leg when compared to the standard lateral approach. Hip reaction forces at peak loads of the standard transgluteal approach were 24% higher on the contralateral side when compared to MIS approaches. Our results suggest that MIS THR contributes to a greater symmetry of hip reaction forces in absolute value as well as force-orientation following THR. KW - THA KW - THR KW - Biomechanics KW - Conventional surgery KW - Early recovery KW - Hüftgelenkprothese KW - Minimal-invasive Chirurgie KW - Biomechanik Y1 - 2014 U6 - https://doi.org/10.1002/jor.22710 VL - 32 IS - 12 SP - 1680 EP - 1687 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Weber, Tim A1 - Kennedy, O. T1 - Musculoskeletal modeling for hip replacement outcome analyses and other applications JF - The Journal of the American Academy of Orthopaedic Surgeons KW - Hüftgelenkprothese KW - Bewegungsapparat KW - Simulation Y1 - 2014 U6 - https://doi.org/10.5435/JAAOS-22-04-268 VL - 22 IS - 4 SP - 268 EP - 269 ER - TY - JOUR A1 - Penzkofer, Rainer A1 - Barnsteiner, K. A1 - Dendorfer, Sebastian T1 - The influence of age, shoe type and kicking direction on the severity of head trauma JF - Journal of Forensic Biomechanics N2 - In the last few years, increasingly kicks to the head were observed as a criminal offense. This study examined the influence of age, shoe type and kicking direction on the severity of head trauma. Male test persons were divided into two groups “Old” and “Young”. Both groups were equipped with light sneakers and combat boots. A standard laboratory crash dummy was used to simulate the victim’s body. First, the dummy’s head, free floating above the ground, was kicked vertically. Second, the dummy’s head was kicked horizontally. Established injury criteria were used to quantify the injury risk. No influence concerning the type of foot wear and no difference between the groups “Old” and “Young” could be found. For all analyses, kicking vertically generally lead to a higher risk for the subject compared to kicking horizontally. In this study, only the integral effect of the kicks could be analyzed. A detailed injury pattern cannot directly be derived from the data. Nevertheless, the presented data show the massive potential of injuries associated with head kicks. KW - Head trauma KW - Biomechanics KW - Kicks KW - Kopfverletzung KW - Schädel-Hirn-Trauma KW - Einflussgröße Y1 - 2014 UR - https://www.longdom.org/open-access/the-influence-of-age-shoe-type-and-kicking-direction-on-the-severity-of-head-trauma-2090-2697-1000116.pdf U6 - https://doi.org/10.4172/2090-2697.1000116 VL - 5 IS - 1 ER - TY - JOUR A1 - Zellner, Johannes A1 - Hierl, Katja A1 - Mueller, Michael A1 - Pfeifer, Christian A1 - Berner, Arne A1 - Dienstknecht, Thomas A1 - Krutsch, Werner A1 - Geis, Sebastian A1 - Gehmert, Sebastian A1 - Kujat, Richard A1 - Dendorfer, Sebastian A1 - Prantl, Lukas A1 - Nerlich, Michael A1 - Angele, Peter ED - Gilbert, Jeremy T1 - Stem cell-based tissue-engineering for treatment of meniscal tears in the avascular zone JF - Journal of Biomedical Materials Research Part B Applied Biomaterials N2 - Meniscal tears in the avascular zone have a poor self-healing potential, however partial meniscectomy predisposes the knee for early osteoarthritis. Tissue engineering with mesenchymal stem cells and a hyaluronan collagen based scaffold is a promising approach to repair meniscal tears in the avascular zone. 4 mm longitudinal meniscal tears in the avascular zone of lateral menisci of New Zealand White Rabbits were performed. The defect was left empty, sutured with a 5-0 suture or filled with a hyaluronan/collagen composite matrix without cells, with platelet rich plasma or with autologous mesenchymal stem cells. Matrices with stem cells were in part precultured in chondrogenic medium for 14 days prior to the implantation. Menisci were harvested at 6 and 12 weeks. The developed repair tissue was analyzed macroscopically, histologically and biomechanically. Untreated defects, defects treated with suture alone, with cell-free or with platelet rich plasma seeded implants showed a muted fibrous healing response. The implantation of stem cell-matrix constructs initiated fibrocartilage-like repair tissue, with better integration and biomechanical properties in the precultured stem cell-matrix group. A hyaluronan-collagen based composite