MRI GUIDED INTERSTITIAL LASER THERAPY IN A RAT MALIGNANT GLIOMA MODEL

We have used MR monitoring to guide and evaluate the effects of the Nd :YAG interstitial laser on a well-characterized rat brain tumor model (C6). MRI was used to determine the tumor size, verify the location of the interstitial probe, and evaluate the size and location of the las er-induced lesion during and after treatment. During laser irradiation , an irreversible loss of signal intensity at the fiber tip and a reve rsible decrease in signal intensity around it were observed with MRI. None of the treatment protocols affected mean rat survival significant ly. Although MRI-guided interstitial laser therapy appears to be safe and easy, it does not provide a curative treatment for spatially disse minated gliomas where a ''target volume'' cannot be adequately defined . Better results can be expected, especially in well-defined tumors, w ith improvements of both the imaging techniques and the laser treatmen t protocol. (C) 1993 Wiley-Liss, Inc.