Accuracy of MRI compared with DSA for vascular mapping in SEEG trajectory planning

Stereoelectroencephalography (SEEG) plays a central role in the presurgical evaluation of drug-resistant epilepsy, and accurate planning of avascular trajectories is essential because hemorrhage represents the procedure's most relevant complication. This retrospective single-centre study assessed the spatial correspondence between gadolinium-enhanced MRI (Gd-MRI) and digital subtraction angiography (DSA) across vascular territories relevant to SEEG trajectory planning. Nine adult patients (mean age 36.3 ± 11.4 years) underwent both MRI and DSA between 2021 and 2022 after ethics approval and informed consent. Thirteen arterial and venous segments were analyzed, yielding 130 Cartesian displacement measurements after multimodal registration. Displacements ≤0.5 mm were reported as <0.5 mm for interpretability, while continuous values were retained for descriptive and inferential analyses. Of the 130 measurements, 88 (67.7%) fell within this threshold, while 42 (32.3%) exceeded it. Significant displacements were found in both insular M2 branches (0.91 ± 0.69 mm, p = 0.001; 0.63 ± 0.66 mm, p = 0.007), in the pericallosal artery (0.63 ± 0.50 mm, p = 0.002), and in the distal vein of Trolard (1.39 ± 0.78 mm, p < 0.001), which also showed the maximum misalignment (2.4 mm). A caudo-cranial trend was identified, with larger discrepancies involving the more superficial cortical vessels, whose injury during electrode placement carries the highest risk of clinically significant hemorrhage. These findings indicate that MRI and DSA are broadly concordant but may differ in regions that are critical for trajectory safety. This observation is hypothesis-generating and may be relevant to SEEG trajectory planning, given the anatomical vulnerability of the cortical entry zone.