Technology Review:

Earlier this year, vascular surgeon John Martin was testing a pocket-sized ultrasound device developed by Butterfly Network, a startup based in Guilford, Connecticut, that he’d just joined as chief medical officer.

He’d been having an uncomfortable feeling of thickness on his throat. So he oozed out some gel and ran the probe, which is the size and shape of an electric razor, along his neck.

On his smartphone, to which the device is connected, black-and gray images quickly appeared. Martin is not a cancer specialist. But he knew that the dark, three-centimeter mass he saw did not belong there. “I was enough of a doctor to know I was in trouble,” he says. It was squamous-cell cancer.

How many stories have we seen where an Apple Watch notifies someone of an abnormal heart rhythm? That’s just the start.

The iPhone, add-on devices like this ultrasound unit, Apple Watch and, of course, HealthKit, are changing the health care landscape.