In a twist of engineering that could redefine mobile medicine, researchers have built an ultrasound device that can be plugged directly into a smart phone's USB port. The system can capture ultrasound images of pregnant bellies and blocked carotid arteries, display them immediately on-screen, and even use the phone's capabilities to send that data just about anywhere in the world.

Physicians rely on ultrasound imaging for everything from monitoring fetal and cardiac health to providing guidance when placing catheters and central lines. Most of the time, however, the systems are large and cumbersome--handheld probes attached to wheeled computers the size of filing cabinets. They're also quite pricey: the larger, more versatile systems can cost $25,000 or more. Self-contained pocket-sized systems do exist but cost about $10,000. Nothing available today provides a low-cost, mobile solution that can be used remotely to both gather and transmit images.

The compact ultrasound probe, developed by computer engineers at Washington University, in St. Louis, has the potential to do all of that and more. Prompted by a grant program at Microsoft that called for the design of smart-phone-enabled medical devices, William Richard and David Zar started with an instrument that they developed five years ago: a $2,000 ultrasound probe that can plug into a laptop's USB port. Richard transferred all of the computing power into the probe itself and decreased its power draw to just half a watt; Zar created the necessary software and drivers.

To squeeze such capabilities into the probe, Richard and Zar had to make some concessions. In order to decrease its power requirements, Richard had to also decrease the amount of data that the instrument transmitted. The images themselves are smaller and less detailed than those from a full-size ultrasound. But while it has yet to undergo rigorous testing and comparisons, the researchers believe that its capabilities should be more than sufficient for many medical applications. They point to a number of potential uses: remote medicine for rural communities and developing nations, emergency imaging of patients en route to the hospital, battlefield medicine, and even home use in patients with chronic diseases. "Looking back on this 10 years from now," Richard says, "these are going to be used in places we never would have imagined."