Ultrasound scanner differs from other 3-D systemsA new player has entered the burgeoning market for 3-D ultrasound with a powerful new scanner unlike any other 3-D system on the market. Volumetrics Medical Imaging debuted at last month's American
Ultrasound scanner differs from other 3-D systems
A new player has entered the burgeoning market for 3-D ultrasound with a powerful new scanner unlike any other 3-D system on the market. Volumetrics Medical Imaging debuted at last month's American College of Cardiology meeting with Model 1, a dedicated 3-D ultrasound scanner that produces 3-D images in a single real-time acquisition, rather than through the reconstruction of 2-D slices.
Volumetrics of Durham, NC, launched Model 1 at a symposium held March 28 in conjunction with the ACC conference in Atlanta. Volumetrics also displayed Model 1 in its booth at the meeting. Although the scanner was formally introduced last month, initial shipments began in October 1997, with echocardiography the first target market for the system. The scanner received 510(k) clearance in 1997.
Volumetrics was founded in 1991 as 3-D Ultrasound to commercialize work done on 3-D ultrasound technology at Duke University in Durham. Duke researchers had invented a technology referred to as receive-mode parallel processing, a software processing method that enables the formation of multiple lines of data from each transmission signal.
Receive-mode parallel processing enables Model 1 to approach 3-D ultrasound in a totally different way than other scanners and workstations on the market. These systems are based on conventional 2-D scanning technology, and create 3-D images by reconstructing 2-D slices of ultrasound data. One drawback to this approach has been long reconstruction times, but increases in computer horsepower are helping vendors reduce reconstruction times to clinically acceptable levels.
The 3-D reconstruction approach has one other disadvantage, however, especially when clinicians are trying to quantify volumes in the body, such as the heart or other organs, and the impact of pathology on the size and function of those volumes. Quantitation with 3-D reconstructions is cumbersome, time-consuming, and requires a major investment in user training, according to Volumetrics. Meanwhile, 2-D quantitation also has disadvantages, especially because the 2-D slices used for quantitation aren't registered to the rest of the volume being imaged, according to John Oxaal, president and CEO of Volumetrics.
"The slice in that volume is by itself; it's not registered to the rest of the data that is in there," Oxaal said. "If you do a study six months later, how do you know that you will get exactly the same view that you did today?"
Model 1 addresses the problem by acquiring all the data needed to create a 3-D image in essentially a single acquisition in real time. Such a task requires a phenomenal amount of horsepower, but Model 1 has the architecture to accomplish it: The system uses a beamformer architecture that consists of 16 parallel-processed beamformers for each of its 256 receive elements, resulting in a system with the equivalent of 4096 channels.
In addition to its powerful beamformers, Model 1 employs 2-D matrix arrays to capture data. This enables the system to transmit and receive ultrasound waves in a pyramid-shaped volume, compared with the pie-shaped 2-D slices captured with conventional scanners.
Dynamic slices. The net result of all this technology is a scanner that can acquire and display dynamic organs such as the heart in multiple views. Model 1 can display a typical echocardiography study, for example, in multiple dynamic slices displayed simultaneously on its monitor, with each slice representing a different plane through the heart.
In addition to making it easier for clinicians to visualize data, Model 1 contains the tools necessary to quantify it. Model 1's clinical users have demonstrated the use of the system to carry out measurements of the heart's pumping efficiency, such as left ventricular ejection fraction, left ventricular perfusion with contrast agents, and left ventricular wall motion, as well as measures of right ventricular function. Not surprisingly, Volumetrics has targeted echocardiography as the first use for the system, due in large measure to the scanner's ability to quantify cardiac studies.
"The advantages of real-time 3-D are most evident in the heart," Oxaal said. "Quantitation is a big issue for cardiology. Being able to calculate ejection fractions without observer variability is a big deal as well."
Model 1's advanced capabilities have apparently piqued the interest of cardiologists, and Volumetrics counts some of the most prominent cardiologists in the U.S. among its users. The company's scientific advisory board includes Dr. Anthony DeMaria of the University of California, San Diego; Dr. Nelson Schiller of the University of California, San Francisco; Dr. David Sahn of the Oregon Health Sciences Center in Portland; Dr. Joseph Kisslo of Duke University; and Dr. Arthur Labovitz of St. Louis University.
In the near future, Volumetrics would like to expand Model 1's focus into other applications, Oxaal said. Fetal and neonatal imaging are the next logical areas, although the company's technology has potential use throughout general ultrasound imaging due to its ability to provide reproducible quantitative measurements.
"Radiology ultrasound also needs to be more quantitative," Oxaal said. "There are 15 diseases that make the kidney bigger and five diseases that make the kidney smaller, and you can't tell from one slice how big the kidney is."
Volumetrics is handling sales of Model 1 in the U.S. directly, and has a relationship with Ecoscan of Zug, Switzerland, for European distribution. The company declined to release the list price for Model 1, but Oxaal said it is well under the $350,000 price point common among super-premium scanners.
For postprocessing of Model 1's 3-D ultrasound images, Volumetrics has established a relationship with 3D EchoTech, a German company that was formed in 1995 by former employees of 3-D ultrasound developer TomTec. 3D EchoTech has developed image processing software, called 3-D FreeScan, that takes 3-D digital data sets and formulates them into reconstructed 3-D images similar to those found on other 3-D scanners and workstations.
3D EchoTech's first versions of 3-D FreeScan targeted non-cardiac applications, but the firm is now moving into the echo market through its relationship with Volumetrics. The company displayed its 3-D workstation in the Volumetrics booth at the ACC meeting, and plans to begin sales as soon as it receives 510(k) clearance from the Food and Drug Administration, according to Ricardo Cabrera, the company's director for sales and marketing of the Americas region.