Multicentre validation of automated trajectories for selective laser amygdalohippocampectomy

Introduction Laser interstitial thermal therapy (LITT) is a novel minimally invasive alternative to open mesial temporal resection in drug-resistant mesial temporal lobe epilepsy (MTLE). The safety and efficacy of the procedure are dependent on the pre-planned trajectory and the extent of the ablation achieved. Ablation of the mesial hippocampal head has been suggested to be an independent predictor of seizure freedom, whilst sparing of collateral structures is thought to result in improved neuropsychological outcomes. We aim to validate an automated trajectory planning platform against manually planned trajectories to objectively standardize the process. Methods Using the EpiNav™ platform we compare automated trajectory planning parameters derived from expert opinion and machine learning to undertake a multicentre validation study against manually planned and implemented trajectories in 95 patients with MTLE. We estimate ablation volumes of regions of interest and quantify the size of the avascular corridor through the use of a risk score as a marker of safety. We also undertake blinded external expert feasibility ratings and preference rankings between the trajectories. Results Automated trajectory planning employs a complex algorithm to optimize planning parameters in order to maximize ablation of the mesial hippocampal head and amygdala, whilst sparing the parahippocampal gyrus. Automated trajectories resulted in significantly lower risk scores and greater amygdala ablation percentage, whilst overall hippocampal ablation percentage did not differ significantly. Blinded external expert raters were significantly more likely to give preference to automated compared to manually planned trajectories. Conclusion Retrospective studies of automated trajectory planning show much promise in optimizing safety parameters and ablation volumes during LITT for MTLE. Multi-center validation provides evidence that the algorithm is robust and blinded external expert ratings indicate that the trajectories are clinically feasible. Prospective validation studies are now required to determine if automated trajectories result in improved seizure freedom rates and reduced neuropsychological deficits