Siemens tweaks PET/CT T with hybrid for radiology

Siemens Healthcare wants to move PET/CT into the radiology department. The German multimodality vendor, a pioneer in PET and an innovator in CT technology, plans to accomplish this with a hybrid scanner that integrates off-the-shelf components from these two modalities into a spectrum of possibilities united by design and marketing elements oriented toward radiologists.

The focal point of this corporate strategy is the Biograph mCT (molecular CT). Positron imaging takes a supporting role to the newly minted star, "smart contrast," which relies on PET radiopharmaceuticals to enhance the morphological and dynamic information delivered by CT.

Toward this end, the Biograph mCT can be equipped with a high-performance CT generating up to 128 slices. Miniaturization and component integration enhance patient comfort by reducing the tunnel to just a meter long, about two-thirds the size of conventional PET/CTs, and widening the bore CTs, and widening the bore to 78 cm.

"This is very much a radiological device," said David W. Townsend, Ph.D., director of the molecular imaging and translational research program at the University of Tennessee in Knoxville. "It is very much a CT-oriented device with a molecular component."

Townsend pioneered PET/CT with his development of the first such hybrid prototype in 1998 at the University of Pittsburgh. He has since joined the University of Tennessee and serves as a Siemens luminary, having contributed to the early development of the Biograph mCT.

This compact, stylized version of PET/CT reflects a major change at Siemens, which is trying to rejuvenate fading demand in the U.S. for PET/CT by extending its appeal from just nuclear medicine departments to radiology. This change in strategy is reflected in the rebranding of positron imaging as molecular CT.

"We don't call it PET/CT because we are approaching it this time from the other side," said Markus Lusser, vice president of global marketing at Siemens Molecular Imaging.

The new system is weighted toward CT. The company is positioning the Biograph mCT as a two-in-one special that keeps capital equipment, operator, and life-cycle costs in check and conserves space. The pitch is that customers can save money buying the mCT over purchasing a CT and a PET/CT separately."

If you buy a PET/CT and also buy a CT scanner, maybe both are utilized at just 60% capacity," Townsend said. "Why not buy a molecular CT to serve both patient populations? You have one room, one device, and one service contract."

Introduced in mid-October at the annual meeting of the European Association of Nuclear Medicine, the Biograph mCT is slated to appear on the RSNA exhibit floor later this month. The company expects to begin routine shipping of the new product in the first quarter of 2009.

The system can be configured to deliver up to 128 CT slices per 300-msec rotation and perform five-minute PET scans. The Biograph mCT can combine advanced technology found in the Siemens Somatom Definition AS (Adaptive Spiral) with Siemens' PET technology. Rapid CT and PET scans reduce the risk of patient motion and, consequently, the appearance of artifacts in the images. Such rapid scans also improve patient comfort.

But customers need not purchase a system at such a premium level of performance. They can custom order the mCT to meet specific needs, according to Lusser. The CT component can support 40, 64, or 128 slices. The positron imaging components can be arranged to allow anything from entry-level to the most advanced PET imaging, including time-of-flight studies. And if clinical requirements change in the future, the Biograph mCT can be upgraded to deliver more slices and higher defi-nition PET, according to Lusser.

The clinical value of the system, therefore, will be defined by individual purchaser. All the oncology applications that have come to characterize PET/CT over the past seven years" as this combination of modalities is used to delineate lesions in the diagnosis, staging, and restaging of cancer"are available.

The advanced capabilities conferred by CT may take PET/CT into new applications as well, made possible by superimposing blood flow over PET and CT-based images of tumors. This could affect surgical and radiation therapy planning, Townsend said. The superfast rotation time and available high number of slices per rotation open opportunities in cardiology as well.

The Biograph mCT represents the next phase in PET/CT, according to Townsend, who a decade ago envisioned this hybridization as "a clinical CT with a clinical PET."

Its adoption for oncological purposes has led to an underutilization of the CT component, he said. The mCT promises to correct this. If it does, the change will be a testament as much to packaging and market positioning as to engineering. The device's components offer no new clinical capabilities. Rather, their integration is designed to open a new segment of the imaging marketplace to the purchase of PET/CT, a segment populated by radiologists.