Low end interactive image-directed neurosurgery. Update on rudimentary augmented reality used in epilepsy surgery.

Our experience with a very low end interactive image-directed (IIDS) neurosurgical system is presented. The system was developed by the author and consists of a personal desktop computer and a magnetic field digitizer. This low cost solution was pursued as an alternative to available commercial devices which were expensive and not readily modifiable for novel ideas and new applications targeted for Epilepsy surgery. The rationale and description of the system was presented last year at Medicine Meets Virtual Reality III. Included in that detailed report were the fundamental mathematics forming the basics of transformation between the surgical and the digital data spaces. Since then the system has been used in an additional 20 cases now totaling 40 in all. Its advantages and short comings will be described. The theoretical advantages of magnetic field technology over other localization methods is reviewed. Also, our experience with alternative low cost off-the-shelf interfacing devices and other related modifications are described. We have accumulated clinical data to suggest that craniotomy sizes have been reduced, electrode placement has been improved, and that interactive image-directed techniques offer advantages over other common intra-operative localization modalities such as ultrasound. Our conclusion is that interactive image-directed techniques improve neurosurgery and that inexpensive enabling technology is already available providing the technological substrate for low cost devices using virtual reality notions for surgery and medicine. This particular technology offers advantages to traditional surgical techniques demonstrating the attractiveness of rudimentary virtual reality medical applications.