Is it FIT or FAM?

Multimodality fusion imaging dominates SNM show

The concept of fusion imaging is new enough that the industry has yet to sort out the acronyms, but this month’s Society of Nuclear Medicine show in St. Louis made it clear combined modalities are here to stay.

Of the hundreds of scientific papers presented at the conference, 41 dealt with some aspect of fusion imaging. Of these, 14 discussed the fusion of PET and MR, while 12 examined the uses of fused PET and CT.

The concept seems simple enough. Nuclear medicine’s strength is imaging disease processes with functional imaging from SPECT or PET, but its weakness is that it is often difficult to pin the images to underlying structures. With what Dr. Henry Wagner of Johns Hopkins University calls FIT, or fusion imaging tomography (and what GE Medical Systems calls FAM—functional anatomic mapping), nuclear images are coregistered with CT or MR.

A presentation by Dr. Bruce Sodee of University Hospitals of Cleveland showed a method of evaluating prostate cancer. A SPECT image alone could not define the extent of the tumor, but when it was superimposed on a CT scan into a single, rotating image, it became clear the disease had metastasized outside the prostate capsule. This could have significant implications for treatment.

“This is where we’re headed in nuclear medicine,” Wagner said. “By combining our findings with CT and MRI, anatomic structures (and the metabolic patterns of disease) can be displayed easily.”

There are only a handful of fusion products on the market, and most observers think it will be a year or two before vendors can gain FDA approval for combination machines and software. One issue is whether PET/CT or PET/MRI will dominate. The majority view seems to be that CT is more suitable in most cases.

“MRI brings a level of complexity to imaging that is not there with CT,” said Dr. Robert Carretta, the immediate past president of the society. “In diagnostic quality, we have to look at two issues—first cost, second throughput. The ultimate goal is to work out registration compatibility to imported CT or MRI images. Right now, it’s time-consuming and tedious and you have to worry about coregistration.”

Barbara Franciose, group vice president of nuclear medicine for Siemens, said that CT is the standard for morphology and PET is the standard for metabolic studies.

“Our CT rotates at the same speed as our PET, so there are a lot of things that make it cleaner and easier to do,” Franciose said. “If you look at a CT (scan), it’s bones. If you look at a PET (scan), it’s soft tissue, so they are complementary.”

“If we could register automatically, it would save time,” Carretta said. “The fact is, companies are willing to spend R&D dollars on fusion and attenuation correction,” he said.

Promising new technologies were part of the reason for a sense of optimism about the specialty at the meeting, according to Carretta. He said he had met with delegates from Japan, Korea, Italy, Germany, Australia, Canada, and Thailand.

“They were all upbeat and optimistic,” Carretta said.

Other SNM highlights:

Berlex, the U.S. subsidiary of drug giant Schering, was talking about its medical imaging products, but the big news was the company’s acquisition of CIS-US, which develops and sells medical radiopharmaceuticals and industrial radiography supplies. Berlex also recently acquired peptide imaging agent developer Diatide. The company has been known as a manufacturer of intravenous MRI contrast agents.

“We have been looking at the nuclear medicine field for 10 years,” said Berlex’s vice president and general manager for diagnostic imaging, Robert C. Milos. “We’ve had a growing research interest in (nuclear medicine). We were always interested in taking advantage of our fundamental resources, primarily the hundreds of millions of dollars we spend in cardiology and oncology. Basic biology can also be leveraged in the radiopharmaceutical area.”

Milos said Berlex believes in letting primary-care physicians know they can refer to nuclear medicine specialists.

“The referring physicians have to also know that they can request studies,” Milos said. “to a certain extent, that has been an Achilles heel to the people of this industry. We believe you need to get to the referring physician in order to make a lot of these products work commercially.”

GE Medical Systems showed its GE Millennium VG Hawkeye “FAM” fusion imaging system, which debuted at last November’s RSNA show, and which has received 510(k) approval from the FDA for SPECT/CT use. Carretta said his Sutter Roseville (CA) Medical Center is one of the locations that has been using the Hawkeye, which is still in clinical trials for PET/CT. During the examination, patients lie on a table that moves into a gantry where the CT is performed to acquire anatomical images. Immediately following, a SPECT or PET scan is performed to acquire functional images. Both are registered immediately for review on computer monitors. GE also announced the availability of a new nuclear medicine workstation to accompany the Hawkeye.

Mallinckrodt was pitching Leutech, an infection-imaging product it is developing with Palatin. The company’s ProstaSeed brachytherapy product, which came out in May, was also highlighted.

“The peptides are a long-term product for us, really linking our diagnostic capabilities to therapeutics,” said Michael R. Taylor, Mallinckrodt’s group marketing director for its nuclear medicine imaging group. “This is the first opportunity to highlight some of those peptide programs in a scientific study here.”

Positron showed off its recently introduced mPower PET scanner, designed to maximize patient throughput by providing a long field of view, which allows shorter patient scan times.

Siemens Medical Systems also announced plans to market a work-in-progress fusion PET/CT scanner, which it developed with CTI PET Systems, and which has been tested the past two years at the University of Pittsburgh Medical Center. Radiologists there have used the hybrid device to image a variety of tumors, including melanoma, lung, throat, and colorectal.

Toshiba and Siemens are working together on a number of products. Their collaboration started with the jointly developed E-Cam and now includes their new e.soft workstation. Toshiba also introduced its ART, or automatic registration tool, a software program to superimpose anatomical images from CT or MR studies on a nuclear medicine image. It works best in automatic mode for scans of images in such areas as the brain, where anatomical landmarks are well-defined, and can be operated manually.