Germans explore new echo dimension

A group of former Kontron engineers with experience in three-dimensionalMRI processing has built an innovative four-dimensional ultrasoundscanner. The fourth dimension of time (and therefore motion) isessential in echocardiography, which is the first targeted applicationfor this technology.

The image processing engineers left Kontron following its acquisitionin 1989 by BMW (SCAN 4/26/89). They formed their own company,Tomographic Technologies (TomTec) of Munich, in May 1990 to commercializepatented 4-D ultrasound technology, said Peter Klein, presidentand co-inventor of the 4-D process.

TomTec displayed its Echo CT system at the American Heart Associationmeeting in Anaheim last week. The unit has not yet been approvedby the Food and Drug Administration. TomTec's first four clinicalbeta sites for the 4-D scanner were scheduled to receive theirmachines shortly after the AHA meeting.

The first U.S. clinical site will be at the University ofKentucky in Lexington. Two scanners will be placed in Europe andone in Japan. TomTec will establish a direct U.S. subsidiary towork with clinical sites and eventually sell the system. Thiscompany should be formed within the next two months, Klein said.

Several ultrasound vendors, including Kretztechnik, Philipsand Dornier, have shown 3-D ultrasound reconstruction work. TomTec,however, has taken a dramatic leap forward with the inventionof a unique transesophageal (TEE) probe capable of visualizingthe entire heart in motion.

A key feature of this probe is that it is flexible enough toenable insertion into the esophagus but stiffens when inside thebody. The probe must be stiff so that a motorized, computer-controlledtransducer can slide up and down, taking full-beat slices of theheart.

"There are 150 very thin slices of the beating heart.All that information is placed in computer memory. We are thenable to reconstruct any plane of the beating heart," Kleinsaid.

Each slice is actually a different heart cycle. TomTec usesa computer algorithm to compare cycles and discard those thatvary beyond acceptable parameters. If a particular slice is notsimilar enough to previous slices of the heart cycle, the transducerretakes the cine image.

"The slices all look the same. The cube is in three dimensionsand we have 30 of these cubes in the fourth dimension," Kleinsaid.

One reason TomTec was able to develop this complex technologyin less than two years was that research was limited to the specialtransducers, computer processing software and console display.The firm uses an existing ultrasound engine purchased from a majorultrasound vendor and a standard 486-based computer architecture,which is built into the scanner.

TomTec has not implemented color-flow Doppler on the Echo CT,but plans to do so before the American College of Cardiology conferencein April. The system is expected to sell for about $250,000, hesaid.

Given the importance of motion in ultrasound imaging, thereare likely to be more organ-specific applications of the 4-D technologyin the future, Klein said. TomTec has already developed a scannerdedicated to 4-D imaging of carotid arteries.

Pharmaceutical firms are interested in developing quantificationof blood-flow volume in order to test their drugs. TomTec is formulatingquantification technology for its 4-D scanner at a German universityin collaboration with a drug company, Klein said.

TomTec will not have a booth at the Radiological Society ofNorth America meeting in Chicago this week but might do so in1992, Klein said.

"We could end up with radiology system that is a CT scannerusing ultrasound. It might have six different probes for the heart,carotids, gynecology and other applications," he said.