How is the small magnet guided through the brain?
The MSS generates a magnetic field whose contours are determined by the strength of the current flowing to each of six superconducting magnets. Increasing or decreasing the current to one magnet alters the contours of the field, which alters the direction in which the small magnet moves. Does the small magnet pull the guidewire and catheter? No. A computer-controlled device, the guidewire positioning system, provides the mechanical force to advance the guidewire. So the positioning system is like the system s motor, whereas the magnet is like its steering wheel. The surgeon steers by remote control from the computer console. How does the surgeon know where the small magnet is in the brain? The MSS contains a fluoroscope, which takes X-ray images in two planes of the patient s head every second or two. Because the six metal markers show up on these images as well as on the MRIs, the two types of images can be superimposed. Therefore the computer can mark the position of the magnet which
