Three-dimensional ultrasound could increase power and expand applications for the rapidly growing imaging modality. Researchers working with Philips Ultrasound, an early developer of 3-D ultrasound, are peering into parts of the body that were inaccessible with standard ultrasound scanners, said Ralph Ranalli, transducer product manager.
A market for this image processing technique may develop quickly if clinical studies show that 3-D ultrasound provides new diagnostic information.
Use of 3-D image processing in computed tomography gained acceptance slowly because radiologists, the primary users of medical imaging equipment, did not consider the technique particularly useful in a clinical setting. The market for 3-D and multiplanar reconstruction in CT was driven by referring physicians, particularly surgeons, who found the reader-friendly images useful.
Ultrasound is a latecomer to 3-D. Clinical efforts to prove its applications are in early stages, but initial results with the Philips system indicate practical diagnostic benefits of post-scanning reconstruction, Ranalli said. Ranalli is based at Philips Ultrasound's worldwide headquarters in Santa Ana, CA. The 3-D technology was developed at the Dutch vendor's research facility outside Paris.
Applications of ultrasound are fundamentally limited by its inability to image through bone. Ultrasound reconstruction may circumvent this difficulty in some cases by first acquiring the volumetric image data from an accessible angle and then creating an image slice across the original scan planes. The definition of a diagnostic plane is, in effect, broadened and distinguished from the scan plane.
"There is a separation of the connection between the transducer and the (diagnostic) plane," Ranalli said. "Static information in the volume can be re-explored. That can be significant, particularly since orientations may be changed."
For example, Philips has created ultrasound images of a neonatal brain that were previously not possible because sound waves can only enter the head from a particular angle through the soft spot in the skull.
"No one has ever seen that view (in standard ultrasound scanning), because you can't get to that scan plane. But you can sweep the 3-D volume line by line and then use the computer to reconstruct the plane," Ranalli said.
Philips is working on two types of 3-D ultrasound techniques:
Multiple diagnostic planes are presented in a perspective fashion to create the impression that the user is working with a volume. That volume can be re-sliced, pulled apart and rotated in near real-time.
BRIEFLY NOTED:
The system introduction is a response to market demand for less expensive MRI systems in low-throughput situations, said John Falconi, manager of mid-field MRI systems. The Encore is appropriate for sites with throughput of fewer than 10 patients per day, he said.
With its lower cost, the Encore should break even at about four patients a day. It is upgradable to the MR Max Plus if clinical needs change, he said.
The new agent is designed to improve anatomic definition and address the problem of bowel gas obscuring structures during abdominal scanning. About 4 million abdominal ultrasound exams are performed in the U.S. each year, according to MBI.
