title: Automated multiple trajectory planning algorithm for the placement of stereo-electroencephalography (SEEG) electrodes in epilepsy treatment.
abstract: OBJECTIVE
  About one-third of individuals with focal epilepsy continue to have seizures despite optimal medical management. These patients are potentially curable with neurosurgery if the epileptogenic zone (EZ) can be identified and resected. Stereo-electroencephalography (SEEG) to record epileptic activity with intracranial depth electrodes may be required to identify the EZ. Each SEEG electrode trajectory, the path between the entry on the skull and the cerebral target, must be planned carefully to avoid trauma to blood vessels and conflicts between electrodes. In current clinical practice trajectories are determined manually, typically taking 2-3 h per patient (15 min per electrode). Manual planning (MP) aims to achieve an implantation plan with good coverage of the putative EZ, an optimal spatial resolution, and 3D distribution of electrodes. Computer-assisted planning tools can reduce planning time by quantifying trajectory suitability.
  
  
  METHODS
  We present an automated multiple trajectory planning (MTP) algorithm to compute implantation plans. MTP uses dynamic programming to determine a set of plans. From this set a depth-first search algorithm finds a suitable plan. We compared our MTP algorithm to (a) MP and (b) an automated single trajectory planning (STP) algorithm on 18 patient plans containing 165 electrodes.
  
  
  RESULTS
  MTP changed all 165 trajectories compared to MP. Changes resulted in lower risk (122), increased grey matter sampling (99), shorter length (92), and surgically preferred entry angles (113). MTP changed 42 % (69/165) trajectories compared to STP. Every plan had between 1 to 8 (median 3.5) trajectories changed to resolve electrode conflicts, resulting in surgically preferred plans.
  
  
  CONCLUSIONS
  MTP is computationally efficient, determining implantation plans containing 7-12 electrodes within 1 min, compared to 2-3 h for MP.
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK. rachel.sparks@ucl.ac.uk.
authors.forename: Rachel
authors.initials: R
authors.lastname: Sparks
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Gergely
authors.initials: G
authors.lastname: Zombori
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Roman
authors.initials: R
authors.lastname: Rodionov
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Nowell
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Sjoerd B
authors.initials: SB
authors.lastname: Vos
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Zuluaga
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Beate
authors.initials: B
authors.lastname: Diehl
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Wehner
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Miserocchi
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: McEvoy
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.|National Hospital for Neurology and Neurosurgery (NHNN), London, UK.
authors.forename: John S
authors.initials: JS
authors.lastname: Duncan
authors.affiliation: Centre for Medical Image Computing, University College London, London, UK.|Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, London, UK.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Ourselin
mesh_terms: D000465:Algorithms; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D019635:Neurosurgical Procedures / Q000379:methods*; D012189:Retrospective Studies; D012306:Risk; D012886:Skull; D013238:Stereotaxic Techniques; D025321:Surgery, Computer-Assisted / Q000379:methods*
keywords: Computer-assisted planning; Epilepsy; Image-guided neurosurgery; Neurosurgery