scaffold seeded with mesenchymal stem cells is more effective in the repair avascular meniscal tear with stable meniscus-like tissue and to restore the native meniscus. KW - biomechanics KW - meniscus KW - scaffolds KW - stem cells KW - tissue engineering KW - Meniskusschaden KW - Tissue Engineering KW - Mesenchymzelle KW - Hyaluronsäure Y1 - 2013 U6 - https://doi.org/10.1002/jbm.b.32922 VL - 101 IS - 7 SP - 1133 EP - 1142 ER - TY - CHAP A1 - Weber, Tim A. A1 - Dendorfer, Sebastian A1 - Dullien, Silvia A1 - Grifka, Joachim A1 - Verkerke, Gijsbertus Jacob A1 - Renkawitz, Tobias T1 - Measuring functional outcome after total hip replacement with subject-specific hip joint loading T2 - Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine N2 - Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement. A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg. The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced. The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement. KW - total hip replacement KW - subject-specific musculoskeletal modeling KW - functional outcome KW - force pathways KW - force angles KW - critical hip joint loading KW - rim loading KW - cup loading KW - Hüftgelenkprothese KW - Biomechanik KW - Lastverteilung KW - Ganganalyse KW - Simulation Y1 - 2012 U6 - https://doi.org/10.1177/0954411912447728 VL - 226 IS - 12 SP - 939 EP - 946 ER - TY - JOUR A1 - Renkawitz, Tobias A1 - Dendorfer, Sebastian T1 - Orthopedic navigation technology and biomechanical evaluation for total hip replacement JF - Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine KW - Hüftgelenkprothese KW - Orthopädische Chirurgie KW - Computerunterstütztes Verfahren KW - Biomechanische Analyse Y1 - 2012 U6 - https://doi.org/10.1177/0954411912458746 VL - 226 IS - 12 SP - 897 EP - 898 ER - TY - JOUR A1 - Neuschaefer-Rube, C. A1 - Lehmann, Thomas M. A1 - Palm, Christoph A1 - Bredno, J. A1 - Klajman, S. A1 - Spitzer, Klaus T1 - 3D-Visualisierung glottaler Abduktionsbewegungen JF - Aktuelle phoniatrisch-pädaudiologische Aspekte Y1 - 2001 SN - 3-922766-76-5 VL - 2001/2002 IS - 9 SP - 58 EP - 61 PB - Median ER - TY - JOUR A1 - Ilgner, Justus F. R. A1 - Palm, Christoph A1 - Schütz, Andreas G. A1 - Spitzer, Klaus A1 - Westhofen, Martin A1 - Lehmann, Thomas M. T1 - Colour Texture Analysis for Quantitative Laryngoscopy JF - Acta Otolaryngologica N2 - Whilst considerable progress has been made in enhancing the quality of indirect laryngoscopy and image processing, the evaluation of clinical findings is still based on the clinician's judgement. The aim of this paper was to examine the feasibility of an objective computer-based method for evaluating laryngeal disease. Digitally recorded images obtained by 90 degree- and 70 degree-angled indirect rod laryngoscopy using standardized white balance values were made of 16 patients and 19 healthy subjects. The digital images were evaluated manually by the clinician based on a standardized questionnaire, and suspect lesions were marked and classified on the image. Following colour separation, normal vocal cord areas as well as suspect lesions were analyzed automatically using co-occurrence matrices, which compare colour differences between neighbouring pixels over a predefined distance. Whilst colour histograms did not provide sufficient information for distinguishing between healthy and diseased tissues, consideration of the blue content of neighbouring pixels enabled a correct classification in 81.4% of cases. If all colour channels (red, green and blue) were regarded simultaneously, the best classification correctness obtained was 77.1%. Although only a very basic classification differentiating between healthy and diseased tissue was attempted, the results showed progress compared to grey-scale histograms, which have been evaluated before. The results document a first step towards an objective, machine-based classification of laryngeal images, which could provide the basis for further development of an expert system for use in indirect laryngoscopy. KW - diagnostic laryngoscopy KW - electronic imaging KW - endoscopy KW - neoplastic larynx disease Y1 - 2003 U6 - https://doi.org/10.1080/00016480310000412 VL - 123 SP - 730 EP - 734 ER - TY - CHAP A1 - Palm, Christoph A1 - Lehmann, Thomas M. A1 - Bredno, J. A1 - Neuschaefer-Rube, C. A1 - Klajman, S. A1 - Spitzer, Klaus T1 - Automated Analysis of Stroboscopic Image Sequences by Vibration Profiles T2 - Advances in Quantitative Laryngoscopy, Voice and Speech Research, Procs. 