Electrophysiological validation of STN-SNr boundary depicted by susceptibility-weighted MRI.
BACKGROUND
Direct targeting of subthalamic nucleus (STN) without secondary electrophysiological verification during deep brain stimulation (DBS) is replacing atlas-based indirect targeting techniques. Recent groups have reported increased contrast and better delineation of STN and substantia nigra (SNr) in susceptibility-weighted imaging protocols (SWI). We aim to validate the STN-SNr boundary seen in MRI- SWI by correlating with intraoperative microelectrode recordings (MER) as a part of developing a multi-contrast DBS MRI planning protocol.


METHODS
Prospective service evaluation involving electrophysiological verification by correlation of MER trajectory and STN-SNr boundary seen in SWI in seven consecutive patients undergoing DBS surgery were analyzed. The angle of inclination of the STN-SNr boundary and DBS trajectory in the coronal plane were calculated. Considering 4-mm dispersion of a coronal 3 MER array, we predicted, measured, and correlated the depths at which each electrode engaged the boundary.


RESULTS
All central microelectrodes identified the STN-SNr boundary within 1 mm of the predicted depth with 100 % accuracy. Ninety percent of the lateral MER identified the STN-SNr boundary as predicted from SWI and angle of the encounter of the MER front.


CONCLUSIONS
The study demonstrates that STN morphology can be depicted using SWI MRI and coincides reliably with the electrophysiological MER boundary. Thus, this imaging modality can be used to refine STN direct targeting protocols in DBS surgery for PD.
University of Nottingham Medical School, Nottingham, UK.
J
J
McEvoy
Department of Neurosurgery, Nottingham University Hospitals, Nottingham, UK. ismail.ughratdar@nhs.net.|University Hospitals Birmingham NHS Trust, Mindelsohn Way Edgbaston, Birmingham, B15 2TH, UK. ismail.ughratdar@nhs.net.
Ismail
I
Ughratdar
Department of Academic Radiology, University of Nottingham Medical School, Nottingham, UK.
S
S
Schwarz
Department of Neurosurgery, Nottingham University Hospitals, Nottingham, UK.|Department of Academic Radiology, University of Nottingham Medical School, Nottingham, UK.
S
S
Basu
D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008839:Microelectrodes; D008875:Middle Aged; D009929:Organ Size; D010300:Parkinson Disease / Q000601:surgery; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D013238:Stereotaxic Techniques; D013378:Substantia Nigra / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery; D020531:Subthalamic Nucleus / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery
Deep brain stimulation; Magnetic resonance imaging; Microelectrode recording; Parkinson’s disease; Stereotactic surgery; Substantia nigra; Subthalamic nucleus; Susceptibility-weighted imaging; Targeting