In-vivo real-time magnetic resonance monitoring of endoscopic laser applications in the porcine gastrointestinal tract.
OBJECTIVE
Endoscopic laser therapy involves a risk of perforation, mainly because the depth of tissue destruction is not visible. Magnetic 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 endoscopic laser applications in the gastrointestinal tract.


METHODS
The procedures were carried out using an MR-compatible 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 macroscopic 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 imaging. Ten of the twelve laser lesions were visible with temperature-sensitive MR imaging, and their sizes correlated well with the diameters of the postmortem macroscopic coagulation zones (r = 0.76, P = 0.009). Two laser lesions 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 gastrointestinal 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 with fewer therapy sessions.
Külling
D
D
Dept. of Internal Medicine, University Hospital of Zurich, Switzerland. kulling@gmx.ch
Treiber
K
K
Fried
M
M
Marincek
B
B
Bauerfeind
P
P
D000818:Animals; D003199:Computer Systems; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D005240:Feasibility Studies; D007834:Lasers; D008279:Magnetic Resonance Imaging; D013552:Swine