PET/MR Same-Time Scanner: Less Radiation, Clearer Images

For the past several years, the industry has been moving toward more hybrid imaging. For some facilities and practices, that means using a PET/MR combination machine, most of which take sequential images. But what if you could take those images at the same time and with less radiation? There’s now new technology on the horizon.

A development from Norway could allow you to not only obtain PET and MRI images simultaneously, but it could drastically reduce the radiation risk to your patients. Particle physicists from the University of Oslo have designed a PET scanner small enough to fit inside an MRI machine. Currently, this dual machine is only available for preclinical cancer scanning with animals, but researchers plan to build a version acceptable for hospital use.

“Our PET design is highly sensitive, meaning it reduces radiation dose to the animals being examined,” said Erlend Bolle, a particle physics researcher in the University of Oslo (UiO) physics department in a written statement. “The amount of reduction depends on the design, but in the best case scenario, we could achieve up to a 100 percent increase in sensitivity compared to some of the best scanners on the market. That would allow us to acquire data needed for image reconstruction in half the time.”

With a traditional PET scan, cancerous cells are identified by the radioactive isotopes collected when cells absorb sugar molecules. To achieve better images with reduced radiation, the researchers developed a 3-D , five-layer detector made of crystals and light guides. The detectors, Bolle said, capture more photons, doubling the PET scan sensitivity and halving the radiation dose.

Transitioning this technology to the patient-care environment only requires scale-up, he said. The detectors, read-out electronics, triggering system, and software were all constructed with a hospital-focused scale-up in mind. The detector module can also be redesigned to better fit a large ring geometry.

And, as cost-cutting and resource-conservation initiatives from health care reform begin to take effect, combination machines will become integral to the future of diagnostic imaging, said Robert Brait, Siemens Healthcare product manager.

“It’s important to have hybrid imaging because hospitals will need their space for patient beds more than they’ll need six rooms for six separate CT scanners and three more for PET or MRI machines,” he said. “With one device to do multiple things, hospitals have more efficient use of space and better utilization of resources.”

As its hybrid imaging solution, Siemens offers the Biograph mMR. This 3T MRI machine also offers simultaneous PET and molecular MR imaging. The scan provides a look at the ongoing physiology taking place in a specific area of the body and maps it against the anatomical image procured through the MRI.

Philips also offers new PET/MR equipment, called the Ingenuity TF PET/MR. Much like Siemens’ Biograph, the Ingenuity is also a 3T machine, but it offers sequential scanning. It is equipped with Time-of-Flight PET scanning technology that measures the time between photon events in the attempt to improve image resolution.

However, neither PET/MR machines from Siemens or Philips offer the level of radiation reduction projected in the Oslo technology.

Being able to obtain higher quality images that highlight both the structure and function of certain cells within the body isn’t only a technological advantage, Brait said. It’s also an improvement that will positively impact the speed and quality of patient care.

“The PET/MR combination allows you to use biomarkers that are more developed toward the illustration of specific diseases. With MR being a soft tissue imaging modality, there’s huge value there because there are far more soft-tissue lesions than bone lesions,” he said. “Innovative biomarkers to image disease processes may help to better quantify and diagnose the different types of disease.”

Ultimately, Brait said, perfecting a PET/MR machine that uses less radiation and takes up less space with animals will create a smoother path for the continued growth of bench-to-beside research.

“This development from the Oslo researchers is good news,” he said. “It will be key to preclinical scanning that leads to translational medicine, moving health care from mouse to man.”