Evaluation of new radiolucent polymer headholder pins for use in intraoperative computed tomography

With the introduction of intraoperative CT (iCT) scanning, neurosurgeons can now obtain images of the brain during surgery, offering the possibility of intraoperative resection control and monitoring of potential intraoperative complications. The combination of iCT with neuronavigation makes it possible to update the reference scans intraoperatively when necessary. However, the headholder pins normally used for iCT scanning still show artifacts. In the present study, new polymer pins, producing nearly no artifacts in laboratory tests, are compared with the usual pins with regard to their mechanical and artifact behavior to evaluate their potential use in the clinical routine.

Pins made of different materials (titanium, Macor, silicon nitride, zirconium oxide, sapphire, polyetheretherketone, and polyparaphenylene copolymer) were used for the fixation of 10 cadaveric heads. Special force sensors measured the fixation pressure of the pins, and histological analysis revealed the penetration depth. Computed tomography scans of a head phantom, fixed with the different pins, were obtained to reveal artifact behavior.

All pins were biocompatible. Pins did not differ significantly in fixation pressures and mechanical behavior. Penetration depths were comparable (maximum 1.4 mm) and did not cause opening of the diploe. Polymer pins made of polyparaphenylene showed the best results in artifact behavior in CT scans.

The authors' results demonstrate that the new polymer pins are comparable in their mechanical behavior to the usual pins but superior in artifact behavior. Therefore, their use in the clinical routine of iCT scanning will be beneficial for the surgeon.