Device and method for 3D real-time medical instrument tracking
Inventors
Kowalik, Grzegorz • Neji, Radhouene • RAZAVI, Reza • PUSHPARAJAH, Kuberan • ROUJOL, Sebastien
Assignees
Siemens Healthineers AG • Kings College London
Publication Number
US-12349986-B2
Publication Date
2025-07-08
Expiration Date
2044-01-02
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
A method and a magnetic resonance tomography unit for tracking a medical instrument are disclosed. In the method, a tracking volume is defined enclosing a predefined trajectory of the medical instrument. Two-dimensional (2D) projection images of the tracking volume in presence of the medical instrument are acquired with the magnetic resonance tomography unit from two different view angles. Reference 2D images for the two view angles are determined and a background of the 2D projection images is suppressed. Two sets of 2D coordinates of the medical instrument are extracted from the two 2D projection images and combined to a 3D coordinate set and output on a display.
Core Innovation
The invention pertains to a method and magnetic resonance tomography (MRT) unit for real-time tracking of a medical instrument by defining a tracking volume enclosing a predefined trajectory of the instrument. It acquires two-dimensional (2D) projection images of this volume from at least two different view angles, determines reference 2D images without the instrument, suppresses the background from the 2D projection images, and extracts 2D coordinates of the instrument. These coordinate sets from different projections are then combined to determine and output a three-dimensional (3D) position of the medical instrument.
The method addresses the challenge that medical instruments, typically made from metal or plastics, do not produce magneto-resonance active signals suitable for direct imaging in MRT, making imaging and especially real-time 3D tracking difficult. Full 3D image acquisition requires time to achieve adequate image quality, which conflicts with the need for fast integration times in real-time tracking. Existing imaging of such instruments relies on indirect effects like signal absence or artefacts, complicating detection.
The invention overcomes these challenges by acquiring projection images as 2D maps from different perspectives, using background suppression based on reference images to isolate the instrument's signal, and through coordinate transformation of the projections enabling the calculation of the instrument’s 3D position with a frame rate sufficient for operator navigation. This approach enables fast updating and depiction of the instrument’s position, improves detection reliability, and can include acquisition of 2D slices showing the instrument within its anatomical environment.
Claims Coverage
The claims include two independent claims: one for a magnetic resonance tomography unit and one for a method of tracking, each embodying core inventive features related to imaging, background suppression, coordinate extraction, and 3D position determination of a medical instrument.
tracking volume definition enclosing a predefined trajectory
The controller defines a tracking volume that encloses a predefined trajectory for the medical instrument.
acquisition of two 2D projection images from different view angles
The magnetic resonance tomography unit acquires first and second 2D projection images of the tracking volume in presence of the medical instrument, where the projection vectors enclose an angle larger than 20 degrees.
determination and use of reference 2D images for background suppression
The controller determines first and second reference 2D images to suppress background from the corresponding 2D projection images.
extraction of 2D coordinate sets and determination of 3D position
The controller determines first and second sets of coordinates of the medical instrument from the background-suppressed 2D images and combines them to determine the 3D position.
outputting the 3D position to a user
The controller outputs the 3D position of the medical instrument to a user, potentially via display in 3D-rendered images or numerical coordinates.
generation of reference 2D images from multiple projections or in absence of instrument
Reference images are determined from multiple projection images or separate acquisitions without the instrument present.
acquisition methods using 2D encoding or slice stacks with 1D projections
Acquisition of 2D projection images is done either by 2D encoding or by dividing the volume into slices and acquiring 1D projections combined into 2D images.
acquiring 2D slice images including the medical instrument
The controller acquires a 2D MR image of a slice including the medical instrument, with slice position determined by extracted coordinates.
using multiple reference images for different patient positions
A plurality of reference images representing different patient positions (e.g., respiratory or heartbeat phases) is used, selecting the most similar for background removal.
use of fat suppressing sequences for image acquisition
Fat suppressing sequences are used to improve visibility of the medical instrument in the projection images.
using peak detection algorithms for coordinate determination
Peak detection algorithms are implemented to determine the coordinates of the medical instrument from background-suppressed images.
tracking of different medical instruments including catheters
The method applies to various medical instruments, such as catheters, regardless of signal type (signal extinction or contrast enhancement).
The claims protect a comprehensive system and method for real-time 3D tracking of medical instruments within an MRT unit by combining multi-angle 2D projection imaging, background suppression using reference images, precise coordinate extraction, and 3D position determination, including features for improving image acquisition and detection robustness.
Stated Advantages
Allows quick and reliable detection and 3D tracking of the medical instrument in real time suitable for operator navigation.
Enables continuous update of background signal without separate acquisition, saving time.
Facilitates visualization of the instrument within its anatomical environment by acquiring 2D slices including the instrument.
Supports tracking over different patient positions to accommodate movement due to breathing or heartbeat.
Improves detection through peak detection algorithms that speed up and enhance reliability.
Fat suppression sequences reduce fat signals in projection images, enhancing visibility of the instrument.
Method is independent of signal type generated by the instrument, allowing use with various instrument materials.
Documented Applications
Real-time tracking and navigation of medical instruments such as catheters inside a patient's body during magnetic resonance tomography.
Use in interventional procedures requiring guidance of instruments along predefined trajectories within a patient.
Integration with treatment planning systems by importing trajectories for navigation.
Displaying 3D or 2D rendered images including instrument position for operator guidance.
Interested in licensing this patent?