Requirements for Referencing of the MKM Neuronavigation System

Summary

The localization method of the MKM neuronavigation system is based on a laser-controlled distance measurement through the microscope optic, which is mounted to a six-axis robotic arm. Due to its optical guidance, it differs from other neuronavigation systems and provides the possibility of continuous navigation during microscopic neurosurgery. The accuracy of the system was studied under experimental conditions.

Two marker systems (titanium bone screws patent no. 1129 F1, 18 mm with exchangeable marker tip, F. L. Fischer, Germany, and 1 × 4 mm microscrews, Leibinger) were used in a fixated cadaver head. The best marker selection/positioning and a CT-protocol to achieve a high 3-D resolution with minimal radiation exposure were evaluated. The accuracy of the MKM system was studied in relation to different geometrical fiducial arrangements.

To achieve CT data with a high resolution and with minimal radiation exposure a CT procedure with 1-mm slices and exclusive scanning of planes of interest was developed. The robotic arm and the optical system of the microscope allow high precision measurements with a deviation below 1–2 mm. The reference points should be spherically arranged around the target volume; linear marker arrangements must be avoided. The studied fiducials provide high precision navigation.