Apparatus and method for interactive 3D registration of ultrasound and magnetic resonance images based on a magnetic position sensor

An apparatus, comprising:

• a magnetic position sensor;
• and
• a control unit coupled to the magnetic position sensor and to a processor, the control unit being capable of cooperating with the processor to obtain a first transformation by registering a coordinate space associated with images of a first modality to a coordinate space of the magnetic position sensor, the control unit being capable of cooperating with the processor to obtain a second transformation by registering a coordinate space associated with images of a second modality to the coordinate space of the magnetic position sensor, the processor being capable of converting coordinates of images associated with one of the modalities to coordinates of images associated with the other one of the modalities based on the first and second transformations,
• wherein the magnetic position sensor comprises a transmitter and a receiver mounted on an object, the control unit being capable of cooperating with the processor to transform the coordinate space associated with images of the second modality to a coordinate space of the receiver, to transform the coordinate space of the receiver to a coordinate space of the transmitter, and to transform the coordinate space of the transmitter to the coordinate space associated with images of the first modality.

A method of calibrating a magnetic position sensor having a receiver and a transmitter, the method comprising:

• obtaining a first coordinate transformation between coordinate spaces of the receiver and transmitter;
• obtaining a second coordinate transformation between the coordinate space of the transmitter and a coordinate space of a target region, based on point fiducials positioned adjacent to the target region;
• obtaining a third coordinate transformation between a coordinate space of images associated with an imaging modality and the coordinate space of the target region, based on N-fiducials positioned within the target region;
• and
• based on the first, second, and third coordinate transformations, calculating a fourth coordinate transformation to associate the coordinate space of images associated with the imaging modality with the coordinate space of the receiver.

A method, comprising:

• registering a coordinate space associated with images of a first modality to a coordinate space of a magnetic position sensor, to obtain a first transformation;
• registering a coordinate space associated with images of a second modality to the coordinate space of the magnetic position sensor, to obtain a second transformation;
• and
• converting coordinates of images associated with one of the modalities to coordinates of images associated with the other one of the modalities based on the first and second transformations,
• wherein the position sensor comprises a receiver and a transmitter and wherein registering the coordinate space associated with images of the second modality to the coordinate space of the magnetic position sensor comprises:
• performing a transformation of coordinates of images associated with the second modality to the coordinate space of the receiver;
• and
• performing a rigid-body transformation from the coordinate space of the receiver to the coordinate space of the transmitter.

A method, comprising:

• registering a coordinate space associated with images of a first modality to a coordinate space of a magnetic position sensor, to obtain a first transformation;
• registering a coordinate space associated with images of a second modality to the coordinate space of the magnetic position sensor, to obtain a second transformation;
• and
• converting coordinates of images associated with one of the modalities to coordinates of images associated with the other one of the modalities based on the first and second transformations,
• wherein the magnetic position sensor includes a receiver and a transmitter, the method further comprising performing a calibration operation comprising:
• obtaining a first coordinate transformation between coordinate spaces of the receiver and transmitter;
• obtaining a second coordinate transformation between the coordinate space of the transmitter and a coordinate space of a target region, based on point fiducials positioned adjacent to the target region;
• obtaining a third coordinate transformation between a coordinate space of images associated with the second modality and the coordinate space of the target region, based on N-fiducials positioned within the target region;
• and
• based on the first, second, and third coordinate transformations, calculating a fourth coordinate transformation to associate the coordinate space of images associated with the second modality with the coordinate space of the receiver.