FDA bottleneck on 3-D ultrasoundgives way with TomTec clearance

FDA action comes in time for ACC meeting

Someone has lit a fire under medical device reviewers at the Foodand Drug Administration. While Congress debates reform of theagency and the way it approves medical devices, FDA staffers seemto have gotten the message and are cranking out product clearancesfor technologies that have languished in the review process foryears.

One of those technologies is 3-D ultrasound. The FDA in Decembergranted 510(k) marketing clearance to Acoustic Imaging of Phoenixfor its 3-D Ultrasound Imaging Workstation (SCAN 2/15/95). Theagency followed that action by giving its imprimatur last monthto another 3-D ultrasound workstation, TomTec Imaging's EchoView.The FDA's move comes at an opportune time for TomTec, just beforethis month's American College of Cardiology meeting in New Orleans,where the company will display the system.

EchoView is the image reconstruction component of TomTec's3-D and 4-D (3-D with movement) workstation technology (SCAN 5/19/93).TomTec is still awaiting clearance on EchoScan, an image acquisitionunit that works with EchoView. The company believes that FDA actionon EchoScan may come as early as this month.

EchoView is a desktop workstation that includes monitor, mouseand keyboard, with its CPU based on an Intel Pentium 90-MHz processor.It can accept data from any ultrasound scanner, although the company's510(k) application specifies that it must be used in conjunctionwith EchoScan, according to Larry Brennan, senior marketing managerat TomTec, of Boulder, CO.

When EchoScan is connected to an ultrasound scanner, sonographerscan either use special 3-D probes manufactured by TomTec or havethe option of three different types of carriage devices that attachto conventional transducers and move them in directions that allowthe acquisition of data that can be used to create 3-D reconstructions.The devices include:

• A parallel scan device that moves the transducer in equidistantsteps parallel to the organ or body part being imaged;

• A rotational device that rotates the transducer around acentral axis; and

• A sweep device that is held at an angle to the skin, thenpivots around the lens face while the tail of the probe movesin a sweeping motion.

A typical image acquisition takes five minutes, with reconstructionanother one or two minutes, using a proprietary surface-renderingalgorithm. Images can be reconstructed in several ways, includingcine reconstructions that can be gated to a patient's ECG andrespiration, adding a fourth dimension to static 3-D images. Thesystem does not support color Doppler, however, and depicts colorpixels in gray scale.

EchoView is expected to prove valuable in cardiology applications,according to Brennan. Cardiac surgery is one potential niche becausethe system can aid presurgical planning and postsurgical evaluation.It can show a surgeon a 3-D surface rendering of the heart fromthe anterior view of the organ rather than the posterior viewcommon with transesophageal probes, and can give surgeons a viewof moving organs such as a mitral valve opening and closing.

The list price of EchoView alone is $50,000 to $60,000. TomTechas not released a list price for EchoScan due to the component'sinvestigational status. TomTec will market EchoView and EchoScanthrough its direct sales force, which is the product of TomTec'smerger in 1993 with Prism Imaging and Freeland Systems (SCAN 1/19/94).TomTec also has OEM relationships with ultrasound vendors suchas Acuson, Hewlett-Packard, Toshiba, Diasonics subsidiary Vingmedand ATL subsidiary Interspec.

Like Acoustic Imaging, TomTec endured a long wait for 510(k)clearance, finally getting the FDA's nod nearly two years afterfiling the application. The agency's move may be a sign it isbeginning to loosen up its regulation of 3-D ultrasound, accordingto Brennan.

"My feeling is that the FDA is beginning to recognizethe consistency of 3-D reconstruction through a variety of differentmedical imaging techniques," Brennan said. "Our approachall along has been to base 3-D ultrasound reconstruction on othermedical imaging reconstruction algorithms like CT and MRI. Itappears in the wording (of the 510(k) notice) that the FDA, atleast in our case, believed that was appropriate."