A novel method for real-time magnetic marker monitoring in thegastrointestinal tract

Abstract

In internal medicine, a simple method for the functional examination of thegastrointestinal tract without the risk of radiation exposure is required.We describe a novel principle based on the monitoring of magnetic markers whichmeets these demands. Our method employs a special permanent magnet which isrepeatedly aligned by a vertically oriented pulsed magnetic field. Due to thisalignment, the marker position can be derived from the stray field componentsmeasured by commercial field sensors. Our method was evaluated by means of a 3Dintestinal phantom.The monitoring procedure yielded the time course of the marker position as a 3Dplot either in real-time or as a time-lapse movie. The spatial resolution,expressed by the mean square deviation, was better than 10 mm and is thussufficiently high to distinguish between adjacent loops of the gut. The temporalresolution, i.e. the minimum time between two successive measurements, wasabout 1 s.The presented method has very moderate technical demands and allows us tomonitor magnetic markers in real-time. The technique may be useful with respectto functional examination of the gastrointestinal tract. In pharmaceuticalresearch, our method offers the opportunity for remote drug release at anyposition of the gut.