Introduction: Recently, susceptibility weighted imaging (SWI) has been used along with traditional T1-weighted gadolinium-enhanced (T1-Gd) MRI for trajectory planning during deep brain stimulation (DBS) and stereoelectroencephalograpy (SEEG) procedures. This study was performed to determine the effect of SWI versus T1-Gd vessel resolution on hemorrhagic complications during electrode implantation.
Methods: Fourteen patients undergoing DBS or SEEG electrode placement were implanted with a total of 114 electrodes. All patients underwent
3D CT and MR imaging post-operatively, and all trajectories were planned without use of SWI sequences. Post-operative CT images were co-registered to pre-operatively acquired T1-Gd and SWI sequences. Images were analyzed for presence of electrodes intersecting or passing within 1mm of cerebral vessels on both T1-Gd and SWI sequences.
Results: No patients had procedure-related intracerebral hemorrhage on post-operative MRI. Sixty unique instances of electrodes intercepting cerebral blood vessels were identified on SWI sequences (rate per electrode 52.6%, and average 4.3 interceptions per patient), of which 34 were superficial and 26 were deep in location. Eighteen interceptions were identified on T1-Gd (rate per electrode 15.8%, and average 1.3 interceptions per patient). There was a statistically significant difference in mean diameter of vessel intercepted, measuring 1.50±0.5mm on SWI, and 2.12±0.7mm on T1-Gd images (p=0.00024). Addition of electrodes passing within 1mm of cerebral vessels resulted in total 104 total instances (“interception plus near-miss”) on SWI (91.2% per electrode, 7.4 per patient) and 23 instances on T1-Gd (20.2% per electrode, 1.6 per patient).
Conclusions: Susceptibility weighted imaging is likely over-sensitive for electrode trajectory planning. There were no hemorrhages despite the high rate of electrode interception of or close proximity to cerebral vessels on SWI compared to T1-Gd imaging.
Patient Care: Our research helps neurosurgeons choose the most clinically appropriate imaging study when planning DBS and SEEG procedures in patients with epilepsy and other disorders.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Understand the importance of differentiating between imaging modalities in intracranial electrode implantation. 2) Discuss the advantages and disadvantages of SWI and T1-Gad in planning DBS and SEEG procedures. 3) Recognize the over-sensitivity of SWI in trajectory planning for electrode implantation.