1. A method of acquiring an extended field of view ultrasound image, comprising: acquiring a first plurality of spatially overlapping ultrasound image data sets by moving an ultrasound scanhead along a target area; acquiring a second plurality of spatially overlapping ultrasound image data sets by moving the ultrasound scanhead along the target area, the acquisition of the ultrasound image data sets in the second plurality being interspersed with the acquisition of the ultrasound image data sets in the first plurality, the ultrasound image data sets in the first plurality containing substantially more image data than the ultrasound image data sets in the second plurality; using the ultrasound image data sets in the second plurality to track the movement of the ultrasound scanhead based upon the respective locations of corresponding speckle in the ultrasound image data sets in the second plurality; and combining at least some of the ultrasound image data sets in the first plurality based on the tracked movement of the ultrasound scanhead to create the extended field of view ultrasound image.