Local interstitial hyperthermia in malignant brain tumors using a low-power Nd:YAG laser

摘要

Stereotactic laser-induced interstitial hyperthermia using a low-power Nd:YAG laser was performed in an experimental study on normal rat brain and on F-98 glial transplantation tumors. A new fiberoptic delivery system, the interstitial thermotherapy (ITT) laser fiber, was connected to a 1.06 $mu@m Nd:YAG laser and introduced stereotactically into the basal ganglia of the rat. Histological results of rat brains removed immediately after laser irradiation revealed a sharply demarcated lesion with a small peripheral edema. One week later, a typical necrosis became evident, while the edematous zone subsided by peripheral spread in the white matter. Four weeks following laser application, there was only a circumscribed cystic lesion without any effect in the periphery. Histological findings in the tumor model was similar. In first clinical trials, laser-induced hyperthermia was performed in patients with cerebral gliomas. Results were controlled by MR imaging and PET scan showing irreversible necrotic effects in the center of the tumor and reversible edematous changes in the periphery of the tumor. With the equipment used it is possible to map the spatial distribution of laser-tissue effects by real-time MR imaging.