5th International Workshop N2 - A method for automated segmentation of vocal cords in stroboscopic video sequences is presented. In contrast to earlier approaches, the inner and outer contours of the vocal cords are independently delineated. Automatic segmentation of the low contrasted images is carried out by connecting the shape constraint of a point distribution model to a multi-channel regionbased balloon model. This enables us to robustly compute a vibration profile that is used as a new diagnostic tool to visualize several vibration parameters in only one graphic. The vibration profiles are studied in two cases: one physiological vibration and one functional pathology. KW - Vibration Profile KW - Stroboscopic Images KW - Contour Detection KW - Balloon Model KW - Point Distribution Model Y1 - 2001 UR - https://www.researchgate.net/publication/242439073_Automated_Analysis_of_Stroboscopic_Image_Sequences_by_Vibration_Profiles ER - TY - CHAP A1 - Pietrzyk, Uwe A1 - Palm, Christoph A1 - Beyer, Thomas T1 - Investigation of fusion strategies of multi-modality images T2 - IEEE Nuclear Science Symposium Conference Record N2 - Presenting images from different modalities seems to be a trivial task considering the challenges to obtain registered images as a pre-requisite for image fusion. In combined tomographs like PET/CT, image registration is intrinsic. However, informative image fusion mandates careful preparation owing to the large amount of information that is presented to the observer. In complex imaging situations it is required to provide tools that are easy to handle and still powerful enough to help the observer discriminating important details from background patterns. We investigated several options for color tables applied to brain and non-brain images obtained with PET, MRI and CT. KW - Positron emission tomography KW - Biomedical imaging KW - Medical diagnostic imaging KW - Image fusion KW - Computed tomography KW - Image registration KW - Visualization KW - Table lookup KW - Humans Y1 - 2004 U6 - https://doi.org/10.1109/NSSMIC.2004.1462740 VL - 4 SP - 2399 EP - 2401 ER - TY - CHAP A1 - Pietrzyk, Uwe A1 - Bauer, Dagmar A1 - Vieten, Andrea A1 - Bauer, Andreas A1 - Langen, Karl-Josef A1 - Zilles, Karl A1 - Palm, Christoph T1 - Creating consistent 3D multi-modality data sets from autoradiographic and histological images of the rat brain T2 - IEEE Nuclear Science Symposium Conference Record N2 - Volumetric representations of autoradiographic and histological images gain ever more interest as a base to interpret data obtained with /spl mu/-imaging devices like microPET. Beyond supporting spatial orientation within rat brains especially autoradiographic images may serve as a base to quantitatively evaluate the complex uptake patterns of microPET studies with receptor ligands or tumor tracers. They may also serve for the development of rat brain atlases or data models, which can be explored during further image analysis or simulation studies. In all cases a consistent spatial representation of the rat brain, i.e. its anatomy and the corresponding quantitative uptake pattern, is required. This includes both, a restacking of the individual two-dimensional images and the exact registration of the respective volumes. We propose strategies how these volumes can be created in a consistent way and trying to limit the requirements on the circumstances during data acquisition, i.e. being independent from other sources like video imaging of the block face prior to cutting or high resolution micro-X-ray CT or micro MRI. KW - Neoplasms KW - Data models KW - Image analysis KW - Brain modeling KW - Analytical models KW - Anatomy KW - Data acquisition KW - High-resolution imaging KW - Image resolution KW - Computed tomography Y1 - 2004 U6 - https://doi.org/10.1109/NSSMIC.2004.1466754 VL - 6 SP - 4001 EP - 4003 ER - TY - JOUR A1 - Palm, Christoph T1 - Color Texture Classification by Integrative Co-Occurrence Matrices JF - Pattern Recognition N2 - Integrative Co-occurrence matrices are introduced as novel features for color texture classification. The extended Co-occurrence notation allows the comparison between integrative and