Dr. Michael W. Vannier
University of Iowa
TITLE: Image-Guided Magnetic Surgery
Monday, November 19, 2001
1245 Seamans Center
Catheters, magnetic seeds, untethered endoscopes, and slurries of ferromagnetic particles may be moved, guided, and/or steered in living tissue by the shaped field of a repositionable external magnet for minimally invasive surgical procedures. A magnetic surgery system (MSS) consists of a control processor, a pointing device, a magnet assembly generating a magnetic field, a display, and a 3D medical imaging system. Biplane fluoroscopic images of the patient in which the magnetic delivery vehicle is implanted are shown on a screen, each image representing a projection in space of the operating region. The pointing device is operated to move a cursor from a projection of a present location of the magnetic delivery vehicle to a projection of a desired future location. When the locations are completely specified, the currents applied to multiple magnets in the MSS produce a magnetic field and move or orient the magnetic delivery vehicle. Multiple superconducting magnetic coils are activated simultaneously to move a magnetic object to precisely specified locations within the body under command of a physician-operator observing the motion with live fluoroscopic imaging fused with a more detailed preoperative image. A workstation contains the preoperative images and the fluoroscopic images, as well as the means to effect changes in the coil currents and position the magnetic object motion as desired. The control method operates the coils in pairs on opposite sides of the body to minimize the necessary current changes, thus avoiding the quenching of the superconducting coils. Combinations of these pairs can execute motion of the magnetic object in any direction in an impulsive manner and with high precision. The display provides real-time imaging of the implanted magnetic object in comparison to the desired path as the object is moved. This system has applications in neurosurgery, cardiac electrophysiology mapping and ablation, brachytherapy, and endoscopy that are currently under development. The technical features of an MSS and examples of its applications will be presented.
1 Stereotaxis, Inc., St. Louis, MO, USA.