Electronic Innovation Spearheads Medical Imaging Revolution

DN Staff

February 15, 2010

8 Min Read
Electronic Innovation Spearheads Medical Imaging Revolution

Some day, when an NFL quarterback wobbles off the field after a hard hit in the head, doctors will be able to quickly check for brain injuries on the sideline using portable imaging devices. In the days following the injury, they might also use the imagers for up-to-the-minute follow-ups, the better to track the player's recovery.

"New portable technologies could allow them to check on a daily basis if they wanted to," says Arthur DiMartino, CEO of TechEn Inc., manufacturer of a portable imaging technology called diffuse optical tomography (DOT).

That, of course, is a far cry from what happens today. These days, real looks inside the brain are few and far between. That's because today's magnetic resonance imagers (MRIs) cost more than a million dollars and take up as much as 300 sq ft of floor space. "A pro football team isn't going to go back every day to check Ben Roethlisberger's concussion," DiMartino says. "It just doesn't happen that way."

That, however, is changing. Accessible imaging is fast becoming the norm in patient care. Tried-and-true ultrasound technologies, once limited to cart-based systems, have moved off the cart and into portable laptop computers. CT scanners are also finding new homes outside the hospital.

The result is that medical imaging is moving into locales that were undreamed of a decade ago. Handheld ultrasound systems are appearing in war zones, disaster sites and even on Mount Everest expeditions. Meanwhile, lower cost electronics are enabling technologies such as CT scanning to move into medical practices. Experts say all of this is happening as a result of new digital processors and analog chips.

"We're seeing a big trend toward integration of semiconductor components across the different modalities of imaging," says Veronica Marques, business development manager for Texas Instruments' Medical Business Unit. "It all comes back to what the patient is asking for - more accessibility, more affordability and better diagnostics."

Imaging Revolution

Indeed, new levels of electronic integration are revolutionizing medical imaging. Ultrasound technology has been the biggest beneficiary of that integration, with dramatic reductions in cost and size. In the past 10 years, ultrasound has transitioned from a bulky, cart-based technology to a sleek, laptop-based mode. And in tandem with that size change, performance has evolved, too.

"The capabilities of the portable units are approaching the capabilities of the cart-based systems," says Scott Pavlik, marketing manager for the Health Care Segment team at Analog Devices Inc. "A lot of the same imaging that used to be done exclusively by cart-based systems can now be done on a laptop."

In particular, laptop-based ultrasound systems can now do color Doppler imaging, which makes it possible to perform blood flow analysis in cardiac applications. As a result, portable ultrasound is now finding use in the diagnosis of strokes, carotid artery blockages, heart disease, abdominal aortic aneurysms and peripheral artery disease.

SonoSite Inc. makes such portable ultrasound systems for use in doctor's offices, as well as at the point of care, whether it's an accident scene or patient's bedside. Meanwhile, Signostics Inc. has taken the portability factor a step further, shrinking its mobile ultrasound system down to the size of an iPod. The company says that doctors can wear the half-pound device around their necks like a stethoscope.

Similarly, CT scanning has evolved. Electronic integration has enabled CT machines to dramatically boost their so-called "slice counts," which enables the machine to quickly take more detailed pictures inside the body.

"Ten years ago, you had mostly single-slice machines," Pavlik says. "Four slices was a big deal. Then the slice counts exploded. The progression went from four to eight to 16 to 64 to 256. Now, you've even got 320-slice machines."

Experts say multi-slice machines enable radiologists to see more volume in a single pass. Higher-slice-count machines, for example, can "see" a bigger portion of the heart without having to go back and forth multiple times.

"Slice count improvements are boosting image quality," Pavlik says. "Some of the machines can do a full cardiac image in a single rotation. That means you can do the image faster and move more patients through the machine."