parallel color texture concepts. The information profit of the new matrices is shown quantitatively using the Kolmogorov distance and by extensive classification experiments on two datasets. Applying them to the RGB and the LUV color space the combined color and intensity textures are studied and the existence of intensity independent pure color patterns is demonstrated. The results are compared with two baselines: gray-scale texture analysis and color histogram analysis. The novel features improve the classification results up to 20% and 32% for the first and second baseline, respectively. KW - Color texture KW - Co-occurrence matrix KW - Integrative features KW - KolmogKorov distance KW - Image classification Y1 - 2004 U6 - https://doi.org/10.1016/j.patcog.2003.09.010 VL - 37 IS - 5 SP - 965 EP - 976 ER - TY - CHAP A1 - Pietrzyk, Uwe A1 - Palm, Christoph A1 - Beyer, Thomas T1 - Fusion strategies in multi-modality imaging T2 - Medical Physics, Vol 2. Proceedings of the jointly held Congresses: ICMP 2005, 14th International Conference of Medical Physics of the International Organization for Medical Physics (IOMP), the European Federation of Organizations in Medical Physics (EFOMP) and the German Society of Medical Physics (DGMP) ; BMT 2005, 39th Annual Congress of the German Society for Biomedical Engineering (DGBMT) within VDE ; 14th - 17th September 2005, Nuremberg, Germany KW - Bildgebendes Verfahren KW - Registrierung Y1 - 2005 SP - 1446 EP - 1447 ER - TY - CHAP A1 - Palm, Christoph A1 - Dehnhardt, Markus A1 - Vieten, Andrea A1 - Pietrzyk, Uwe T1 - 3D rat brain tumor reconstruction T2 - Biomedizinische Technik KW - Dreidimensionale Rekonstruktion KW - Hirntumor Y1 - 2005 VL - 50 IS - Suppl. 1, Part 1 SP - 597 EP - 598 ER - TY - JOUR A1 - Wiesent, Lisa A1 - Schultheiss, Ulrich A1 - Schmid, Christof A1 - Schratzenstaller, Thomas A1 - Nonn, Aida T1 - Experimentally validated simulation of coronary stents considering different dogboning ratios and asymmetric stent positioning JF - PlOS One N2 - In-stent restenosis remains a major problem of arteriosclerosis treatment by stenting. Expansion-optimized stents could reduce this problem. With numerical simulations, stent designs/ expansion behaviours can be effectively analyzed. For reasons of efficiency, simplified models of balloon-expandable stents are often used, but their accuracy must be challenged due to insufficient experimental validation. In this work, a realistic stent life-cycle simulation has been performed including balloon folding, stent crimping and free expansion of the balloon-stent-system. The successful simulation and validation of two stent designs with homogenous and heterogeneous stent stiffness and an asymmetrically positioned stent on the balloon catheter confirm the universal applicability of the simulation approach. Dogboning ratio, as well as the final dimensions of the folded balloon, the crimped and expanded stent, correspond well to the experimental dimensions with only slight deviations. In contrast to the detailed stent life-cycle simulation, a displacement-controlled simulation can not predict the transient stent expansion, but is suitable to reproduce the final expanded stent shape and the associated stress states. The detailed stent life-cycle simulation is thus essential for stent expansion analysis/optimization, whereas for reasons of computational efficiency, the displacement-controlled approach can be considered in the context of pure stress analysis. KW - Catheters KW - Coronary stenting KW - Deformation KW - Stent implantation KW - Stiffness KW - Stent KW - Ballondilatation KW - Numerische Strömungssimulation Y1 - 2019 U6 - https://doi.org/10.1371/journal.pone.0224026 VL - 14 IS - 10 SP - 1 EP - 25 PB - PLOS ER - TY - JOUR A1 - Geith, Markus A. A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - Biomechanical and structural quantification of vascular damage: A unique investigation of stent implantation JF - Artery Research Y1 - 2017 U6 - https://doi.org/10.1016/j.artres.2017.10.025 VL - 20 IS - Issue C SP - 50 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Taylor, David A1 - Hammer, Joachim T1 - Anisotropy of the fatigue behaviour of cancellous bone JF - Journal of Biomechanics N2 - The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions which are not aligned with the main