Abstract: Device and method for treating vascular defects by filling the defect with magnetically controlled devices. Vascular defects include aneurysms and arteriovenous malformations (AVMs), particularly in the head and neck of the patient. The magnetic devices fall into categories of ferro-fluids, magnetic objects and magnetic coils. Ferro-fluids consist of a magnetic particulate that is combined with a glue or polymer agent. The ferro-fluid is magnetically held and solidified, while the adhesive agent cures. Magnetic objects such as polyvinyl alcohol (PVA) coated magnetic particles can be injected into a vascular defect such as an AVM. The magnetic objects are attracted into pre-selected AVM branches by the application of a magnetic gradient. Magnetic coils are magnetically steered and held within an aneurysm to improve coil delivery. Large neck aneurysms are particularly assisted by this method, due to the need to steer the coil towards the center of the aneurysm and to hold the coils within the aneurysm.

Abstract: A device and a method for guiding or applying force to a magnetic implant within the body of a patient. The device includes a bed for support of the patient, a set of separately energizable electromagnets or separately controllable permanent magnets so arranged to produce magnetic fields of varying orientations in a treatment region of the patient, and a processor that controls the currents in the electromagnets, or shutters on the permanent magnets to produce a selected magnetic field and/or gradient for guiding or moving the implant. The magnets are configured to allow a medical imaging device to be used to provide a real-time display of an operating procedure in which magnetic guidance is used.

Abstract: Methods and apparatuses for displaying and using a shaped field of a repositionable magnet to move, guide, and/or steer a magnetic seed or catheter in living tissue for medicinal purposes. A moveable magnet assembly and a portion of a patient's body undergoing magnetically-aided surgery are both provided with fiducial markers. The portion of the patient's body is fixed in a location in which the fiducial markers are sensed and located by a set of localizers. The positions of the fiducial markers are determined by a processor, which operates on a stored representation of the magnetic field of a magnet in the magnet assembly to provide a display of the present magnetic field of the magnet. This display may be superimposed over an MRI, X-ray or CAT image during surgery. The repositionable magnet can be an electromagnet.

Abstract: A magnetic embolic agent for magnetic placement in a vascular defect includes a bicompatible polymer, a solvent, an adhesive, and magnetic particles.

Abstract: A method of applying an elongate magnetic element to the surface of an internal body structure includes applying a magnetic field to the elongate magnetic element to orient the elongate magnetic element in a selected orientation; and applying a magnetic gradient to the elongate magnetic element to draw the elongate magnetic element against the surface of the body structure.

Abstract: A system of navigating a magnetic medical device within that part of a patient located within an operating region of the system, the system comprising magnets, and preferably electromagnets, arranged to provide a magnetic field sufficient to navigate the magnetic medical device within the operating region. There are preferably three magnetic coils arranged in mutually perpendicular planes such that their axes intersect in the operating region. The magnetic coils are sized and arranged so that a patient can easily access the operating region to allow virtually any portion of the patient to be positioned within the operating region. The openness of the magnetic system allows access to the operating region by a bi-planer imaging system.

Abstract: Methods and apparatuses for displaying and using a shaped field of a repositionable magnet to move, guide, and/or steer a magnetic seed or catheter in living tissue for medicinal purposes. A moveable magnet assembly and a portion of a patient's body undergoing magnetically-aided surgery are both provided with fiducial markers. The portion of the patient's body is fixed in a location in which the fiducial markers are sensed and located by a set of localizers. The positions of the fiducial markers are determined by a processor, which operates on a stored representation of the magnetic field of a magnet in the magnet assembly to provide a display of the present magnetic field of the magnet. This display may be superimposed over an MRI, X-ray or CAT image during surgery. The repositionable magnet can be an electromagnet. In some embodiments, a computer calculates orientations and currents for an external electromagnet to move the implanted magnetic object in the patient's body through a desired path.

