Magnetic stereotaxis: a technique to deliver stereotactic hyperthermia

Advances in imaging techniques and computer software over the past decade now define brain abnormalities such as tumors in precise, three-dimensional images. We have taken advantage of these technological improvements in designing a system capable of performing magnetic manipulation of an object in a nonlinear trajectory and able to deliver hyperthermia to highly specific targets within the brain. This device relies on external magnets to pull a small metal pellet (thermoceptor) through the brain, and on biplane fluoroscopy to localize the thermoceptor with respect to previously obtained magnetic resonance images. A radiofrequency tuned circuit serves as the hyperthermia applicator and selectively heats the thermoceptor. This paper describes experiments conducted in a series of dogs showing that all three components of the system (magnetic drive, stereotactic real time imaging, and hyperthermia) can be achieved. Integration of the system was accomplished in one animal. These encouraging results need further detailed substantiation in each of the components, yet demonstrate the feasibility of such a device.