physiological axis remains unclear. Furthermore site and species dependent relationships are not well described. In this study five different groups of trabecular bone, defined in terms of orientation, species and site were exposed to cyclic compression. In total, 108 fatigue tests were analysed. The lifetimes were found to decrease drastically when off-axis loads were applied. Additionally, species and site strongly affect fatigue lifetimes. Strains at failure were also found to be a function of orientation. KW - Ermüdung KW - Knochen KW - Spongiosa KW - Anisotropie Y1 - 2008 U6 - https://doi.org/10.1016/j.jbiomech.2007.09.037 VL - 41 IS - 3 SP - 636 EP - 641 ER - TY - JOUR A1 - Pfeifer, Christian A1 - Müller, Michael A1 - Prantl, Lukas A1 - Berner, Arne A1 - Dendorfer, Sebastian A1 - Englert, Carsten T1 - Cartilage labelling for mechanical testing in T-peel configuration JF - International Orthopaedics N2 - PURPOSE: The purpose of this study was to find a suitable method of labelling cartilage samples for the measurement of distraction distances in biomechanical testing. METHODS: Samples of bovine cartilage were labelled using five different methods: hydroquinone and silver nitrate (AgNO3), potassium permanganate (KMnO4) with sodium thiosulphate (Na2S2O3), India ink, heat, and laser energy. After the labelling, we analysed the cartilage samples with regard to cytotoxity by histochemical staining with ethidiumbromide homodimer (EthD-1) and calcein AM. Furthermore, we tested cartilages labelled with India ink and heat in a T-peel test configuration to analyse possible changes in the mechanical behaviour between marked and unlabelled samples. RESULTS: Only the labelling methods with Indian ink or a heated needle showed acceptable results in the cytotoxity test with regard to labelling persistence, accuracy, and the influence on consistency and viability of the chondrocytes. In the biomechanical T-peel configuration, heat-labelled samples collapsed significantly earlier than unlabelled samples. CONCLUSION: Labelling bovine cartilage samples with Indian ink in biomechanical testing is a reliable, accurate, inexpensive, and easy-to-perform method. This labelling method influenced neither the biomechanical behaviour nor the viability of the tissue compared to untreated bovine cartilage. KW - Bovine cartilage KW - Cartilage samples KW - Indian ink KW - T-peel configuration KW - Method labeling KW - Knorpel KW - Rind KW - Kennzeichnung KW - Tinte KW - Biomechanik KW - Prüfung Y1 - 2012 U6 - https://doi.org/10.1007/s00264-011-1468-3 VL - 36 IS - 7 SP - 1493 EP - 1499 PB - Springer ER - TY - CHAP A1 - Geith, Markus A. A1 - Sommer, Gerhard A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. T1 - First Approaches in Quantifying Acute Vascular Damage due to Stenting T2 - 23rd Congress of the European Society of Biomechanics, July 2-5,2017, Seville, Spain KW - Stent KW - Implantation KW - Gefäßverletzung Y1 - 2017 ER - TY - JOUR A1 - Englert, Carsten A1 - Angele, Peter A1 - Fierlbeck, J. A1 - Dendorfer, Sebastian A1 - Schubert, T. A1 - Müller, R. A1 - Lienhard, S. A1 - Zellner, Johannes A1 - Nerlich, Michael A1 - Neumann, Carsten T1 - Conductive bone substitute material with variable antibiotic delivery JF - Der Unfallchirurg N2 - A new bone substitute, consisting of hydroxylapatite and calcium sulphate, was prepared in two formulations and analysed for its mechanical strength and antibiotic elution.The bone substitute PerOssal has osteoconductive and degradable properties. The material has a built-in capillary structure, which results in an immediate fluid uptake. Antibiotics absorbed to the bone substitute resulted in a prolonged release rate. Mechanical strength was investigated by an unconfined compression test up to failure under both wet and dry conditions for both formulations of the bone substitute. Antibiotic release was analysed microbiologically for two antibiotics, vancomycin and gentamicin, over an elution period of 10 days using the agar diffusion method.The drug release analysis resulted in a prolonged release rate of both antibiotics over 10 days. In vitro the amount of gentamicin and vancomycin eluted at day 10. From one pellet still exceeded the minimal inhibitory concentration of most aetiologically important pathogens. Formulation two of the present bone substitute is