Device and method for 3d real-time medical instrument tracking

A method for tracking a medical instrument with a magnetic resonance tomography unit comprising a control unit, the method comprising:

• defining, by the control unit, a tracking volume enclosing a predefined trajectory;
• acquiring a first two-dimensional (2D) projection image of the tracking volume in a presence of the medical instrument with the magnetic resonance tomography unit;
• acquiring a second 2D projection image of the tracking volume in presence of the medical instrument with the magnetic resonance tomography unit, wherein a first projection vector of the first 2D projection image and a second projection vector of the second 2D projection enclose an angle larger than 20 degrees;
• determining, by the control unit, a first reference 2D image;
• determining, by the control unit, a second reference 2D image;
• suppressing, by the control unit, a background from the first 2D projection image as a function of the first reference 2D image to provide a background suppressed first 2D image;
• determining, by the control unit, a first set of coordinates of the medical instrument from the background suppressed first 2D image;
• suppressing, by the control unit, a background from the second 2D projection image as a function of the second reference 2D image to provide a background suppressed second 2D image;
• determining, by the control unit, a second set of coordinates of the medical instrument from the background suppressed second 2D image;
• and
• determining, by the control unit, a three-dimensional (3D) position of the medical instrument from the first set of coordinates and the second set of coordinates.

A computer program product comprising a computer program configured to be directly loaded into a control unit of a magnetic resonance tomography unit, wherein the computer program, when executed by the control unit, is configured to cause the control unit to:

• define a tracking volume enclosing a predefined trajectory;
• acquire a first two-dimensional (2D) projection image of the tracking volume in a presence of a medical instrument;
• acquire a second 2D projection image of the tracking volume in the presence of the medical instrument, wherein a first projection vector of the first 2D projection image and a second projection vector of the second 2D projection enclose an angle larger than 20 degrees;
• determine a first reference 2D image;
• determine a second reference 2D image;
• suppress a background from the first 2D projection image as a function of the first reference 2D image to provide a background suppressed first 2D image;
• determine a first set of coordinates of the medical instrument from the background suppressed first 2D image;
• suppress a background from the second 2D projection image as a function of the second reference 2D image to provide a background suppressed second 2D image;
• determine a second set of coordinates of the medical instrument from the background suppressed second 2D image;
• and
• determine a three-dimensional (3D) position of the medical instrument from the first set of coordinates and the second set of coordinates.