A COMPARISON OF FLUOROSCOPY AND COMPUTED TOMOGRAPHY-DERIVED VOLUMETRIC MULTIPLE EXPOSURE TRANSMISSION HOLOGRAPHY FOR THE GUIDANCE OF LUMBARPEDICLE SCREW INSERTION

HOLOGRAPHIC TECHNOLOGY HAS recently been modified in such a manner tha t it may now provide clinical use. It allows the visualization of comp lex structures in three dimensions and permits clinician interaction w ith the image, which, in turn, provides significant additional geometr ic and anatomic information. To objectively assess the potential clini cal applicability of holography in pedicle screw placement, we studied 11 elderly human cadavers. All of the cadavers, each of which showed significant degenerative disease of the lumbar spine, underwent thin-s ection computed tomographic scans of the lumbar spine. The acquired di gital information was processed, and volumetric multiple exposure tran smission holographic images were rendered. Pedicle screws were passed into anatomically acceptable and radiographically visualized L3-L5 ped icles in each cadaver, half using fluoroscopic guidance and half using holographic guidance alone. The accuracy of screw placement was objec tively assessed by a three-point grading scale. The total score for th e placement of each pedicle screw was determined by both trajectory (l ocation within the pedicle) and accuracy (containment within the verte bral body) of screw tip placement parameters. Three points were possib le for each screw placed. Screw placement in the last six cadavers was individually timed for each technique, and fluoroscopic time was also recorded. Each technique was used on 27 pedicles. The total score for fluoroscopic screw placement was 71 (71 of a possible 81; 88%) and fo r holographic screw placement was 74 (74 of a possible 81; 91%). In th e last six cadavers, the screw placement time (per cadaver) was 8 minu tes for fluoroscopic placement and 3.6 minutes for holographic placeme nt. Fluoroscopic time averaged 1.9 minutes per cadaver. The close appr oximation of the accuracy of holographic guidance with that of fluoros copic guidance, combined with its speed and safety, indicates that vol umetric multiple exposure transmission holography may facilitate pedic le screw placement.