Combination of CT angiography and MRI in surgical planning of deep brain stimulation

For safe deep brain stimulation (DBS) planning, an accurate visualization and localization of vessels is mandatory. Contrast enhanced (ce) MRI depicts both arteries and veins. Computed tomography angiography (CTA) detects arteries with high geometric accuracy. We routinely combine both modalities for DBS planning.

A total of 222 trajectories in a consecutive series of 113 patients who underwent DBS operations were included. In all trajectories, the number of veins and arteries in a 10-mm diameter around the planned trajectory were counted in a ceMRI and a CTA. If a vessel was visible in both modalities, the distance was measured.

A total of 370 vessels were counted. Two hundred forty vessels (65%) were visible in both modalities. With 134 of the vessels, we detected a difference of the vessel's location with an average distance of 1.24 mm (SD 0.58). Eighty vessels (22%) were visible only in the ceMRI, 50 vessels (13%) only in the CTA. We had four bleedings (1.8% per lead) of which one was symptomatic (0.45%).

The majority of vessels were visible in both modalities; however, in more than half of these cases, the location was not identical. Here, the location in the CTA can be regarded as the ground truth. Moreover, both the CTA and the ceMRI depicted vessels not seen in the other imaging modality. We therefore assume that the combination of both imaging modalities for DBS planning increases the chance to detect vascular conflicts along the trajectory, thus reducing the risk of intracranial bleeding.