Intraoperative MRI Imaging Strategies to Evaluate for Complications during DBS Surgery Olivia Huston Kendall Lee MD, PhD Robert Watson MD, PhD Matt Bernstein PhD John Huston MD Kiaran McGee PhD Mayo Clinic Rochester, MN

Intraoperative MRI During DBS Surgery Purpose To determine the optimal imaging sequences, the imaging findings and the clinical consequences of those findings for MRI performed during DBS surgery.

Intraoperative MRI During DBS Surgery Methods 143 patients underwent 152 DBS surgeries utilizing intraoperative 1.5T MRI. MRI sequences utilized: - T1 MP-RAGE pre and intra-op - T2* GRE intra-op - T2 FLAIR selectively - T2 FSE selectively FLAIR and T2 FSE used …… FLAIR – T2 weighted – shows extraaxial hyperacute blood subarachnoid and subdural FSE – Fast Spin Echo

Intraoperative MRI During DBS Surgery Results Number of Surgeries: 152 Subdural Hematomas: 5 Subarachnoid Hemorrhages: 3 Intraparenchymal Hemorrhage: 1 Subarachnoid Air: 4 Brain Shift: 144

Intraoperative MRI During DBS Surgery Subdural Hematoma Number of SDH: 5 Average thickness: 5.2 mm Range: 4-8 mm

Subdural Hematoma A GRE - isointense B MP-RAGE - iso C FLAIR – high signal intensity D CT – high attenuation Subdural Hematoma

Intraoperative MRI During DBS Surgery Subarachnoid Hemorrhage Number of SAH: 3 One patient experienced headache and disorientation requiring 2 additional days of hospitalization. Symptoms cleared prior to discharge. This is the only patient in our study that had acute clinical changes associated with intracranial air or hemorrhage

Subarachnoid Hemorrhage A – pre operative MP-RAGE B – MPRAGE – iso – CSF displaced by iso C – FRE - iso D – FLAIR – high signal in subarachnoid space E – CT – high attenuation in the subarachnoid space Subarachnoid Hemorrhage

Intraoperative MRI During DBS Surgery Intraparenchymal Hemorrhage Number Hemorrhages: 1 5 x 5 mm

Intraparenchymal Hemorrhage B C – GRE – slightly high signal compared to the adjacent brain tissue D – FSE – clear high signal E – confirmed on CT Intraparenchymal Hemorrhage

Intraoperative MRI During DBS Surgery Subarachnoid Air Number of SA Air: 4

Subarachnoid Air * Left lead replacement surgery A pre-operative – solcus is large b/c of previous surgery B postop – MP-RAGE – air is replaceing CSF but both are very low signal C – GRE – low signal – mimicks acute blood D – CT confirms air – low attenuation Subarachnoid Air

Intraoperative MRI During DBS Surgery Brain Shift Number with Shift: 144 Average: 0.6 cm Range: 0.1-1.3 cm

Brain Shift

Intraoperative MRI During DBS Surgery Conclusions Intracranial hemorrhage is occasionally identified but is rarely clinically significant. One delayed SDH required evacuation. Brain shift during DBS surgery is common. Subarachnoid air mimics subarachnoid blood on GRE. Selective use of T2 FLAIR and T2 FSE imaging can confirm the presence hemorrhage or air and precludes the need for CT exams.