Method and magnetic resonance apparatus to generate a series of mr images to monitor a position of an interventional device

A magnetic resonance (MR) apparatus to generate a series of MR images in order to monitor a position of an interventional device located in an examination region within an examination subject, comprising:

• an MR data acquisition unit in which an examination subject is located, said subject comprising an examination subject in which an interventional device is located;
• a control unit configured to operate said MR data acquisition unit to:
• (a) activate at least two phase-coding gradients in respective, different spatial directions with a gradient coil system of said MR data acquisition unit,
• (b) after the activated phase-coding gradients reach full strength, radiate a non-slice-selective radio-frequency (RF) excitation pulse with an RF transmission antenna of said MR data acquisition unit,
• (c) following a time t1 after the radiated RF excitation pulse, acquire echo signals, resulting from nuclear spins excited by the radiated RF excitation pulse, with an RF reception antenna, and enter raw data points, representing said echo signals, into a memory representing k-space, along a radial k-space trajectory predetermined by the strength of the phase-coding gradients, k-space in said memory comprising an imaging area, corresponding to said examination region,
• (d) repeat (a) through (c) with respectively different phase-coding gradient until a first region of k-space, dependent on t1, within said imaging area is filled with respective raw data points entered along respective radial k-space trajectories, and
• (e) make data entries into a remainder of said imaging area in k-space, not covered by said first region, and comprising at least a center of k-space, differently than in (a) through (d);
• a computer configured to implement a Fourier transformation of said raw data points in said first region and in said remainder of k-space to generate image data representing said examination region;
• said control unit being configured to repeat said operation of said MR data acquisition unit and said reconstruction of image data to generate multiple MR images of said examination region;
• and
• a display monitor in communication with said computer at which said computer is configured to cause said multiple MR images of said examination region to be displayed in order to allow visual determination therein of a current position of said interventional device.

A non-transitory, computer-readable data storage medium encoded with programming instructions that, when said data storage medium is loaded into a computerized control and evaluation system of a magnetic resonance (MR) apparatus, which comprises an MR data acquisition unit, to cause said computerized control and evaluation system to:

• operate said MR data acquisition unit to acquire MR data from an examination region of an examination subject in which an interventional device is located, by:
• (a) activating at least two phase-coding gradients in respective, different spatial directions with a gradient coil system of said MR data acquisition unit,
• (b) after the activated phase-coding gradients reach full strength, radiating a non-slice-selective radio-frequency (RF) excitation pulse with an RF transmission antenna of said MR data acquisition unit,
• (c) following a time t1 after the radiated RF excitation pulse, acquiring echo signals, resulting from nuclear spins excited by the radiated RF excitation pulse, with an RF reception antenna, and entering raw data points, representing said echo signals, into a memory representing k-space, along a radial k-space trajectory predetermined by the strength of the phase-coding gradients, k-space in said memory comprising an imaging area, corresponding to said examination region,
• (d) repeating (a) through (c) with respectively different phase-coding gradient until a first region of k-space, dependent on t1, within said imaging area is filled with respective raw data points entered along respective radial k-space trajectories, and
• (e) making data entries into a remainder of said imaging area in k-space, not covered by said first region, and comprising at least a center of k-space, differently than in (a) through (d);
• implement a Fourier transformation of said raw data points in said first region and in said remainder of k-space to generate image data representing said examination region;
• repeat said operation of said MR data acquisition unit and said reconstruction of image data to generate multiple MR images of said examination region;
• and
• display said multiple MR images of said examination region at a monitor to allow visual determination of a current position of said interventional device.