Interstitial laser irradiation of cerebral gliomas

Abstract

The most common type of the primary brain tumor is the glioma. For patients unsuited for open surgery, local tumor ablation may be employed as an alternative palliative option. For laser irradiation, we used a specially designed light guide (LITT Standard Applicator, Trumpf Medizintechnik, Umkirch, Germany). The light guide possesses an optical diffusion, tip which is characterized by a homogeneous spherical or ellipsoid emission profile. The light guide was introduced into an appropriate protecting sheath (Somatex, Rietzneuendorf/b Berlin, Germany). As laser light source, we used a continuous wave Nd:YAG Laser (λ=1064nm; cw; 4060n; Dornier Medizintechnik, Germering, Germany). Laser irradiation was performed under general anaesthesia in a 0.5 T open configuration MR system (Signa SP, GE, Milwaukee, Wisconsin, USA). Heretofore, the tip of the light guide was positioned in the center of the tumor using the built-in localization system (Flashpoint 3000, IGT, Boulder, CO, USA) in combination with a specially designed navigation system (Localite™, Bonn, Germany) if appropriate. The position of the light guide was then controlled using multiplanar reconstructions of T1-weighted sequences. For on-line control, temperature monitoring was performed using an experimental software package based on the temperature-dependent shift of the MR signal. Laser irradiation was ceased when the temperature monitoring revealed a steady-state temperature profile within the heated tissue. The first clinical long term results seem to be promising even in patients with bad clinical conditions and in patients with gliomas in unfavorable locations like in corpus callosum gliomas.