In-vivo real-time magnetic resonance monitoring of endoscopic laser applications in the porcine gastrointestinal tract

Background and Study Aims: Endoscopic laser therapy involves a risk of perf oration, mainly because the depth of tissue destruction is not visible. Mag netic resonance (MR) imaging is capable of showing temperature changes, and is therefore suitable for monitoring thermal therapies such as laser. This animal study assessed the feasibility of real-time MR monitoring of endosc opic laser applications in the gastrointestinal tract. Materials and Methods: The procedures were carried out using an MR-compatib le endoscope in three live pigs in a 0.5-Tesla interventional MR system. Nd :YAG laser applications were performed in the lower gastrointestinal tract (n = 7) and upper gastrointestinal tract (n = 5), and were monitored using real-time color-coded T1-weighted gradient echo sequences. The postmortem m acroscopic tissue coagulation sizes were compared with the lesion diameters seen on real-time MR. Results: The endoscope did not cause any artifacts during continuous MR ima ging. Ten of the twelve laser lesions were visible with temperature-sensiti ve MR imaging, and their sizes correlated well with the diameters of the po stmortem macroscopic coagulation zones (r = 0.76, P = 0.009). Two laser les ions were not visible on MR due to technical limitations inherent with the healthy animal model. Conclusions: The formation of endoscopic laser lesions in the porcine gastr ointestinal tract can be accurately visualized using real-time temperature- sensitive MR imaging. This new technique has the potential to spare healthy tissue while ensuring full treatment coverage of the targeted lesion,vith fewer therapy sessions.