An ultrasound is a straightforward procedure, but there are times when current technology isn’t ideal. The technique requires a probe to be pushed against the skin. In instances where an ultrasound needs to be performed, but the patient doesn’t tolerate probes against their skin, such as in babies or burn victims, a better technique was needed.
MIT has devised a new method and produced the first images of humans using a laser ultrasound. The new technique doesn’t require contact with the body to see inside the patient. The technique uses an eye and skin safe laser system. One laser in the system remotely generates sound waves that bounce through the body. The second laser remotely detects the reflected waves, and those are turned into an image similar to conventional ultrasound.
In testing, the researchers scanned the forearms of several volunteers and were able to observe tissue features like muscle, fat, and bone down to about 6cm in depth below the skin. The images were comparable to conventional ultrasound and were produced using remote lasers focused on the volunteer from half a meter away.
The team uses 1,550-nanometer lasers, which is a wavelength highly absorbed by water, and that is eye and skin safe. The pulsed laser in the systems is set at 1,550 nanometers, as is the second continuous laser. The second laser is a motion detector that measures surface vibrations on the skin.
The lasers produce images where the fat, muscle, and tissue boundaries are clearly visible. The team plans to improve the technique and refine it to resolve fine features. They also want to hone the laser’s detection capability. Down the road, they hope to deploy the units as a portable device.