Combining image based and inertial probe tracking

Abstract

An ultrasound imaging system with an inertial tracking sensor rigidly fixed to an ultrasound probe. In a first embodiment, a real-time pose estimation unit enhances image based tracking using the inertial data stream to calculate out-of-plane angles of rotation and determine an out-of-plane translation by iteratively selecting planes with the estimated out-of-plane rotations with varying out-of-plane offset, computing the differences between sub-plane distances computed by speckle analysis and the selected plane minimizing for the root mean square of the differences for all selected planes.In another embodiment, the real-time pose estimation unit enhances inertial tracking using the ultrasound image data stream to estimate an in-plane rotation angle; and substituting the in-plane rotation angle for an angle of rotation estimated using the inertial data stream.

What is claimed is: 
     
         1 . An ultrasound imaging system with enhanced ultrasound imaging probe tracking comprising:
 an ultrasound imaging probe providing an image data stream of sequential image planes;   an inertial tracker rigidly fixed to the ultrasound probe and providing an inertial data stream, the inertial tracker measuring acceleration and rotational velocity for three mutually perpendicular axes;   a real-time pose estimator that estimates a ultrasound probe pose by:   using the ultrasound image data stream to estimate an in-plane rotation angle; and   performing inertial tracking using the inertial tracking data stream, substituting the in-plane rotation angle estimated from the ultrasound image data stream for an angle of rotation estimated using the inertial data stream.   
     
     
         2 . The ultrasound imaging system of  claim 1 , wherein the inertial tracker comprises three mutually perpendicular linear acceleration sensors and three mutually perpendicular gyroscope sensors, and wherein the inertial data stream comprises acceleration data from the acceleration sensors and rotational velocity data form the gyroscope sensors. 
     
     
         3 . The ultrasound imaging system of  claim 1 , wherein the pose estimator is realized in a workstation. 
     
     
         4 . The ultrasound imaging system of  claim 3 , the workstation further comprises fusor that fuses the image data for a pose with an image volume to generate a fused image. 
     
     
         5 . A method for tracking an ultrasound imaging probe, comprising the steps of:
 receiving an image data stream comprising successive image planes from the ultrasound probe and an inertial data stream from an inertial sensor;   using the ultrasound image data stream to estimate an in-plane rotation angle; and   performing inertial tracking using the inertial tracking data stream, substituting the in-plane rotation angle estimated from the ultrasound image data stream for an angle of rotation estimated using the inertial data stream.   
     
     
         6 . The method of  claim 5 , wherein the angle of rotation estimates from the ultrasound imaging data are up-sampled to match the inertial sensor data sampling rate by interpolation.