A device developed by a collaborative team of researchers could turn PET imaging on its head.
The term pet helmet may evoke images of a cat or dog wearing cute headgear to protect them from getting knocked in the head. But the AM-PET helmet, an acronym for Ambulatory Microdose Positron Emission Tomography, does much more. It’s the first mobile and wearable molecular brain imager that enables relatively free movement of a person's head and upper body.
While not likely to win any style awards, it could turn PET imaging on its head. That’s because no one has ever imaged the human brain with both high sensitivity and high resolution in an upright, moving subject. The device was developed by a collaborative team of researchers from West Virginia University (WVU), the University of California, Davis, the University of Virginia, University of Washington, and GE Global Research.
“We wanted to look at metabolic and cellular processes of the brain while upright people did normal things,” says lead researcher Julie Brefczynski-Lewis, assistant professor in the WVU School of Medicine Department of Physiology and Pharmacology.
Walk This Way
Unlike current brain imaging devices, the AM-PET doesn’t require the patient to be immobile, seated or prone, with very little movement allowed. “That’s contrary to what we humans do in our daily lives—we move around,” she said. “We also want to accommodate someone who can’t stay still or maybe can’t follow directions.”
The wearable’s 12 small camera-sized sensory detectors are much smaller than those on a standard PET. They can be placed close to the head, allowing for high sensitivity. The team intends to build models accommodating heads of different shapes and sizes, while still ensuring a close fit, said Thorsten Wuest, assistant professor of smart manufacturing at WVU.
“Ideally, the helmet must be fitted tightly to reduce the relative movement of head to system, without being uncomfortable for the patient wearing it,” he said. “It does look simple, but in reality, all of these considerations make the project complex—yet exciting from an engineering perspective.”
Robot or Not
In a perfect world, the device would be “essentially weightless,” but its current iteration is not, Brefczynski-Lewis said. It weighs 6 pounds, which is a lot for a person to carry on their head. “The final version of this device may weigh between 6 to 10 pounds. We eventually want to cover whole brain with another device and that could weigh up to 20 pounds.” As a result, Wuest designed and built in a weighted pulley system to take the pressure off a subject's head and neck.
The researchers have also proposed a backpack version. "For now, there’s the issue of improving the system itself, with cables and software solutions still under development, Wuest said. “It’s difficult to finalize defined specs, and when you try to implement them in the design, they may change during this process of constant adaptation.”
Wuest said the team is also entertaining thoughts of a robotic solution. “Exoskeleton research projects are underway and it would be interesting to explore with experts who have that pertinent experience,” he said.
Early Detection
“The message from me, the inventor, is clear: I want this device to help with brain diseases,” said Stanislaw (Stan) Majewski, visiting professor of radiology and medical imaging at the University of Virginia.
Majewski’s 2011 patent applies to the AM-PET invention, submitted in 2008 before he joined West Virginia University and met Brefczynski-Lewis.
Approximately 10 years ago, Majewski got the AM-PET helmet idea at the Brookhaven National Laboratory in New York by watching rodents with tiny metal PET imagers called RatCaps on their heads.
"The compact, ring-like PET imager enables very high-resolution imaging of neurological brain functions, cancer, and effects of trauma using a rather simple mobile scanner with limited space needs for use and storage," he said. It works by imaging the distribution in the brain of radioactive fluorodeoxyglucose that’s been injected into the body.
“We hypothesize that doses as low as 1 to 10 percent of the standard injection dose will become possible when imaging with whole body PET-CT scanners, without adversely impacting the task-specific accuracy of imaging procedures,” Brefczynski-Lewis said.
Multiple Uses Possible
The project is funded by a $1.5 million grant from the National Institutes of Health, specifically the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, a public-private effort established in 2013 by the Obama administration.
The AMPET team proposes using the helmet for a variety of diagnostic uses, such as with epilepsy, stroke, Alzheimer’s, brain surgery with ultrasound, and glioblastoma, the most aggressive cancer of the brain. It may also prove valuable for tracking brain responses to rehabilitation or drug treatments.
“We also want to use it for dementia, [mild traumatic brain injury] and PTSD, where it can have the highest impact,” Majewski said. “It is my dream to do something for our veterans. I really feel that as a society we owe them so much.”
Stephanie Stephens produces health content in Orange County, California.