GE evolving handheld ultrasound with advances in nanotechnology

PDA-like device based on piezoceramics alternative

Following a universal trend to make electronic devices smaller, GE is developing a prototype of a handheld diagnostic ultrasound unit. The system is similar in shape to the popular palm-based PDAs. The ultrasound image appears on an LCD built into the top half of the device.

Until now the company has focused mostly on cart-based ultrasound equipment. But its launch of LogiqBook in December 2002 set the stage for GE's entry into the compact ultrasound systems market. The company sold 1000 of the laptop-sized systems in the first nine months it was available, mostly for radiological applications. A handheld product would extend those applications, according to Jeff Peiffer, GE Medical Systems manager of the Americas for compact ultrasound.

"There are numerous advantages to using compact ultrasound for guidance in vascular access and biopsies as well as other, less invasive, surgical procedures," he said.

Developmental work on the handheld system is under way at GE Global Research, the company's R&D network with facilities in the U.S., India, and China, and headquarters in Niskayuna, NY. Commercial results from those efforts could be several years away, according to Peiffer. Engineers are still tweaking the new transducer technology underlying this new product.

"Piezoceramics have been (the core of) the transducer of choice for many years," said Scott C. Donnelly, director of GE Global Research. "Now we are looking at MEMS (micromachined electromechanical systems)."

MEMS nanotechnology involves the placement of mechanical elements, sensors, actuators, and electronics on a common silicon substrate. Components are made using micromachining methods that selectively etch or add structural layers to silicon wafers to form mechanical and electromechanical devices. GE's transducer would be based on a specific type of nanotechnology, called cMUT (capacitive microfabricated ultrasonic transducers).

GE's use of MEMS to create a cMUT allows the transducer and electronics to be combined on the same circuit. This offers two benefits, according to Donnelly: low-cost manufacturing and portable applications.

"There are a lot of things you can do (with MEMS), given the granularity and different ways of dynamically configuring these arrays, that you have not had with a piezoceramic device," he said.

This and other forms of nanotechnology have become a priority at GE Global Research.

"(Nanotechnology will be) one of the biggest enabling technologies we have seen, fundamentally changing our laboratory and changing the things we can do going into the future," Donnelly said.

Nanotechnology is already having an effect on products being marketed by GE Medical Systems. It is being incorporated into CT detectors and advanced ultrasound transducers, according to Peiffer.

"Matrix arrays (for the flagship Logiq 9 system) couldn't be fabricated without that kind of technology," he said.

Competition to get more technology into ever smaller packages will drive the medical imaging industry's development of nanotechnology. At the 10th Congress of the World Federation of Ultrasound in June, a Canadian firm called Sensant displayed clinical images obtained with its own brand of tiny silicon structures (SCAN 6/11/03). Sensant engineers worked with staff at Esaote in Genoa, Italy, and radiologists at Valduce Hospital in Como, Italy, to generate images of the carotid artery, breast, and musculoskeletal system.

Sensant promotes cMUT as enabling novel transducer geometries that allow thinner imaging planes and increased penetration. These could improve the detection of breast tumors and help physicians differentiate benign irregularities from cancerous tumors. The technology improves the quality of images obtained using contrast agents, according to Sensant, and could support a new generation of contrast-enhanced imaging applications.

On-chip electronics, new array designs, and novel system architectures that are possible with cMUT also offer new opportunities for the development of 3D ultrasound systems, according to the company.

GE's development of cMUT for handheld ultrasound is especially significant. So far, only specialty ultrasound players have produced such systems. But market leader Sonosite has sold more than 11,000 of its highly portable units, in and outside of radiology (SCAN 4/30/03), which has caught GE's attention.

Sonosite has evolved its technology into several forms, each optimized for an application, from vascular and general imaging to cardiology. Its most recent development, called Titan, operates as both a handheld unit and as part of a docking station, which provides additional flexibility. The docking station allows individual images and video sequences to be downloaded into a PC or information system.

Sonosite was spun off from ATL in 1998 before ATL was acquired by Philips Medical Systems. At the time, handheld ultrasound systems were viewed as being outside the traditional bounds of diagnostic ultrasound, and they were being groomed for sale mostly to general practitioners and other physicians who would use them as part of their daily routine. Reimbursement problems doomed that idea, leading Sonosite strategists to promote their products for more conventional applications. To date, none of the major ultrasound vendors has released a handheld unit.

GE Medical Systems is the first to publicly acknowledge its interest in developing such a device. The depth of engineering and experience at GE could be leveraged to manufacture a product with extraordinary capabilities, Peiffer said. Technologies from high-end ultrasound systems, for example, might be ported to the handheld unit, as has been done in migrating 3D, for example, from the Logiq 9 to the LogiqBook. Following progress made at the high end of GE's ultrasound product line, therefore, might provide a glimpse of what may be available on GE's handheld system when it debuts.

"This past month we added voice control to the Logiq 9, so you can tell it to turn color on or change the gain or annotate, save, freeze, or send images to print," Peiffer said. "All this is migratable."