significantly harder in both wet and dry conditions when compared to formulation one. Both formulations lose strength in the wet condition relative to their performance in the dry condition. However, formulation two is as hard under wet conditions as formulation one is when dry.PerOssal is a suitable new degradable osteoconductive bone substitute that can be loaded with antibiotic solutions, which are released in effective doses over 10 days. The mechanical strength of PerOssal is sufficient to support cancellous bone defects in non-weight-bearing areas or in combination with osteosynthesis. KW - Knochenersatz KW - Leitfähgkeit KW - Antibiotika KW - Biomechanik KW - Bone substitute materials KW - Osteoconductive KW - Osteomyelitis KW - Multiresistant KW - Biomechanics Y1 - 2007 U6 - https://doi.org/10.1007/s00113-007-1229-3 VL - 110 IS - 5 SP - 408 EP - 413 PB - Springer ER - TY - JOUR A1 - Lenich, Andreas A1 - Bachmeier, S. A1 - Dendorfer, Sebastian A1 - Mayr, E. A1 - Nerlich, Michael A1 - Füchtmeier, Bernd T1 - Development of a test system to analyze different hip fracture osteosyntheses under simulated walking JF - Biomedizinische Technik. Biomedical engineering N2 - The mechanical complications of osteosyntheses after hip fractures are previously investigated by mostly static or dynamic uniaxial loading test systems. However, the physiologic loading of the hip joint during a normal gait is a multiplanar, dynamic movement. Therefore, we constructed a system to test osteosyntheses for hip fractures under physiologic multiplanar loading representative of normal gait. To evaluate the testing system, 12 femora pairs were tested under 25,000 cycles with two standard osteosyntheses (Proximal Femoral Nail Antirotation/Gamma3 Nail). For angular movement, the varus collapse to cut out (∝CO) (∝CO=4.8°±2.1° for blade and ∝CO=7.8°±3.8° for screw) was the dominant failure mode, and only slight rotational angle shifts (∝Rot) (∝Rot=1.7°±0.4° for blade and ∝Rot=2.4°±0.3° for screw) of the femoral head around the implant axis were observed. Angular displacements in varus direction and rotation were higher in specimens reinforced with screws. Hence, the cut out model and the migration directions showed a distinction between helical blade and hip screw. However, there were no significant differences between the different implants. The new setup is able to create clinical failures and allows to give evidence about the anchorage stability of different implant types under dynamic gait motion pattern. KW - biomechanical implant test KW - dynamic multiplanar loading KW - hip fractureg KW - implant migration KW - patient specific loading KW - Hüftgelenk KW - Knochenbruch KW - Osteosynthese KW - Bewegungsanalyse KW - Simulation Y1 - 2012 U6 - https://doi.org/10.1515/bmt-2011-0999 VL - 57 IS - 2 SP - 113 EP - 119 ER - TY - JOUR A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Hammer, Joachim T1 - Fatigue damage in cancellous bone: an experimental approach from continuum to micro scale JF - Journal of the Mechanical Behavior of Biomedical Materials N2 - Repeated loadings may cause fatigue fractures in bony structures. Even if these failure types are known, data for trabecular bone exposed to cyclic loading are still insufficient as the majority of fatigue analyses on bone concentrate on cortical structures. Despite its highly anisotropic and inhomogeneous structure, trabecular bone is treated with continuum approaches in fatigue analyses. The underlying deformation and damage mechanism within trabecular specimens are not yet sufficiently investigated. In the present study different types of trabecular bone were loaded in monotonic and cyclic compression. In addition to the measurement of integral specimen deformations, optical deformation analysis was employed in order to obtain strain distributions at different scale levels, from the specimens' surface to the trabeculae level. These measurements allowed for the possibility of linking the macroscopic and microscopic mechanical behaviour of cancellous bone. Deformations were found to be highly inhomogeneous across the specimen. Furthermore strains were found to already localise at very low load levels and after few load cycles. Microcracks in individual trabeculae were induced in the very early stage of cyclic testing. The results provide evidence