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Dive into the research topics where Sophie Krüger is active.

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Featured researches published by Sophie Krüger.


medical image computing and computer assisted intervention | 2003

A System for Real-Time Endoscopic Image Enhancement

Florian Vogt; Sophie Krüger; Heinrich Niemann; Christoph Schick

During endoscopic operations the surgeon works without direct visual contact to the operation area. The image of the operation situs is displayed on a monitor. Currently, only hardware based image enhancement methods are used (e. g., white balance) and often only once at the beginning of an operation. In this contribution we describe a system for real-time endoscopic image enhancement: a typical video-endoscopic system was extended by a computer and a second monitor. Thus the enhanced and the original image can be displayed at the same time. The implemented image enhancement methods (temporal filtering, undistortion and color normalization) were evaluated by 14 surgeons and the results showed that the enhanced images were preferred. The system was already used during a real operation.


Clinical Autonomic Research | 2003

Differential effects of surgical sympathetic block at the T2 and T4 level on vasoconstrictor function.

Sophie Krüger; Kerstin S. Fronek; Martin Schmelz; Thomas Horbach; Werner Hohenberger; Christoph Schick

Abstract.Endoscopic sympathetic block (ESB) is used as a treatment of excessive palmar sweating. In a prospective study we compared the effect of ESB at the level of the second (T2) and fourth thoracic ganglion (T4) on vasoconstriction and sweating of the hands. Sympathetic vasoconstriction was measured by computerassisted infrared thermography following ice water immersion of the hands in 22 hyperhidrosis patients before, two days and 3 months post op. In addition, palmar sweating before and 3 months post op was assessed by sudometry. After ESB the rewarming was accelerated in both T2 and T4 patients, but was significantly slower in the T4 group. Three months postoperatively rewarming had returned to the preoperative pattern in T4 patients but was still significantly faster in the T2 group. These effects were more pronounced in the fingertips than the hand dorsum. Sudomotor function was blocked in all T2 patients but had relapsed in 2 patients in the T4 group. Two T4 patients had not shown an effect on sudomotor function postoperatively. The normalization of rewarming kinetics may be explained by remaining fibers, denervation hypersensitivity or stimulation of catecholamine receptors, or neuronal reorganization. The effect of ESB T4 on sudomotor function has to be proven.


Clinical Autonomic Research | 2003

Effects of gender and level of surgical sympathetic block on vasoconstrictor function

Kerstin S. Fronek; Martin Schmelz; Sophie Krüger; Werner Hohenberger; Christoph Schick

Abstract.Interruption of sympathetic outflow by surgical sympathetic block has been used to treat hyperhidrosis for decades. In this study the effect of gender and the level of sympathetic block (T2 vs. T3) on the rewarming kinetics following ice water immersion were assessed in a prospective study on 60 hyperhidrosis patients before, 2 days, and 3 months postoperatively. Rewarming kinetics following endoscopic sympathetic block (ESB) was massively enhanced 2 days post-operatively, but had returned to pre-operative conditions at the 3 month follow-up for ESB at level T3. ESB at level T2 provoked significantly faster rewarming as compared to T3 at the 2 day and 3 month follow-up. Independent of the level of ESB, there was a slower rewarming in women already pre-operatively. This gender difference was clearly reduced at the 2 day follow-up, but had increased again at the 3 month follow-up. There was no correlation between the rewarming kinetics of the fingertips and palmar sweating. We conclude that for the sympathetic vasoconstriction of the fingertips the sympathetic ganglion T2 is crucial. Gender differences have to be taken into account when assessing effect of ESB by cold induced vasoconstriction. It remains to be established whether the quantification of vasoconstriction has some predictive value for the long-term prognosis of sudomotor blockade.


Pain Medicine | 2010

Thoracoscopic sympathectomy at the T2 or T3 level facilitates bradykinin-induced protein extravasation in human forearm skin.

Stefan Leis; Nicola Meyer; Andreas Bickel; Christoph Schick; Sophie Krüger; Martin Schmelz; Frank Birklein

BACKGROUND The endogenous peptide bradykinin (BK) is an inflammatory mediator that induces nociceptor activation and sensitization as well as protein extravasation and vasodilation. OBJECTIVE To test the hypothesis if sympathectomy affects BK-induced inflammation in humans. METHODS Dermal microdialysis was employed on the volar forearm in 10 patients (21-41 years) with regional hyperhidrosis before and three months after preganglionic endoscopic transthoracic sympathetic clipping (ETSC) at the T2 or T3 level and in 10 healthy volunteers (22-36 years). After 60 minutes perfusion with Ringers solution microdialysis fibers were perfused with BK 10(-7) M and 10(-5) M for 30 minutes followed by 30 minutes Ringers solution again. To assess protein extravasation dialysate protein content was measured photometrically and Laser-Doppler imaging was used to quantify axonreflex vasodilation. RESULTS Baseline flux values after ETSC were higher as compared with controls and preoperative values (anova, Bonferroni post hoc test, P < 0.05), but neither BK 10(-7) M nor 10(-5) M led to significant vasodilation. Baseline dialysate protein did not significantly differ between groups. BK 10(-5) M induced protein extravasation while BK 10(-7) M was ineffective, and BK 10(-5) M induced protein extravasation was significantly enhanced after ETSC (P < 0.001). CONCLUSIONS Forearm skin perfusion is increased after ETSC on the T2 or T3 level indicating decreased sympathetic activity while BK-induced protein extravasation was increased. These results show that preganglionic sympathectomy does not diminish bradykinin-induced protein extravasation as found for postganglionic sympathectomy in rats.


