Coincidence detection technology may be what the doctor ordered for PET

Increase in users should help FDG supply

Sometimes a competitor can turn out to be your best ally in business. Take the case of PET and coincidence detection imaging using gamma cameras. At first glance, PET appears to be under assault by its nuclear medicine cousin. A closer look, though, shows that coincidence gamma camera imaging may encourage reimbursement for PET and justify a more widespread supply of fluorodeoxyglucose (FDG), the main PET radioisotope.

Dual-head gamma cameras can now mimic the coincidence circuitry of tomographic PET systems in order to perform high-energy functional imaging of tumors. It is PET with a twist, though. The cameras are used for both conventional nuclear medicine and high-energy work.

"This is coincidence detection of the photons-true PET imaging," said Dr. Edward Coleman, director of nuclear medicine at Duke University in Durham, NC. "The resolution of these camera-based systems is equal to if not better than the present dedicated PET scanners."

PET has made scant progress as a mass clinical modality in the nearly two decades since its development. Coincidence imaging may change that. Less than 100 dedicated PET systems are installed in the U.S. today. That installed base could be matched and bettered by coincidence gamma cameras in only their first year on the market.

Nuclear medicine vendor ADAC Laboratories of Milpitas, CA, started shipping gamma cameras featuring its Molecular Coincidence Detection (MCD) option last November. Interest has been high among standard nuclear medicine customers, said Ian Farmer, senior vice president and general manager for ADAC's nuclear medicine business.

ADAC has had bookings of about 80 MCD systems to date, Farmer told SCAN last week, and the company has shipped 45 to 50 systems and installed 35 to 40 units around the world. Unlike PET, which is selling faster in international markets, the majority of MCD sales have been in the U.S.

Since these cameras can perform standard nuclear imaging, users are not dependent on PET reimbursement or throughput to show a profit, Farmer said.

"A site might start off doing one (FDG procedure) a week," he said. "You could never justify a PET system on the basis of one scan a week, but you can also use the gamma camera in nuclear medicine. Then, as you build referral patterns, you can switch the mix on that gamma camera to do up to 100% FDG imaging."

U.S. sluggishness. At one time, more PET systems were sold in the U.S. than in the international market, said Terry Douglass, president of PET manufacturer CTI of Knoxville, TN. Now about 75% of dedicated PET systems are sold outside the U.S.

"Our business outside of the U.S. is really good right now," he said. "Germany is going very well, and Asia is beginning to show growth as well. The U.S. has been lagging behind for the last several years in PET."

CTI's good fortune in PET is being shared by the nuclear medicine division of Siemens Medical Systems in Hoffman Estates, IL, which sells PET cameras manufactured by CTI PET Systems, a joint venture between CTI and Siemens. The company's PET business has been profitable for the last several years and is growing at a rate of 30% this year, according to Randy Weatherhead, vice president of marketing. The company's 75% market share in PET camera sales means that it has the volume to invest in the modality yet remain profitable, he said.

Weatherhead said that his company's PET business has improved further in the wake of turbulence at two of its major competitors in PET, GE Medical Systems of Milwaukee and Positron of Houston. GE earlier this year sought to sell its PET manufacturing capacity to Positron, but the deal fell through last month (SCAN 4/30/97). The latter company has been having liquidity problems.

There may be light at the end of the tunnel for Positron, however. Clinical studies have begun to show that PET can reduce hospital costs compared with SPECT, particularly in the cardiac area, said Howard Baker, Positron executive vice president.

"By using more accurate methods, you can eliminate unnecessary procedures. PET certainly does this, especially in the cardiac area," he said.

The Medicare reimbursement logjam for FDG could be ready to break, according to Coleman. Earlier this year, HCFA had Blue Cross and Blue Shield conduct a technical analysis of oncological PET imaging. They recommended reimbursement for PET in the indication of lung cancer.

"There is evidence from the best healthcare policy experts in the world to suggest that PET is helpful and cost-effective in managing patients with lung cancer. That is a large population," Coleman said.

The onset of coincidence gamma camera imaging may help standard PET's prospects in the reimbursement arena as well, Farmer said. When more nuclear medicine departments gain a stake in positron imaging, they will be inclined to lobby for regulatory relief.

Prospects for improving the supply of FDG and other PET radioisotopes could benefit as more coincidence technology comes on line, Douglass said. CTI is the main investor in P.E.T.Net Pharmaceutical Services, which is attempting to develop a broad network of commercial cyclotron distribution agreements to supply PET sites.

"We are positive about the coincidence option on gamma cameras," Douglass said. "Although it will be competition for PET, it will also allow us to proliferate the number of (FDG) distribution centers more quickly."

CTI is also likely to jump on the coincidence gamma camera bandwagon. In conjunction with Siemens, the firm is working on a camera using detectors made from LSO/YSO crystals that should provide both PET and SPECT imaging without compromising the performance of either, he said.

While multipurpose imaging systems may have an advantage in the average nuclear medicine department, there will likely be a niche for dedicated PET in the future, according to Farmer. PET cameras have a sensitivity edge over coincidence gamma camera technology. Since dedicated PET systems can acquire more counts, they can operate faster than gamma cameras.

"The two technologies are complementary," he said. "Over a period of time, as the adoption rate increases, certain centers will have sufficiently high volume where they can justify the financial costs of a PET system. In those places, it may make sense, based on patient volume studies, to have a PET system."