Abstracts

Rationale: Laser interstitial thermocoagulation therapy (LITT) is a minimally invasive surgical treatment of mesial temporal lobe epilepsy (mTLE). Early seizure freedom rates are comparable to open resection, but could be improved by increased volume of anterior, medial, and inferior amygdalohippocampal ablations. However, the dynamics of heat spread in the complex mesial temporal anatomy, and therefore control of heating, is poorly understood. We aim to characterize spatiotemporal dynamics of heat spread in mesial temporal LITT cases.

Methods: We retrospectively analyzed thermal data, patient characteristics, and seizure outcomes in mTLE patients who underwent LITT. Raw thermal data were analyzed using custom MATLAB scripts. We organized thermal data by slice position and acquisition to map the spatiotemporal dynamics of heat spread relative to laser probe. For each slice, we identified a region of interest (ROI) centered on the probe tip. Based on the time-course of temperature in a voxel and 3D distance from the laser probe, we generated a slope of temperature increase for each acquisition. After incorporating energy delivered, we calculated the specific heat capacity for each voxel in the ROI. 

Results: We were able to capture temperature-time course at a 2x2 mm resolution for the duration of laser heating. We observed that the rate of heat spread in lesional epileptic tissue fits an elliptical pattern. The slope of heat spread declines as a function of 3-dimensional distance from the laser probe. We also quantified the dynamics of heating multiple times in relation to laser position, latency of light diffusion, to compare rates of first versus multiple re-heating of tissue.

Conclusions: Preliminary analysis on a homogenous group of mTLE patients and ablations show that high-resolution temperature dynamics are feasible as a first step to capture the effect of tissue characteristics on LITT heat spread.

Funding: Not applicable