of the capability of the method to supply essential data on the failure behaviour of individual trabeculae in future studies. KW - Knochen KW - Spongiosa KW - Ermüdungsbruch KW - Fatigue KW - Cancellous bone KW - Deformation behaviour KW - Damage KW - Measurement and testing KW - Mechanical behaviour Y1 - 2009 U6 - https://doi.org/10.1016/j.jmbbm.2008.03.003 VL - 2 IS - 1 SP - 113 EP - 119 ER - TY - CHAP A1 - Dendorfer, Sebastian A1 - Maier, Hans Jürgen A1 - Hammer, Joachim T1 - How do age and anisotropy affect the fatigue behaviour of cancellous bone? T2 - Medicine Meets Engineering N2 - The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions not aligned with the main physiological axis remains unclear. Furthermore age effects on the fatigue behaviour are not well described. In the present study, different groups of human vertebral cancellous bone were exposed to cyclic compression. The inital modulus and therefore lifetimes were found to be highly dependent on age. The decrease in both with increasing age was much more pronounced in specimens which were not aligned with the main physiological axis. This implies that old bone is much more sensitive to (cyclic) failure loads in general but particularly to loads which are not coincident with the physiological main axis. KW - Knochenbruch KW - Spongiosa KW - Alter KW - Anisotropie Y1 - 2008 SP - 68 EP - 74 PB - IOS Press ER - TY - JOUR A1 - Hoenicka, Markus A1 - Lehle, Karla A1 - Jacobs, V. R. A1 - Dendorfer, Sebastian A1 - Kostorz, A. A1 - Schmid, F. X. A1 - Birnbaum, D. E. T1 - Mechanical and seeding properties of human umbilical vein – a potential scaffold for a tissue-engineered vessel graft JF - The Thoracic and Cardiovascular Surgeon N2 - Objectives: The mechanical properties and seeding with endothelial cells were investigated in fresh and cryopreserved human umbilical vein. Methods: Human umbilical veins (HUV) were frozen in Euro-Collins/1M DMSO at –1°C/min and stored in liquid nitrogen. Stress-strain relationships of fresh and thawed veins were determined in an uniaxial tension-testing rig. HUV endothelial cells (HUVEC) were seeded onto denuded HUV under static conditions and grown for 3d. Luminal surfaces were analyzed by scanning electron microscopy. Calcein-stained cells were seeded hyperconfluently to determine the cell retention capacity of fresh and cryopreserved veins. Results: The stress-strain relationships of HUV followed a biphasic pattern typical for natural vessels. Neither the failure stress (2.71±0.36 vs. 3.25±0.97 N, n=3) nor the displacement required to achieve failure (9.73±0.9 vs. 7.43±2.07mm, n=3) were altered by cryopreservation. The burst pressure was estimated as approx. 1000mm Hg within the limitations of the uniaxial model. HUVEC seeded onto denuded HUV formed patches (at 9E3 cells per cm2) or an almost confluent endothelium (at 3E4 cells per cm2) within three days. The capacity to retain seeded HUVEC of denuded HUV was not altered by cryopreservation (1.15±0.08E5 vs. 1.26±0.14E5 cells per cm2, n=6). Conclusions: The burst pressure of HUV seems to be sufficiently high for the human arterial circulation and is not altered by cryopreservation. HUVEC can establish a confluent endothelium on denuded HUV. Therefore HUV appears to be a suitable storable scaffold for vascular tissue engineering. KW - Nabelvene KW - Tissue Engineering Y1 - 2007 U6 - https://doi.org/10.1055/s-2007-967592 VL - 55 IS - S 1 SP - P_37 PB - Thieme ER - TY - JOUR A1 - Roldán, J.C. A1 - Moralis, A. A1 - Dendorfer, Sebastian A1 - Witte, J. A1 - Reicheneder, C. T1 - Controlled central advancement of the midface after Le Fort III osteotomy by a 3-point skeletal anchorage JF - The Journal of craniofacial surgery N2 - A 3-point skeletal anchorage with taping screws for distraction osteogenesis after a Le Fort III osteotomy was applied for the first time in a severely mentally impaired patient where intraoral devices had to be avoided. All 3-force application points included the center of resistance, which allowed an optimal control on the resulting moment. A novel device for skeletal long-term retention into the nasal dorsum prevented a relapse, whereas adjustment of the midface position was observed. Fusioned three-dimensional computed tomography analysis revealed real movements not accessible by a conventional cephalometry. KW - Mund-Kiefer-Gesichts-Chirurgie KW - Le Fort III KW - distraction KW - vector KW - anchorage KW - three-dimensional computed tomography analysis KW - Distraktion KW - Knochenbildung KW - Osteotomie KW - Dreidimensionale Bildverarbeitung KW - Computertomografie Y1 - 2011 U6 - https://doi.org/10.1097/SCS.0b013e318231fc8d VL - 22 IS - 6 SP - 2384 EP - 2386 ER - TY - GEN ED - Hammer, Joachim ED - Nerlich, Michael ED - Dendorfer, Sebastian T1 - Medicine Meets Engineering: Proceedings of the 2nd Conference on Applied Biomechanics Regensburg N2 - Biomedical Engineering is defined as the science that integrates medical and engineering sciences to improve diagnosis and treatment of patients. Only by this integration progress can be achieved. Both medical and engineering sciences comprise a huge diversity in topics, so it is imaginable that Biomedical Engineering, combining these two science areas, is even more huge. Thanks to this megadisciplinary approach many breakthroughs can be achieved. More and more research groups realize this and start new research projects, which results in a rapid increase in knowledge in Biomedical Engineering. This will only benefit the main goal of Biomedical Engineering; improving diagnosis and treatment of patients when it is spread and applied. The 2nd Regensburg Applied Biomechanics conference is special in that it realized both the distribution of new knowledge and the essential integration of medical and engineering specialists. The conference dealt with the latest results in applied biomechanics, ranging from fundamental bone strength properties via bone remodeling phenomena to new implants that replace lost human functions. Also new research areas like robot surgery and tissue engineering were discussed. KW - Biomechanik Y1 - 2008 SN - 978-1586038281 PB - IOS Press, US ET - 1. Aufl. ER - TY - GEN A1 - Geith, Markus A. A1 - Swidergal, Krzysztof A1 - Schratzenstaller, Thomas A1 - Holzapfel, Gerhard A. A1 - Wagner, Marcus T1 - Numerical analysis of stent delivery systems during pre- and intraoperative processes T2 - 15. Deutsches LS-DYNA Forum, 15.-17.10.2018, Bamberg Y1 - 2018 UR - https://www.researchgate.net/publication/335260823_Numerical_analysis_of_stent_delivery_systems_during_pre-_and_intraoperative_processes ER - TY - JOUR A1 - Geith, Markus A. A1 - Swidergal, Krzysztof A1 - Hochholdinger, Bernd A1 - Schratzenstaller, Thomas A1 - Wagner, Marcus A1 - Holzapfel, Gerhard A. T1 - On the importance of modeling balloon folding, pleating, and stent crimping: An FE study comparing experimental inflation tests JF - International Journal for Numerical Methods in Biomedical Engineering N2 - Finite element (FE)–based studies of preoperative processes such as folding,pleating, and stent crimping with a comparison with experimental inflation tests are not yet available. Therefore, a novel workflow is presented in which residual stresses of balloon folding and pleating, as well as stent crimping, and the geometries of all contact partners were ultimately implemented in an FE code to simulate stent expansion by using an implicit solver. The numerical results demonstrate that the incorporation of residual stresses and strains experienced during the production step significantly increased the accuracy of the subsequent simulations, especially of the stent expansion model. During the preoperative processes, stresses inside the membrane and the stent material also reached a rather high level. Hence, there can be no presumption that balloon catheters or stents are undamaged before the actual surgery. The implementation of the realistic geometry, in particular the balloon tapers, and the blades of the process devices improved the simulation of the expansion mech-anisms, such as dogboning, concave bending, or overexpansion of stent cells. This study shows that implicit solvers are able to precisely simulate the mentioned preoperative processes and the stent expansion procedure without a preceding manipulation of the simulation time or physical mass. KW - Catheter KW - Coronary KW - Crimping KW - Finite element KW - Stent KW - Stent KW - Implantation KW - Simulation KW - Finite-Elemente-Methode Y1 - 2019 U6 - https://doi.org/10.1002/cnm.3249 N1 - This study was funded by the Bavarian Research Foundation within the project “PIZ‐225‐18” VL - 35 IS - 11 PB - Wiley ER -