New 3D body scanner uses 40 times less radiation than PET scans

An unbelievably clear look at what goes on inside our bodies.

  • New medical imager captures unprecedented 3D images of the human body.
  • It's 40 times faster than PET scans, and can use 40 times less radiation.
  • EXPLORER scanner makes PET and CT scans look old-fashioned.

What do you get if you combine the technologies on which the two most successful medical imaging devices — positron emission tomography (PET) and x-ray computed tomography (CT) — are based? You get EXPLORER, the stunning new scanner that can capture an amazingly detailed 3D image of the entire human body in 20–30 seconds.

EXPLORER's super-fast capture rate — it can scan a body region in about a second — also allows it to take movies of specially-tagged medications and radiotracers as they make their way through a body.

The development of EXPLORER

(UC Davis)

EXPLORER was developed at the UC Davis Department of Biomedical Engineering by biomedical engineers Simon Cherry and Ramsey Badawi in partnership with Shanghai-based United Imaging Healthcare (UIH). UIH plans eventually to manufacture and sell the devices worldwide.

Badawi and Cherry first conceived of something like EXPLORER some 13 years ago. In 2011, a $1.5 million grant from the National Cancer Institute allowed them to pull together a consortium of collaborators to work on the idea. The first working EXPLORER was made possible by a $15.5 million grant from the National Institutes of Health in 2015.

First look

The first images Badawi got his eyes on were captured by UIH and the Department of Nuclear Medicine at the Zhongshan Hospital in Shanghai, and they were eye-popping. As he told UC Davis Health:

The level of detail was astonishing, especially once we got the reconstruction method a bit more optimized. We could see features that you just don't see on regular PET scans. . . And the dynamic sequence showing the radiotracer moving around the body in three dimensions over time was, frankly, mind-blowing. There is no other device that can obtain data like this in humans, so this is truly novel.

Benefits of EXPLORER

(UC Davis)

EXPLORER is 40 times as fast as a PET scanner, making it more feasible to do repeated studies on an individual, and, of course, there are the movies that can provide an unprecedented look at the in-body progress of radiotraceable agents. EXPLORER'S also 40 times more sensitive than PET scanners, so it will cause patients to be exposed to far less radiation during diagnosis than traditional PET or CT scans.

"The tradeoff between image quality, acquisition time and injected radiation dose will vary for different applications," Cherry told UC Davis Health. "But in all cases, we can scan better, faster or with less radiation dose, or some combination of these."

Doctors will also be able to see, for the first time, what's happening simultaneously in multiple areas of the body, helping them measure dynamic processes such as bloodflow or glucose takeup. The uses for EXPLORER's breakthrough technology seem endless.

The goal right now is to get the first working system up and running at the EXPLORER Imaging Center in Sacramento by June 2019. At that time, the scientists hope to begin using EXPLORER for research projects and for diagnosing patients. Meanwhile, at Zhongshan Hospital, investigation of EXPLORER's potential continues.

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Yale scientists restore brain function to 32 clinically dead pigs

Researchers hope the technology will further our understanding of the brain, but lawmakers may not be ready for the ethical challenges.

Still from John Stephenson's 1999 rendition of Animal Farm.
Surprising Science
  • Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
  • They hope the technology will advance our understanding of the brain, potentially developing new treatments for debilitating diseases and disorders.
  • The research raises many ethical questions and puts to the test our current understanding of death.

The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?

But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.

What's dead may never die, it seems

The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.

BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.

The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.

As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.

The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.

"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.

An ethical gray matter

Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.

The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.

Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.

Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?

"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."

One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.

The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.

"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.

It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.

Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?

The dilemma is unprecedented.

Setting new boundaries

Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."

She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.

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