Abstract: An intracranial bolt, for installation in an opening in the skull to provide access to the brain for a medical device, has a bore therethrough for the passage of the medical device, and an inflatable member in the bore which when inflated engages a medical device in the bore, releasably anchoring the device. The inflatable member comprises a cylinder of flexible sheet material inside the bore and secured to the wall of the bore defining an annular pocket therebetween. A passage extends through the bolt to the pocket for the introduction of fluid into the pocket to expanding radially inwardly. The bolt in a medical procedure on the brain by forming an opening in the skull; installing the intracranial bolt in the opening in the skull; and securing the cap on the bolt. When it is time to conduct the procedure, the cap is removed and a medical device can be inserted into the brain through the bolt. The inflatable member can be inflated to temporarily hold the medical device in place.

Abstract: A system for controlling a magnetic element within a selected region of a patient's body includes a magnet assembly comprising first and second mutually attracting, opposed magnet faces separated by a gap; and a magnet support for supporting the magnet assembly adjacent the selected region of the patient's body to apply a magnetic field within the selected region, and moving the gap of the magnet assembly relative to the selected region of the patient's body to change the magnetic field within the selected region. The method A method of controlling a magnetic element within a selected region of a patient's body, the method comprising the controlled application of a magnetic field to the magnetic element in the selected region with a pair of mutually attracting opposed magnets separated by a gap.

Abstract: A method and apparatus for ramping current in an electromagnet in which a coil is used to generate the magnetic field provides rapid changes in the generated magnetic field. The method allows a change in current in the coil to be accomplished more rapidly than by applying a step change in voltage, when superconducting coils subject to quenching are used or when nonsuperconducting coils subject to other physical limitations are used. The method requires that both the current I(t) through the coil and the first derivative of the current vary with respect to time t during the ramping period, so that magnitude of the derivative of the current is higher when the magnitude of applied current is lower, lower when the magnitude of the applied current is higher. One variation of this method supplies (or removes) a constant amount of power from the magnetic field of the magnet, while another variation compensates for both self-generated eddy current losses and self-generated high field effects.

Abstract: The movement of a catheter through a medium, which may be living tissue such as a human brain, is controlled by mechanically pushing a flexible catheter having a magnetic tip through the medium and applying a magnetic field having a magnitude and a direction that guides the mechanically-pushed catheter tip stepwise along a desired path. The magnetic field is controlled in a Magnetic Stereotaxis System by a processor using an adaptation of a PID (proportional, integral, and derivative) feedback method. The magnetic fields are applied by superconducting coils, and the currents applied through the coils are selected to minimize a current metric.

Abstract: A device and method for specifying the orientation of a magnetic field produced in a patient to aid surgical procedures involving an implanted magnet. The device includes a processor, a pointing device, a magnet assembly generating a magnetic field, a display, and a medical imaging device that provides three-dimensional imaging of an operating region of a patient during surgery. Fluoroscopic images of an operating region 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 of the magnetic delivery vehicle.

Abstract: A catheter and magnet combination adapted for intraparenchymal positioning of the catheter in the body with a magnetic field. The catheter has a proximal and distal ends and a lumen therebetween. A magnet is disposed in the distal end of the lumen so that the distal end of the catheter can be positioned within the body with the aid of an externally applied magnetic field. A tether is attached to the magnet and extends through the lumen and out the proximal end so that the magnet can be removed from the catheter through the lumen once the distal end of the catheter is properly positioned. In one embodiment of the invention, the tether is sufficiently stiff to be able to push the catheter through the tissue. With this embodiment, the magnetic field orients the magnet and thus the tip of the catheter, and some or all of the force for moving the catheter is applied via the tether.

Abstract: A control method permits the operation of multiple superconducting magnetic coils so as 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 more detailed preoperative imaging of some other kind. A computer contains the preoperative images and the fluoroscopic images, as well as the means to effect changes in the coil currents so as to accomplish the desired magnetic object motion and positioning. The control method operates the coils in pairs on opposite sides of the body in a manner 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 method should function well and provide advantages with coils which are not superconducting as well.