Laser-induced thermotherapy of cerebral neoplasia under MR tomographic control

The purpose of this study was to monitor interstitial laser therapy (LITT) in palliative treatment of brain tumours by using temperature-sensitive MRI sequences and image-processing techniques in real-time. Three consenting patients with recurrent gliomas were treated with LITT (3-4.5 W, 3-6 min). Temperature sensitive monitoring was performed either by T₁ weighted fast spin echo (FSE) sequences, combined with pixel subtraction, optical flow (OF) computation, or by spoiled gradient recalled (SPGR) sequences used for chemical shift-based imaging. Both sequences were applied at 0.5 T (Signa SP,GE Medical System, Milwaukee, WI, USA). Pixel subtraction identified thermal changes in brain tumours, but could not evaluate the temperature values as chemical-shift based imaging. OF computation displayed the predicted course of thermal changes and revealed that the rate of heat deposition can be anisotropic, which may be related to heterogeneous tumour structure and/or vascularisation. Local tumour control was achieved with laser energy deposition giving clinically stable conditions for several months. Carefully applied LITT and thermal monitoring may evolve as an alternative palliative concept for patients with end-stage cerebral gliomas, reducing clinical symptoms from circumscribed areas of pathology.