While existing technologies are being improved, others are emerging. TechEn's Continuous Wave 6 (CW6) diffuse optical tomography (DOT) system, which uses near infrared spectroscopy to create images, is being employed in stroke rehabilitation, breast imaging, concussion analysis and a host of other medical applications. TechEn engineers say the device is an adjunct to, rather than a replacement for, MRI. Its lower cost (less than one-quarter that of MRI) and smaller size (less than one-tenth of MRI) make it an alternative in situations where portability and frequent follow-up measurements are called for.

"When someone is in stroke rehabilitation, the DOT instrument would allow you to monitor the patient on a monthly basis in the doctor's office," says DiMartino of TechEn. "So this would allow a shift from the more expensive technology to a more appropriate technology."

DiMartino says technologies such as DOT might one day be used on the field at professional sporting events. Or, in the doctor's office, he says, it would enable physicians to do daily checks on patients, such as professional athletes with acute injuries.

"We're moving the technology closer and closer to the patient," he says. "The idea is to provide specialized treatment to patients with specific conditions."

Electronic Consolidation

The key to all of these innovations lies in the ongoing integration of electronics, engineers say.

In CT scanning and ultrasound systems, design engineers have relied on suppliers to pack more electronics into less real estate on so-called "analog front end" chips. Those devices - which typically contain a low-noise amplifier, voltage-controlled attenuator, programmable gain amplifier and analog-to-digital converter - have changed dramatically since 2004. They've shed a monumental amount of space, going from a full-scale, handheld printed circuit board carrying 40 components to a single chip measuring as small as 9 x 9 mm (less than .50 x .50 inch). Texas Instruments' AFE5801 and AFE5851, as well as ADI's AD9272 and AD9273, incorporate all the necessary components in single-chip designs.

"By integrating more functionality onto a small IC, we've taken what used to be a complete PC board down into a very small form factor," Pavlik says. "So now, the manufacturers are able to integrate Doppler processing into a portable system, so they have a laptop-sized machine that can be used for cardiac applications and blood flow analysis. That couldn't have been done a few years ago." Pavlik adds that the integration of today's analog front ends is also a key to enabling the explosion of slice counts in CT scanning.

Still, analog front ends aren't the only enabling technologies in medical imaging. Engineers say digital signal processors (DSPs) have also played a big role. TechEn's bone densitometer and its diffuse optical tomography system, for example, rely heavily on 16-bit microcontrollers containing DSP cores from Microchip Technology Inc. Known as dsPIC, the devices incorporate the kinds of number-crunching capabilities needed for the signal processing chores in both kinds of systems. TechEn engineers estimate that the DSP cores chug through about 10 million operations per second - about 10 to 20 times more than they would get from a conventional microcontroller.

"In order to make the measurements happen in a real time fashion, we need the DSP functionality," says Bill Johnson, chief engineering officer for TechEn. "With DSP, we can make a bone density measurement in about 10 seconds. Whereas without DSP, we'd be looking at about five minutes."

Beyond Imaging

The bottom line, say experts, is that medical imaging is moving to a new era. Makers of imaging systems aren't simply boosting performance, they're targeting cost cutting and portability, which is expected to be critical as health care evolves.

"Sure, there's still a lot of emphasis on the image itself, but more and more, the issues will involve accessibility and cost," Pavlik says. "The ability to make the technology faster, and therefore make it available to more patients, is going to be critical."

Indeed, accessibility is going to be more important as Baby Boomers age. According to figures from the World Health Organization, the number of people aged 60 and older is set to balloon from 650 million in 2006 to 1.2 billion by 2025. Many of those individuals will inevitably receive health care in the doctor's office or at home, especially as rising costs make hospital care more difficult to obtain.

"The idea is to have the equipment closer to the first contact with the patient," says Steve Kennelly, manager of Microchip's Medical Products Group. "Doctors won't want to refer patients outside their practice, and they're going to want the equipment to be small, so they can move it from room to room."

To accomplish that, medical equipment manufacturers will continue to look to suppliers. Continued analog integration and more powerful processing are expected to be key.

"Innovations in process technology are going to continue to benefit medical equipment designs," says Marques of Texas Instruments. "That's how you bring the equipment down from the size of a room to the palm of your hand."

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