Stereotactic-guided laser-induced interstitial thermotherapy (SLITT) in gliomas with intraoperative morphologic monitoring in open MR

Abstract

Stereotactic guided laser-induced interstitial thermotherapy (SLITT) is a minimal invasive method to produce thermo necrosis in cerebral tumor tissue. Clinical data about dose/response relationship and patients outcome is poor. Twenty-four patients with brain tumors were treated with SLITT, totally 30 laser procedures were performed. Under local anesthesia 600 micrometers laser-fiber were inserted by the stererotactic-guided technique. IN open MR the denaturation of the tumor by a Neodym-YAG-laser was monitored using T1-weighted 3D tumor FLASH sequences. Laser energy was applied in steps of 400 to 1200 Joules. Development of necrosis at a mean total energy-dose of 2979 Joules could be monitored in all procedures. Initial signal changes were seen after a mean of 1250 Joules. Mean max total lesion size was 21.2 mm. The higher the total energy, the larger the thermo lesion, but no linear relationship could be seen. Tumor tissue response showed no dependency form tumor grading. Although lesion-size basically is energy dependent, it should be applied individually, since thermo response in brain tumors varies due to different optical properties. Energy application in steps of 500 Joules monitored in near on-line modus in an open MR-system is safe and feasible. Conclusions about the clinical value of SLITT are not definite.