MR Thermometry-Based Feedback Control of Laser Interstitial Thermal Therapy at 980 nm

Background and Objectives: The goal of this study was to explore the feasibility of magnetic resonance thermal imaging (MRTI)-based feedback control of intracerebral laser interstitial thermal therapy (LITT), using a computer workstation and 980-nm diode laser interfaced to an MR scanner. Study Design/Materials and Methods: A computer-controlled laser thermal therapy system was used to produce 12 ex vivo lesions in 3 canine and porcine brains and 16 in vivo lesions in 6 canines with diffusing tip fiberoptic applicators and energies from 54 to 900 J. MRTI predictions of thermal damage were correlated with histopathologic analysis. Results: Under feedback control, no carbonization, vaporization, or applicator damage was observed. MRTI-based prediction of thermal dose was not significantly different from histological evaluation of achieved thermal necrosis. Conclusions: The computer-controlled thermal therapy system was effective at regulating heating, eliminating carbonization and vaporization, and protecting fiberoptic applicators. MRTI estimation of thermal dose accurately predicted achieved thermal necrosis.