While this might sound like a comic book villain's torture device, according to researchers at Washington University in St. Louis, you'd only feel a slight warming sensation from the focused ultrasonic blasts heating up your vessels. Meanwhile, infrared laser pulses bounced off the warmed blood would be picked up by the ultrasound, delivering real-time flow data.New Scientist likens it to dribbling a drop of ink in a stream of water to determine the speed and direction of flow. Except, y'know, with hot blood instead of ink.
In experiments, the technique accurately measured blood flow as slow as a quarter-millimeter per second. By comparison, current ultrasound technique can't accurately detect anything under 10 millimeters per second. Next up: human testing. And apparently it won't hurt a bit. More here.