Thermography of an ablation site is carried out by navigating a probe into contact with target tissue in the heart, obtaining a first position of a position sensor in the probe and acquiring a first magnetic resonance thermometry image of the target tissue. The method is further carried out during ablation by iteratively reading the position sensor to obtain second positions, and acquiring a new magnetic resonance thermometry image of the target tissue when the distance between the first position and one of the second positions is less than a predetermined distance. The images are analyzed to determine the temperature of the target tissue.

A method and apparatus for invasive medical procedures uses a tool that includes an operative portion and a stem having a distal end attached to a proximal end of the operative portion and a proximal end configured to be held outside a subject during the invasive medical action. The tool can include a recess along the stem and a viewport. The recess is configured to removably engage an electromagnetic tracking system component comprising an electromagnetic sensor and an insulated electrical wire connected to the electromagnetic sensor. The viewport is configured to reveal a portion of the recess where the electromagnetic sensor is to be disposed. Alternatively, a frame is rigidly and removably attached to a proximal portion of the tool. The frame is also rigidly attached to electromagnetic tracking sensor suite that provides position and orientation of the frame with six degrees of freedom.

For the field of determining the position of an invasive device (1) a solution for improving the localization of the invasive device (1) is specified. This is achieved by an arrangement and a method for determining the position of an invasive device (1), wherein an optical shape sensing system for sensing a position and/or shape of the invasive device (1) is provided, wherein the system is arranged to localize at least one point P.sub.i on the invasive device (1) at a position x.sub.i, y.sub.i, z.sub.i, with some en-or margin (2Δx.sub.i, 2Δy.sub.i, 2Δz.sub.i) in a region of interest (3), localizing and reconstructing at least one point P.sub.i on the invasive device (1) at a position x.sub.i, y.sub.i, z.sub.i, with some error margin (2Δx.sub.i, 2Δy.sub.i, 2Δz.sub.i) in a region of interest (3) by the optical shape sensing system. An MRI system is also provided for measuring the position x.sub.i, y.sub.i, z.sub.i of the point P.sub.i on the invasive device (1) within the error margin in the region of interest at least in one spatial direction by the MRI system, wherein a signal of the magnetization in the error margin (2Δx.sub.i, 2Δy.sub.i, 2Δz.sub.i) is read out by the MRI system and a position of the invasive device (1) is determined based on the signal. The position x.sub.i, y.sub.i, z.sub.i, of the point P.sub.i on the invasive device (1) in the region of interest (3) determined by the optical shape sensing system is corrected with the x.sub.i, y.sub.i, z.sub.i, of the point P.sub.i on the invasive device (1) in the region of interest (3) determined by the MRI system by a calculating system to an actual position of the point P.sub.i on the invasive device (1).

Devices for transferring fluid to or from a subject include an extension tube assembly with an axially extending inner tube configured to couple to an elongate tubular cannula having opposing proximal and distal ends with an axially extending lumen and an axially extending inner tube. The inner tube extending through the tubular cannula defines an exposed needle tip and is in fluid communication with the inner tube of the extension tube assembly. The needle tip extends out of a distal end of the tubular cannula a suitable distance.

An electrode for use on a medical device is disclosed. The electrode may have a main body of electrically conductive material extending along an axis and may have a proximal end and a distal end. The electrode may also include a magnetic resonance imaging (MRI) tracking coil disposed in the body. The MRI tracking coil may comprise electrically insulated wire. A catheter including an electrode, as well as a method for determining the location of an electrode, are also disclosed.

An embodiment in accordance with the present invention provides an improved electrically conductive transmission line that is radio frequency (RF) safe. The present invention does not include any inductive coupling elements. Instead, multiple coils constructed from twisted pairs of wires are used to block the common mode of the received magnetic resonance (MR) signal that can cause heating, while passing the differential mode that is used for tracking and/or imaging. These twisted pair coils are easily manufactured out of a single length of twisted pair wire, but multiple segments could also be used. The twisted pair coils of the present invention are easier to manufacture than the pre-existing inductive coupling element-based transmission lines, and occupy less overall volume inside a medical device. The individual coils of twisted pairs are tuned to the resonant frequency of the MR scanner by the addition of appropriate capacitors.

The present invention relates to a catheter (2) for applying energy to an object (6) and a magnetic resonance imaging system (1) for localizing the catheter (2). The catheter (2) comprises an energy application element for applying energy to the object (6), and a cavity for providing a magnetic resonance fluid from which magnetic resonance signals generated by the magnetic resonance imaging system (1) are receivable, wherein the cavity is adapted for providing a cooling fluid as the magnetic resonance fluid for cooling the energy application element. The catheter (2) comprises further a tracking coil (15) for tracking the catheter (2), wherein the tracking coil (15) is adapted to receive the magnetic resonance signals from the magnetic resonance fluid. Thus, the magnetic resonance fluid fulfils at least two functions, providing magnetic resonance signals for tracking the catheter (2) and cooling the energy application element.

A method for magnetic resonance imaging uses an electromagnet [304], which may have open geometry, to generate a spatially nonuniform magnetic field within an imaging region [306]. The current through the electromagnet is controlled to repeatedly cycle the nonuniform magnetic field between a high strength for polarizing spins and a low strength for spatial encoding and readout. Using RF coils [308], excitation pulses are generated at a frequency that selects a non-planar isofield slice for imaging. The RF coils are also used to generate refocusing pulses for imaging and to generate spatial encoding pulses, which may be nonlinear. Magnetic resonance signals originating from the selected non-planar isofield slice of the nonuniform magnetic field in the imaging region [306] are detected using the RF coils [308] in parallel receive mode. MRI images are reconstructed from the parallel received magnetic resonance signals, e.g., using algebraic reconstruction.

The disclosed apparatus, systems and methods relate to interventional magnetic resonance imaging (iMRI). More specifically, clinical applications of the disclosed include magnetic resonance (MR) guided procedures such as endovascular interventions, percutaneous biopsies or deep brain stimulation.

Improved magnetic resonance imaging systems, methods and software are described including a low field strength main magnet, a gradient coil assembly, an RF coil system, and a control system configured for the acquisition and processing of magnetic resonance imaging data from a patient while utilizing a sparse sampling imaging technique.