Ravi Menon, PhD

Canada Research Chair, Functional Magnetic Resonance Imaging Professor, Schulich School of Medicine & Dentistry: Director, Centre for Functional and Metabolic Mapping
Researcher of the month: 
Mar 2016

Working with “The Magnet”

“The magnet”, as Dr. Ravi Menon fondly calls the magnetic resonance imager (MRI), is like a car. Models range from a 1.5 Tesla (1.5T) subcompact to the powerful 7T Ferrari. Most MRIs in clinical practice in Canada are 1.5T, mid-size, family cars.

Menon drives a Ferrari. His laboratory at the Robarts Research Institute (RRI), University of Western Ontario, has the only ultra-high field (7T) human MRI in Canada.

What’s the difference? Older 1.5T machines have the resolution of 1950s televisions, compared to today’s ultra-HDTVs. So, when Menon and his team of neuroscience researchers take a close look at the brain, they see more detail than ever before.

“Many changes that occur in neurological diseases are visible when you have the ability to resolve at 0.5 mm, which you can do at 7T. MRI in routine practice resolves at about 1.5 mm. That doesn’t sound like a big deal, but it’s actually an enormous difference,” he explains.

The cortical mantle around the brain is about 2-mm thick, says Menon, Professor, Schulich School of Medicine & Dentistry, and Canada Research Chair and Director of the Centre of Functional and Metabolic Mapping at the RRI. In 1.5T MRIs, the mantle looks like one big, blurry blob.

“At 7T, you see layers. You can identify things that go wrong in those layers. It’s a nice ‘sweet spot’ for a diagnostic tool.”

He and his research team use structural and functional MRI to study how the normal brain works and what goes wrong in patients with neurological diseases, such as multiple sclerosis (MS), cerebral palsy, epilepsy, and Alzheimer’s disease.

For example, people who exhibit early MS symptoms are often sent home after a single clinical episode without a diagnosis. Because a second episode may not happen for months or years, they must live in a diagnostic limbo. Menon and his colleagues have shown that, during this gap in clinical care, MS causes abnormal changes that further brain damage.

“By the time people receive a diagnosis of MS, they’re not in the most effective place to stop progression of the disease,” he says. For that reason, he and his team are working to devise ways to use MRI to detect MS definitely at its earliest stages.

“Some people with MS manage quite well, but others are on a bad trajectory. Treatment depends on prognosis,” he adds. “We would like to identify who is on which trajectory as soon as possible.”

To that end, he and his team are searching for MRI biomarkers to tip off clinicians about the prognosis of patients with MS. 

A pioneer of fMRI

Menon has pioneered key advances in brain imaging research and helped to perfect MRI technology.

He has worked on one of two teams worldwide that first used functional magnetic resonance imaging (fMRI) in humans and, at his laboratory, continues to develop and champion the use of ultra-high field MRI as a top-notch diagnostic and investigative tool – ever advancing the field of diagnostic imaging.

He is one of only six Canadians to become a senior fellow of the International Society for Magnetic Resonance in Medicine (ISMRM).

In the early 1990s, he worked in Kamil Ugurbil’s laboratory at the University of Minnesota. The laboratory was small, employing five or six people and, as the only post-doctoral fellow, Menon was assigned to the project.

A discovery like fMRI happens only once in your career, he concedes. “It’s hard to explain how exciting it is and what a confluence of events it takes for something like that to actually happen.”

He and a handful of colleagues worked 18- to 20-hour days for “a couple of years” in a race to obtain viable fMRI results. “It was something so revolutionary that you wanted to be the first to do it.”

There were many setbacks due to technological instability. The research team had a lot of ‘oh crap’ moments, “yet I recall very clearly the night when we did the first experiment that worked definitely.”

That experiment set out to prove that you could localize brain function by exposing it to particular stimuli. The team used LED lights on ‘the magnet’ to activate the brain’s visual cortex, then scanned that brain activity with fMRI. 

“It was the first unequivocal demonstration that fMRI worked. I still pinch myself,” he says, “because it’s hard to believe, even after 26 years, that you can actually look at brain function with a non-invasive technology on a sub-millimeter scale. It’s super cool that fMRI is now part and parcel of normal, everyday medicine.”