Introduction: Vascular imaging is essential to safe planning of stereotactic trajectories. This is particularly true for Stereo EEG trajectory planning, in which non-uniform trajectories are utilized to interrogate deep structures or optimize recordings for a particular hypothesis test. Rotational angiography with three-dimensional CT reconstruction enables visualization of small vessels for optimization of trajectory planning
Methods: A total of 25 patients underwent selective angiography prior to Stereo EEG planning. Syngo DynaCT™ (Siemens, Munich, Germany) was used to create angiographic CT (ACT). Arterial contrast bolus of 22mL was delivered with automated power injector at 1mL/sec over 22sec with 0.2sec delay, and imaging acquired over 20 second acquisition through 220° of rotation. Trajectory planning was performed with merged T1-weighted, gadolinium enhanced (T1-Gd) MRI and ACT on WayPoint Navigator™ planning software (FHC Inc., Bowdoin, ME).
Results: Small caliber vessels in both superficial and deep locations were routinely identified on ACT but not on T1-Gd MRI, resulting in alteration of planned trajectory. Skull thickness identified on ACT also altered trajectory entry points, particularly in thinned areas of squamous temporal bone and adjacent to prior craniotomies.
Conclusions: Three-dimensional angiographic CT (ACT) improves resolution of small caliber vessels due to image acquisition throughout the late arterial to early venous phase. This is particularly important during planning of complex Stereo EEG trajectories.
Patient Care: The primary complication of stereotactic implantation of depth electrodes is intracerebral hemorrhage, due to penetration of cortical surface or deep cerebral vessels. Imaging techniques allowing improved vessel avoidance are key to improving complication rates.
Learning Objectives: By the end of this session, participants should be able to 1) explain the angiographic technique required for acquisition of angiographic CT and 2) understand the differences in vessel resolution between traditional imaging modalities and ACT.