MR-compatible endoscopy and tracking for image-guided surgery

Abstract To increase patient safety of keyhole surgery, flexible endoscopy was augmented using magnetic resonance imaging (MRI). For this purpose MR-compatible 9-Fr. flexible endoscopes were developed and tested. Instrument visualisation was achieved using miniature MR tracking coils mounted either on top of the endoscope's tip or inside the working channel. The tracking data were used to superimpose a marker on an MR roadmap and to automatically and continuously image at the endoscope's current location. The techniques were tested on both 0.5-T open and 1.5-T small bore scanners using a tube phantom, a melon model and a porcine model. The combined information from MR imaging, MR tracking and endoscopic imaging were displayed on a Unix workstation using a DICOM-based user interface. The MR techniques were found to be a good complement for the limited field of view (FoV) of endoscopy. In particular, the guided scan mode allowed for direct association between the two modalities' images.