In what might be a larger trend for makers of all kinds of screen-centric, processor-intensive technologies, engineers for portable ultrasound device maker Sonosite appear to be contemplating replacing the guts of their machines with Apple’s iPad or other tablet.

Sonosite describes itself as “the world leader and specialist in hand-carried and mountable ultrasound.” It’s got a market cap of more than $750 million, and it makes at least a half dozen different portable ultrasound machines. It’s not a new technology, but the ability to take it anywhere means it’s being used by doctors in unexpected contexts, such as daily monitoring of athletes and catching otherwise invisible cancers.

The just-released patent application indicates that Sonosite might be working on a case that not only connects the iPad directly to an ultrasound wand, but also contains additional hardware. This hardware almost certainly includes a battery but probably also additional chips to pre-process images generated by the ultrasound wand.

This would add additional bulk to the iPad, but it would still comprise a package that would probably be lighter and more portable than Sonosite’s current offerings.

More importantly, this design could take advantage of user-familiarity with Apple’s hardware. The company has already developed a touch-screen interface for at least one of its products, and has dabbled in educational products on the App store.

Many existing medical imaging systems incorporate commodity hardware. Given the versatility of smart phones and tablets, it’s worth asking whether this isn’t an indicator of a larger trend in which companies that used to invest heavily in custom hardware might pare down their R&D efforts so that they can concentrate on accessories and software that transform existing mobile devices.