High-performance hybrids get their ‘talking points’

GE's Infinia Hawkeye defines the value end of SPECT/CT devices. Until this spring, the Infinia was a single-slice. Now it's a quad-slice hybrid that delivers thick-slice CT data competitors refer to as "nondiagnostic." The middle ground is held by Siemens and Philips scanners sporting 16 or fewer slices. The high end of the spectrum is populated by a rarified breed of scanners more theoretical than real. Among these is Philips' Precedence 64, cleared by the FDA but not likely to enter production until next year at the earliest.

Ian Farmer, senior vice president and general manager of Philips nuclear medicine, described this system as a "talk release," which he defined as a product about which company executives and staff talk but that the firm doesn't yet make.

"We have internal programs under way to create that product," Farmer said. "We are talking about its availability. There are certain customers looking for availability in 2007. And we are ready to provide it in that time frame."

Philips has the hardware and the expertise to do it. The company's Gemini PET/CT scanner, billed as an open hybrid, has a space between the PET and the CT scanners, rather than butting the two together as competitors have done. Lopping off the six- or 16-slice scanner and replacing it with a 64-slice CT would seem relatively easy to do. But Philips is holding off until the clinical value of a 64-slice version is proved.

Farmer sees the need for such a system arising in hospitals, specifically ones involving patients who are "very sick" and can't hold their breath for the 20 or so seconds needed to perform a 16-slice scan. Breathholds drop to five or six seconds with a 64-slice scanner.

Such high-powered CTs also trump the 16-slice devices in image quality, especially when it comes to the coronaries. In a SPECT/CT configuration, such a device would allow accurate assessment of calcified and soft plaques in these vessels, he said. These data could then be correlated with the SPECT perfusion scan.

"This would give the physician an understanding of the complexity and severity of the stenosis causing a perfusion defect," Farmer said.

The software currently exists to produce a virtual SPECT/CT at this level of performance, achieved by conducting separate SPECT and 64-slice CT scans on a patient and merging the data. But using a combined instrument has advantages related to ease of use, diagnostic efficiency, and improved patient management.

Giving Philips pause, however, is the looming arrival of 64-slice PET/CT, which all vendors are either talking about or actually planning for release. Moves by Medicare and third-party payers to begin reducing SPECT reimbursement for cardiology, in the context of PET cardiac reimbursements that are now well north of $2000, have cardiologists giving PET a look-see.

Reimbursement considerations, however, must be weighed against the cost of the equipment on the nuclear medicine side and the availability of radiotracers. SPECT currently has the edge in both. Its cameras are priced at about half what PET instruments cost - and its radiotracers, technetium and thallium, are less expensive and easier to produce than PET's rubidium-82.

But, as with so many other facets of PET and SPECT, the radiotracer situation is anything but clear-cut. The short half-life of rubidium makes PET much more convenient for patients when performing rest/stress studies - PET exams take minutes rather than the needed hours for SPECT procedures. But SPECT is able to hold its own among providers with software that optimizes data processing, as well as scheduling expertise that can juggle a patient lineup and keep the flow moving.

In the end, the only sure determinant of this match between high-performance SPECT/CT and PET/CT will be time - not how long procedures take or how fast the data are processed, but its passage, which will allow the community to see which of these two gains a following. Until then, vendors will be doing a lot of talking.