Novel Add-On to Small-Animal Imaging Technology Improves Resolution

The dual-function imaging system gives biomedical researchers two main advantages: lower cost and the ability to use a broad range of radiopharmaceuticals, or tracers, associated with both platforms.

Tracers are substances that allow researchers to visualize metabolic processes so they can follow disease progression or the effects of potential therapies.

For manufacturers of imaging systems, the technology presents a new way of constructing PET and SPECT dual-function imagers.

“It is highly desirable to have access to both PET and SPECT modalities on an integrated platform, so that the most effective radiopharmaceutical can be used to investigate the biological target under study,” says Yao. 

Yet, current costs are “prohibitively high for most potential users,” he adds.

Yao’s team estimates its dual system would cost 40 percent less than the available juxtaposed or combined standalone systems.

These cost savings are achieved “by sharing the detector and electronic hardware between the PET and SPECT imaging modes,” Yao explains.

The team’s SPECT add-on device, inserted inside a PET scanner, integrates a rotatable collimator made of a tungsten cylinder with opening apertures such as pinholes or slits.

Over the past seven years, Yao’s group has published seven papers in peer-reviewed journals describing their innovative technology and methods.

The researchers have developed add-on SPECT imaging on two different animal PET scanners, and have implemented different system designs tailored for imaging rats and mice.

“Nominal phantom and live animal studies show that both add-on SPECT systems achieve expected image resolution and sensitivity,” Yao says.

A recent study involved developing and testing a faster, easier method to callibrate the add-on unit, characterizing its geometrical parameters—a necessary step to achieve high-quality images.

The researchers derived these measures directly from PET images by first marking sections of the collimator’s pinholes with a positron-emitting radioactive solution. PET imaging of the collimator was then performed at multiple rotational positions, thus defining the system matrix.

The researchers found this method to be “highly effective.”

The resulting paper, “PET-Based Geometrical Calibration of a Pinhole SPECT Add-On for an Animal PET Scanner,” has been published in Physics in Medicine and Biology by the Institute of Physics (IOP), and featured on the IOPscience website. The study also was covered by medicalphysicsweb.

First author Xiao Deng, PhD, previously a visiting research fellow at UB, is now a postdoctoral researcher at Rush University Medical Center in Chicago.

Yao’s group received a 2010 pilot grant for novel clinical and translational methodologies from the UB Clinical and Translational Science Institute.

The UB group and collaborators at the University of Sherbrooke in Quebec, Canada, and Tsinghua University in China, are now seeking ways to commercialize their add-on SPECT technology.