Obituary: Professor Sir Peter Mansfield, whose invention of the MRI scanner revolutionised medicine

Sir Peter Mansfield - even better than a rocket scientist. University of Nottingham

Peter Mansfield, who has died aged 83, was born and raised in Lambeth and Southwark, south London, and left school at 15 without formal qualifications to work as a printer’s apprentice. Yet in an illustrious 40-year career he was awarded a Nobel prize for medicine for his pioneering work on magnetic resonance imaging, was elected a Fellow of the Royal Society, and was knighted for his services to science.

As a child, Mansfield lived through the blitz, but far from finding this a frightening experience he was fascinated by V1 rockets and made up his mind to become a rocket scientist. He wrote to the editor of the Daily Mirror (his family’s paper) asking how he could get such a job and was told to write to the Ministry of Supply. And so, amazingly, he found employment at the Rocket Propulsion Department in Westcott, Buckinghamshire. Evening classes to take A-levels secured him a place at Queen Mary University London (then Queen Mary College), where he studied physics.

Sir Peter Mansfield’s development of MRI changed medicine. University of Nottingham, Author provided

His first encounter with nuclear magnetic resonance (NMR), then a technique used primarily for chemical analysis, was in his undergraduate project, making use of the newly invented electronic transistor to build a proton magnetometer. This he put to use as a metal detector to look for hidden artefacts in the car park.

His first important scientific contributions were in the field of solid state NMR, where he astounded the NMR research community by demonstrating that an NMR signal thought to be lost could be recovered and used. At the University of Nottingham, where he took up a lectureship in 1964 and spent the rest of his professional career, Mansfield used NMR to determine the structure of crystals, and realised that the gradients of magnetic fields were key. While they weren’t strong enough to create images at the atomic resolution required for examining crystals, they were perfect for biological structures. NMR imaging, later re-named magnetic resonance imaging (MRI), was born from this realisation.

Thus far MRI had only been demonstrated in test-tube sized samples – the finger of a research student, in fact – and many thought it could not be scaled up. But within two years, Mansfield himself became the first person to be scanned in a prototype MRI machine. Though MRI is now considered to be a completely safe technology, documents that circulated through the labs at the time contemplating human imaging suggested otherwise – there was even speculation it could cause an instant heart attack. And so before his scan Mansfield ensured he had updated his will and his wife Jean insisted she be present. That scan of his abdomen took some tens of minutes to acquire. Of course he survived, but he wasn’t satisfied: he wanted to make images of dynamic processes such as a beating heart.

Sir Peter Mansfield at an MRI scanner with Margaret Thatcher and Sir Colin Campbell. University of Nottingham, Author provided

While wrestling with this problem the revelation as to how to achieve the required increase in speed came to him while waiting at a red traffic light on his way home for lunch – he often felt insight comes when one’s attention is temporarily elsewhere. Echo-planar imaging (EPI) made it possible to produce 100 images per second, fast enough to “freeze” cardiac motion. However, it was technically challenging and would not be offered in commercial systems for another decade or more. Again, it was Mansfield’s own characteristic dogged determination to solve a problem coupled with a brilliant mind that saw him provide the solution that made it possible.

Above all Mansfield saw himself as an inventor: his many patents are essentially the history of the development of MRI. He continued to develop his echo-planar imaging technique, and his classic demonstration of generating real-time cross-section images of a body moving through the scanner will be remembered by many a visitor to his lab.

The development of MRI revolutionised diagnostic medicine by revealing for the first time images of the internal structure of the body’s soft tissues and organs in exquisite detail. EPI opened the door to see dynamic processes of a living body and functional MRI, which builds upon EPI, is today beginning to unlock the secrets of the human mind by revealing which parts of the brain are active during certain mental states.

FMRI scan during working memory tasks. John Graner

With the encouragement of his family, Mansfield dedicated himself to lifelong development of MRI. But he retained his interest in flight, offering as an undergraduate project the development of a man-powered helicopter. Sadly, ill health curtailed his own flying ambitions.

Peter Mansfield was knighted in 1993 and retired from the University of Nottingham in 1994, but continued working as an emeritus professor. His work on MRI was recognised in 2003 with the Nobel Prize for Physiology or Medicine, shared with Professor Paul Lauterbur. His first MRI scanner is on display at the London Science Museum and his portrait hangs in the National Portrait Gallery.

While he didn’t have the career as a rocket scientist he craved, his contribution to humanity has been immense. Born 1933, Professor Sir Peter Mansfield passed away on February 8, 2017, aged 83. He is survived by his wife Lady Mansfield, and his two daughters Gillian and Sarah.