A tracking system for ultrasound imaging includes an imaging probe which acquires ultrasound image information including a plurality of ultrasound image frames; an inertial measurement unit coupled tothe imaging probe and which synchronously acquires tracking information including a plurality of tracking frames indicative of motion of the imaging probe; and a controller. The controller is 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, and determine a similarity value based upona comparison of the at least two ultrasound image frames. The controller is configured to compute whether the similarity value (Cframe) is less than a similarity threshold value (Cthresh), and selectfirst or second pose estimation methods, each different from each other, based upon results of the computation of whether the similarity value (Cframe) is less than the similarity threshold value (Cthresh).