Nav: Home

Mini 'magic' MRI scanner could diagnose knee injuries more accurately

June 28, 2019

Researchers at Imperial College London have developed a prototype mini MRI scanner that fits around a patient's leg.

The team say the device - which uses so-called 'magic angle' effect - could potentially help diagnose knee injuries more quickly, and more accurately.

In a proof-of-concept study using animal knees, the results suggest the technology could be used to show all the structures of the knee.

The scientists say the device (which looks like a large metal ring through which a patient places their leg) could help diagnose conditions such as anterior cruciate ligament injuries - particularly common among footballers.

Furthermore, the small size of the device could enable it to be used in local clinics and even GP surgeries, potentially reducing NHS waiting times for MRI scans.

The research was funded by the National Institute for Health Research.

Currently, key components of the knee joints such as ligaments and tendons are difficult to see in detail in the MRI scans, explains Dr Karyn Chappell, a researcher and radiographer from Imperial's MSK Lab: "Knee injuries affect millions of people - and MRI scans are crucial to diagnosing the problem, leading to quick and effective treatment. However we currently face two problems: connective tissue in the knee is unclear on MRI scans, and people are waiting a long time for a scan."

Dr Chappell added: "This can cause particular problems for women, as they are at greater risk of anterior cruciate ligament injuries. The reasons for this are unclear, but it could be linked to hormones such as oestrogen making ligaments more elastic, leading to more joint injuries."

Knee injuries commonly affect one of three areas: the tendons (which attach muscle to bone), the meniscus (a cushioning pad of cartilage that prevents the bones of the joints rubbing together), or the ligaments (tough bands of connective tissue that hold bones in a joint together).

Following knee injury a doctor may refer a patient for a MRI scan to help establish which part of the joint is injured. MRI scans use a combination of radio waves and strong magnets to 'flip' water molecules in the body. The water molecules send out a signal, which creates an image.

However, tendons, ligaments and meniscus are not usually visible with MRI, due to the way water molecules are arranged in these structures, explains Dr Karyn Chappell.

"These structures are normally black on an MRI scan - they simply don't produce much signal that can be detected by the machine to create the image. This is because they are made mostly of the protein collagen, arranged as fibres. The collagen fibres hold water molecules in a tight configuration, and it is in fact water that is detected by the MRI. If you do see a signal it suggests there is more fluid in the area - which suggests damage, but it is very difficult for medical staff to conclusively say if there is injury."

To overcome this problem, Dr Chappell harnessed the power of a phenomenon called the 'magic angle': "The brightness of these tissues such as tendons and ligaments in MRI images strongly depends on the angle between the collagen fibres and the magnetic field of the scanner. If this angle is 55 degrees the image can be very bright, but for other angles it is usually very dark."

The team explain the magic angle is achieved in their scanner because they are able to easily change the orientation of the magnetic field. While the patient sits comfortably in a chair, the specially designed magnet (which uses motors and sensors similar to those found in robots in car factories) can rotate around the leg and the orientate magnetic field in multiple directions.

This is not possible in current hospital MRI scanners, which are also much more expensive than the prototype scanner.

"Previously the magic angle phenomenon was thought of as a problem, as it could mean medical staff mistakenly thinking the knee is injured. However, I realised that if we took a number of scans around the knee, we could use the signal produced by the magic angle effect to build a clear picture of the knee structures," explained Dr Chappell.

"Specifically, we can combine images obtained at different magnet angles and not only increase the brightness, but also see how the collagen fibres are arranged. This enables us to establish the pattern of collagen fibres in the knee structures, which is crucial information ahead of treatments such as repairing a torn meniscus," added Dr Chappell.

"At the moment, it's very difficult to see which direction the collagen fibres run in a meniscus. This is important because sewing across the fibres will effectively repair a tear in the meniscus. However if the stitch is in the same direction as the fibres, the repair may fail."

In a new study, published in the journal Magnetic Resonance in Medicine, the multi-disciplinary team scanned the knee joints of six goats and ten dogs in a conventional MRI scanner.

All of the dog legs were donated by the Royal Veterinary College, having been donated for research by dog owners following the death of their pet.

Dogs suffer from knee injuries and arthritis similar to humans, making them a good subject for the study.

The results showed that using the magic angle can accurately detect ligament and tendon damage.

The team say now they know magic angle scanning can be used to visualise the knee, combining this with the new prototype mini scanner could enable knees to be accurately scanned with this technology - and hope to progress to human trials of the 'mini' scanner within a year.

Dr Chappell explained: "Although this is an early-stage proof-of-concept study, it shows the technology could potentially be used to accurately detect knee injury. We now hope to enter human trials - and explore if this technology could be used for other joints such as ankles, wrists and elbows."
-end-


Imperial College London

Related Magnetic Field Articles:

Origins of Earth's magnetic field remain a mystery
The existence of a magnetic field beyond 3.5 billion years ago is still up for debate.
New research provides evidence of strong early magnetic field around Earth
New research from the University of Rochester provides evidence that the magnetic field that first formed around Earth was even stronger than scientists previously believed.
Massive photons in an artificial magnetic field
An international research collaboration from Poland, the UK and Russia has created a two-dimensional system -- a thin optical cavity filled with liquid crystal -- in which they trapped photons.
Adhesive which debonds in magnetic field could reduce landfill waste
Researchers at the University of Sussex have developed a glue which can unstick when placed in a magnetic field, meaning products otherwise destined for landfill, could now be dismantled and recycled at the end of their life.
Earth's last magnetic field reversal took far longer than once thought
Every several hundred thousand years or so, Earth's magnetic field dramatically shifts and reverses its polarity.
A new rare metals alloy can change shape in the magnetic field
Scientists developed multifunctional metal alloys that emit and absorb heat at the same time and change their size and volume under the influence of a magnetic field.
Physicists studied the influence of magnetic field on thin film structures
A team of scientists from Immanuel Kant Baltic Federal University together with their colleagues from Russia, Japan, and Australia studied the influence of inhomogeneity of magnetic field applied during the fabrication process of thin-film structures made from nickel-iron and iridium-manganese alloys, on their properties.
'Magnetic topological insulator' makes its own magnetic field
A team of U.S. and Korean physicists has found the first evidence of a two-dimensional material that can become a magnetic topological insulator even when it is not placed in a magnetic field.
Scientists develop a new way to remotely measure Earth's magnetic field
By zapping a layer of meteor residue in the atmosphere with ground-based lasers, scientists in the US, Canada and Europe get a new view of Earth's magnetic field.
Magnetic field milestone
Physicists from the Institute for Solid State Physics at the University of Tokyo have generated the strongest controllable magnetic field ever produced.
More Magnetic Field News and Magnetic Field Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.