1. A method of imaging a site of interest in a body using an ultrasound probe, the ultrasound probe comprising a plurality of ultrasound transducer elements, the method comprising: obtaining an ultrasound image of a pass zone of the body between the site of interest and the ultrasound probe, the image including the site of interest and a plurality of tissue regions in the pass zone; determining, from the image, boundaries of a selected tissue region in the pass zone; computing respective focusing delay times for each transducer element associated with an ultrasound beam passing through the selected tissue region, the computed focusing delay times computed based, at least in part, on a speed of sound in, and the determined boundaries of, the selected tissue region, wherein the speed of sound is a speed other than an average speed of sound in body tissue; and conducting an ultrasound imaging scan of the pass zone employing the computed focusing delay times.