L. Wang, J. Xia, J. Yao, KI Maslov, LV and Wang
Now there is a better way to spy the blood in your veins. Doctors already have two techniques to monitor obstructions in blood vessels, but both have limitations. The first, the ultrasonic Doppler imaging, involves irradiating tissue with ultrasonic waves; the waves that reflect off the blood flowing acquire a Doppler shift, which can be used to take blood and calculate its speed. Doppler can not distinguish the blood flow to surrounding tissue but unless it moves quickly, which makes the blood vessels invisible minors. The second technique, photoacoustic imaging, uses an infrared laser which, when absorbed into the blood, heats. The sudden expansion creates a resulting pressure wave that can be detected outside the body. photoacoustic imaging chooses the blood vessels better, but it can not see cast in a continuous stream. In a study published today in Physical Review Letters , the researchers combined both techniques, using the fact that ultrasound also has a slight warming effect; periodic pulsed ultrasound creates hot spots in blood vessels. By tracking the movement of these hot spots (in yellow above) using photoacoustic imaging, the team was able to calculate blood flow rates, even when he moved slowly through small vessels as capillaries. The researchers hope that their technique can help functional brain imaging, helping the detection of cancer and monitoring treatment, and that doctors detect atherosclerosis before a patient has a heart attack.
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