Endoscopic pituitary surgery with and without image guidance: an experimental comparison.
BACKGROUND
The combination of image guidance and endoscopy is the newest trend in pituitary surgery. To assess the impact of image guidance on EPS, we measured and calculated the accuracy of the system and compared some critical surgical steps with and without image guidance under experimental conditions in terms of surgical time and precision.


METHODS
Twenty cadaver heads were explored by standard endoscopic transsphenoidal surgical technique. Optic-radiologic correlations of topographic landmarks were photographed, and the system accuracy and actual visual accuracy were recorded. Some important anatomical parameters were measured in surgical field and on navigation system, and the differences were calculated and analyzed. Some critical surgical steps were recorded and compared between with and without image guidance.


RESULTS
The system accuracy (root mean square), calculated by the computer automatically, showed a mean value of 0.28 +/- 0.06 mm. In some cases, there was a small discrepancy between the visible position of the pointer and its counterpart on the navigation system; we coined this actual visual accuracy. The average value was 1.53 +/- 0.49 mm. The maximum difference between the measurements from the navigation system and from their actual visual counterparts was less than 7%. With and without image guidance, in normal anatomical conditioning, there was no statistically significant difference between the duration of ostium sphenoidale exposure and sellar window creation; however, in anatomical variations, the surgical time was shown to be significantly shorter when navigation was used.


CONCLUSIONS
We have demonstrated in this experimental setting that the electromagnetic tracking image guidance possesses a high accuracy at millimetric level and therefore provides precise localization and orientation in EPS. With the assistance of neuronavigation system, it is advantageous not only in saving operating time, but also, more importantly, in enhancing the orientation, thus, rendering surgeries safer and more efficient. During the in vivo pituitary surgery, EPS with image guidance can provide accurate and reliable stereoinformation to achieve better results with lesser risks, particularly in complex cases or in reoperations, even in the hands of experienced surgeons.
Gong
Jian
J
Division of Neurosurgery, Laboratory of Experimental Neurosurgery, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada. jg9uv@virginia.edu <jg9uv@virginia.edu>
Mohr
Gérard
G
Vézina
Jean L
JL
D002102:Cadaver; D055590:Electromagnetic Phenomena / Q000379:methods; D004724:Endoscopy / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D019635:Neurosurgical Procedures / Q000295:instrumentation*; D010902:Pituitary Gland / Q000000981:diagnostic imaging / Q000601:surgery*; D012658:Sella Turcica / Q000033:anatomy & histology / Q000601:surgery; D013101:Sphenoid Sinus / Q000033:anatomy & histology / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000592:standards; D014057:Tomography, X-Ray Computed