Application accuracy of an electromagnetic field-based image-guided navigation system

We tested the application accuracy of an electromagnetic field-based image guidance system to compare it to traditional optically tracked systems.

A plastic skull phantom was fitted with fiducial markers rigidly attached via self-drilling bone screws. Volumetric CT scan was obtained to simulate the clinical condition. A metal disc marked in 1-mm increments was placed at the expected target point. Following registration and alignment of a trajectory guide, radial and depth localization errors were measured after both freehand and stabilized approaches on both the right and left sides. Statistical analyses of the localization errors were performed.

Total target localization error ranged from 0.71 to 3.51 mm with a mean +/- SEM of 2.13 +/- 0.11 mm. The radial error averaged 0.98 +/- 0.11 mm, depth error 1.74 +/- 0.13 mm. The freehand procedures produced a statistically greater radial, depth and total error than the fixed procedures.

Accuracy of image-guided localization using an electromagnetic field guidance system is similar to that reported for optically guided systems.