Mathias Hofer

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INTRODUCTION The question about the most appropriate non-invasive method for detecting a renal artery stenosis (RAS) when comparing contrast enhanced magnetic resonance angiography (MRA) and color Doppler sonography (CDS) is still under discussion. Therefore we conducted a prospective study in order to evaluate both methods as compared to digital(More)
PURPOSE To assess time-of-flight MR angiography that uses magnetization transfer contrast (MTC) pulses, tilted optimized nonsaturating excitation (TONE), and a 256 x 512 image matrix for the detection of small intracranial arteries and for the detection and quantification of intracranial arterial stenoocclusive disease. METHODS To assess anatomic(More)
BACKGROUND With the application of optical navigation systems an interruption of the line of sight (LOS) between navigation camera and the patient/instrument can occur. The goal of this work is the clinical evaluation of a newly developed system for automatic adjusting of an optical navigation camera (Navigation Camera Assistant, NCA). NCA is a miniature(More)
PROBLEM The aim of this study is to proof the clinical efficiency by using a modern navigation system for Functional Endoscopic Sinus Surgery (FESS). MATERIAL AND METHODS An optical navigation system was used in clinical routine of 300 patients. Two groups with 150 patients each were examined. Group A was treated with navigation assistance (Karl Storz(More)
The aim of this study is the evaluation of a navigation system (NaviBase) for ENT surgery. For this purpose, a new methodology for the evaluation of surgical and ergonomic system properties has been developed. The practicability of the evaluation instruments will be examined using the example of the overall assessment of the system in comparison with the(More)
Samples of exhaled breath and breath condensate were collected from 20 feral pigeons (Columba livia) while they were anaesthetised and intubated, and when they were kept unanaesthetised in an acrylic box. Samples were also collected from six chickens (Gallus domesticus) while they were kept in an acrylic box. The samples were analysed for pH, nitric oxide(More)
OBJECTIVE Signal loss due to poststenotic turbulence is one remaining limitation in the clinical use of MRA. The objective of this study was to determine the factors influencing poststenotic signal loss (PSL) in a stenotic tube system. MATERIALS AND METHODS With use of a two-dimensional gradient echo sequence (FLASH), the influence of (a) the degree of(More)
Flexible endoscopes are used in ENT surgery for examination tasks in cases wherever rigid endoscopes are unsuitable to reach certain positions in the nasal cavity. Until today they are steered by hand and no robotized system has been put into clinical practice. One qualification a robot manipulator system has to fulfill to be accepted is not to create new(More)
BACKGROUND This study examines the feasibility of a navigation-controlled (NC) drill for surgery on the petrosal bone in an experimental environment. According to the principle of NC, the drill is to be switched off automatically once the borders of the workspace are exceeded during a mastoidectomy. MATERIALS AND METHODS The registration is based on an(More)
Die Zielstellung dieser Arbeit ist die Erweiterung der bisherigen Instrumentennavigation um eine Funktion der Kollisionswarnung mit Hilfe einer zusätzlichen Abstandsanzeige und einer Warnsystematik. Das Kollisionswarnsystem (DCS) ist eine Erweiterung eines optoelektrischen Navigationssystems (NPU, Fa. Karl Storz, Tuttlingen). Die Messungen zur(More)