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."

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