Bildverarbeitung f&uuml;r die Medizin | 2005

Erweiterte Realität und 3-D Visualisierung für minimal-invasive Operationen durch Einsatz eines optischen Trackingsystems

Florian Vogt; Sophie Krüger; Marco Winter; Heinrich Niemann; Werner Hohenberger; Günther Greiner; Christoph Schick

Optische Trackingsysteme bieten derzeit die grostmogliche Genauigkeit zur Positionsbestimmung eines bewegten Objektes. Es ist daher nahe liegend ein solches System zur Bestimmung der Endoskopposition in der minimal-invasiven Chirurgie einzusetzen, um den Operateur durch ein dreidimensionales Modell des Operationsgebietes (und damit die Moglichkeit der dreidimensionalen Betrachtung) sowie erweiterte Realitat zu unterstutzen. Der Einsatz von optischen Trackingsystemen fur diese Zwecke wurde bisher nicht untersucht. Erstmalig wird in diesem Beitrag eine Methode zur markerlosen Registrierung eines Endoskops mit CT/MR Daten vorgestellt. Die entwickelten Verfahren benotigen nur wenige Minuten Rechenzeit und sind daher fur den Einsatz im Operationssaal geeignet.


Bildverarbeitung f&uuml;r die Medizin | 2003

Endoskopische Lichtfelder mit einem kameraführenden Roboter

Florian Vogt; Sophie Krüger; Dietrich Paulus; Heinrich Niemann; Werner Hohenberger; Christoph Schick

In diesem Beitrag beschreiben wir die Erzeugung endoskopischer Lichtfelder mit Hilfe eines kamerafuhrenden Roboterarms, mit dem die Position und Orientierung des Endoskops berechnet wird. Das vorgestellte Verfahren wird mit dem herkommlichen Verfahren zur Erzeugung von Lichtfeldern hinsichtlich Zeit und Qualitat verglichen.


Bildverarbeitung f&uuml;r die Medizin | 2003

Evaluation der rechnergestützten Bildverbesserung in der Videoendoskopie von Körperhöhlen

Sophie Krüger; Florian Vogt; Werner Hohenberger; Dietrich Paulus; Heinrich Niemann; Christoph Schick

Bei minimal-invasiven chirurgischen Eingriffen betrachtet der Operateur derzeit auf seinem Video-Monitor direkt die aufgenommenen, unveranderten Endoskopiebilder aus dem Operationsfeld. Die im Operationsverlauf typischerweise auftretende Verschlechterung der anfanglich guten Bildqualitat konnte bislang meist nur inadaquat und zeitraubend behoben werden. Durch rechnergestutzte Bildverbesserung im Sinne von Farbnormierung, zeitlicher Filterung und Bildentzerrung kann eine Steigerung der Bildqualitat erreicht werden. Die vorliegende Arbeit beschreibt, mit welchen Methoden der Einsatz dieser Verbesserungen in der klinischen Praxis evaluiert wird.


Visceral medicine | 2010

Unterschiede in der Instrumenten-und Ausstattungswahl zwischen Adipositas-Chirurgie und allgemeiner minimal invasiver Chirurgie

Thomas Horbach; Sophie Krüger

In Deutschland liegt der Anteil Übergewichtiger MÄnner (BMI >25 kg/m2) bei 66% und der Übergewichtiger Frauen bei 55%. Die Langzeiteffekte konservativer Gewichtsreduktionsprogramme sind bei Adipositas Grad II mit Begleiterkrankungen bzw. Adipositas Grad III unzureichend. Operative Interventionen haben ihre hohe EffektivitÄt bewiesen, dabei gilt die minimal invasive Technik als Standard. Die Auswahl der fÜr solche Eingriffe benÖtigten Ausstattung im OP bedarf einer Anpassung an die Übergewichtigen Patienten. Die meisten Instrumente der erweiterten minimal invasiven Chirurgie kÖnnen allerdings ohne EinschrÄnkung auch fÜr bariatrische Prozeduren eingesetzt werden. Spezialinstrumente sind fÜr einzelne Operationen erforderlich. Retraktorsysteme fÜr die Konversion zu offenen Eingriffen mÜssen vorgehalten werden.


Bildverarbeitung f&uuml;r die Medizin | 2004

Fusion von Lichtfeldern und CT-Daten für minimal-invasive Operationen*

Florian Vogt; Sophie Krüger; Timo Zinßer; Tobias Maier; Heinrich Niemann; Werner Hohenberger; Christoph Schick

Voraussetzung fur eine intraoperative markerlose Registrierung und Fusion einer Lichtfeld-Visualisierung des Operationsgebietes mit CT-Daten ist die Kenntnis der Oberflachengeometrie. Dann konnen korrespondierende Punkte fur die Registrierung ausgewahlt werden. In diesem Beitrag werden unterschiedliche Methoden zur Rekonstruktion der Oberflachengeometrie bei minimal-invasiven Operationen beschrieben sowie Ergebnisse zur Registrierung und Fusion eines Gallenblasen-Lichtfeldes mit einem segmentierten CT-Datensatz prasentiert.


Methods of Information in Medicine | 2004

Light Fields for Minimal Invasive Surgery Using an Endoscope Positioning Robot

Florian Vogt; Sophie Krüger; Jochen Schmidt; Dietrich Paulus; Heinrich Niemann; Werner Hohenberger; Christoph Schick

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Christoph Schick

University of Erlangen-Nuremberg

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Werner Hohenberger

University of Erlangen-Nuremberg

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Heinrich Niemann

University of Erlangen-Nuremberg

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Dietrich Paulus

University of Koblenz and Landau

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Andreas Bickel

University of Erlangen-Nuremberg

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Stefan Leis

University of Erlangen-Nuremberg

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Kerstin S. Fronek

University of Erlangen-Nuremberg

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