A method of imaging a blood vessel includes delivering a bubble-based contrast agent within the vessel and positioning at least one ultrasound device in the vicinity of the bubble-based contrast agent within the vessel. A first burst of low-frequency ultrasound energy can be delivered to excite the bubble-based contrast agent into oscillation within the vessel, and a second burst of high-frequency ultrasound energy can be delivered at the excited bubble-based contrast agent. A return signal from the burst of high-frequency ultrasound energy can be received and processed to obtain one or more images.