Tracking system and pulse sequences to monitor the position of a device using magnetic resonance

A method for tracking a location of an invasive device in real-time within a subject employing magnetic resonance (MR) comprising the steps of:

• a) applying a homogeneous magnetic field having substantially uniform amplitude over said subject;
• b) transmitting radiofrequency (rf) energy of a selected duration, amplitude and frequency into said subject to cause nutation of a selected ensemble of spins within said subject;
• c) varying amplitude of the magnetic field in at least one spatial dimension over said subject over time causing the selected ensemble of spins to emit an MR response signal;
• d) detecting the MR response signal from the selected ensemble of spins within the subject through a coil attached to said invasive device;
• e) processing the detected MR response signal;
• f) calculating a location of said invasive device in real-time from the processed MR response signal;
• and
• g) displaying the location of said invasive device to an operator.

A real-time magnetic resonance (MR) tracking system comprising:

• a) an invasive device adapted to be inserted into a subject;
• b) static magnetic field means adapted for applying a homogeneous magnetic field having substantially uniform amplitude over the subject;
• c) radiofrequency (rf) transmitter means attached to the invasive device adapted for transmitting rf energy of a selected duration, amplitude and frequency into the subject to cause nutation of a selected ensemble of spins in the subject;
• d) gradient means adapted for varying the amplitude of the magnetic field in at least one spatial dimension over the subject over time causing the selected ensemble of spins to emit an MR response signal;
• e) detection means adapted for detecting the MR response signal from the selected ensemble of spins within said subject;
• f) calculation means responsive to the detection means adapted for calculating a location of the invasive device from the detected MR response signal;
• g) controller means coupled to the rf transmitter means, the detection means, the calculation means and the gradient means adapted for activating the rf transmitter means, the detection means, the calculation means and the gradient means according to a desired MR tracking sequence repeatedly for the purpose of tracking the invasive device in real-time;
• and
• h) display means responsive to the calculation means for displaying the location of said device to an operator.

A method for tracking a location of an invasive device in real-time within a subject employing magnetic resonance (MR) comprising the steps of:

• a) applying a homogeneous magnetic field having substantially uniform amplitude over said subject;
• b) transmitting radiofrequency (rf) energy of a selected duration, amplitude and frequency from a coil attached to said invasive device into said subject to cause nutation of a selected ensemble of spins within said subject;
• c) varying amplitude of the magnetic field in at least one spatial dimension over said subject over time;
• d) detecting an MR response signal with an external coil surrounding said subject from the selected ensemble of spins within said subject;
• e) processing the detected MR response signal;
• f) calculating a location of said invasive device from the processed MR response signal;
• and
• g) displaying the location of said invasive device to an operator.