A tracking system (100, 500) for ultrasound imaging, the tracking system comprising: an imaging probe configured to acquire ultrasound image information including a plurality of ultrasound image frames; an inertial measurement unit (IMU, 111, 540) coupled to the imaging probe and configured to synchronously acquire tracking information including a plurality of tracking frames indicative of motion of the imaging probe; and a controller (120, 510) configured to: obtain the ultrasound image information for at least two of the plurality of ultrasound image frames from the plurality of ultrasound imaging frames, determine a similarity value based upon a comparison of the at least two ultrasound image frames, compute whether the similarity value (C frame) is less than a similarity threshold value (C thresh), and select first or second pose estimation methods for the imaging probe each different from each other based upon the results of the computation of whether the similarity value (C frame) is less than the similarity threshold value (C thresh); wherein the controller is configured to select the first pose estimating method when it is determined that the similarity value (C frame) is less than the similarity threshold value (C thresh) and wherein the first pose estimating method determines pose by integrating the tracking information from the IMU and storing the result in a memory of the system; and wherein the controller is configured to select the second pose estimating method when it is determined that the similarity value (C frame) is not less than the similarity threshold value (C thresh); characterised in that the second pose estimating method determines pose based upon an image-based bias correction of integrated tracking information. an imaging probe configured to acquire ultrasound image information including a plurality of ultrasound image frames; an inertial measurement unit (IMU, 111, 540) coupled to the imaging probe and configured to synchronously acquire tracking information including a plurality of tracking frames indicative of motion of the imaging probe; and a controller (120, 510) configured to: obtain the ultrasound image information for at least two of the plurality of ultrasound image frames from the plurality of ultrasound imaging frames, determine a similarity value based upon a comparison of the at least two ultrasound image frames, compute whether the similarity value (C frame) is less than a similarity threshold value (C thresh), and select first or second pose estimation methods for the imaging probe each different from each other based upon the results of the computation of whether the similarity value (C frame) is less than the similarity threshold value (C thresh); wherein the controller is configured to select the first pose estimating method when it is determined that the similarity value (C frame) is less than the similarity threshold value (C thresh) and wherein the first pose estimating method determines pose by integrating the tracking information from the IMU and storing the result in a memory of the system; and wherein the controller is configured to select the second pose estimating method when it is determined that the similarity value (C frame) is not less than the similarity threshold value (C thresh); characterised in that the second pose estimating method determines pose based upon an image-based bias correction of integrated tracking information. obtain the ultrasound image information for at least two of the plurality of ultrasound image frames from the plurality of ultrasound imaging frames, determine a similarity value based upon a comparison of the at least two ultrasound image frames, compute whether the similarity value (C frame) is less than a similarity threshold value (C thresh), and select first or second pose estimation methods for the imaging probe each different from each other based upon the results of the computation of whether the similarity value (C frame) is less than the similarity threshold value (C thresh); wherein the controller is configured to select the first pose estimating method when it is determined that the similarity value (C frame) is less than the similarity threshold value (C thresh) and wherein the first pose estimating method determines pose by integrating the tracking information from the IMU and storing the result in a memory of the system; and wherein the controller is configured to select the second pose estimating method when it is determined that the similarity value (C frame) is not less than the similarity threshold value (C thresh); characterised in that the second pose estimating method determines pose based upon an image-based bias correction of integrated tracking information. wherein the controller is configured to select the first pose estimating method when it is determined that the similarity value (C frame) is less than the similarity threshold value (C thresh) and wherein the first pose estimating method determines pose by integrating the tracking information from the IMU and storing the result in a memory of the system; and wherein the controller is configured to select the second pose estimating method when it is determined that the similarity value (C frame) is not less than the similarity threshold value (C thresh); characterised in that the second pose estimating method determines pose based upon an image-based bias correction of integrated tracking information.