Medstars’ Heroes: Sir Peter Mansfield | MRI Scanner

Forty two years ago the face of diagnostic medicine changed forever. The invention of the magnetic resonance imaging (MRI) scanner has and continues to save and improve the quality of millions of lives. It’s development revealed internal human anatomy with astonishing precision and without the risks carried by radiation. Nobel prize winner, Sir Peter Mansfield, was its inventor and principal architect.

Early beginnings 

Sir Peter was born in 1933, Lambeth, South London. His career in education didn’t start too brightly. He took the 11 plus exam at primary school and wasn’t successful. Although he didn’t pass the exam, Peter showed impressive qualities in woodwork and metalwork. His proceeding education had been halted by the Blitz, forcing Peter to leave London as an evacuee aged 15. He left school with no qualifications and soon came face-to-face with the school’s careers officer. The careers officer questioned his future and was rather taken aback when Peter said that he wanted to be a scientist. Peter had an intense interest in science that spawned from a fascination of rockets and rocketry. He enjoyed learning about them from regular visits to the science museum in South Kensington. The careers officer told him to ‘get sensible’ and thus began Peter’s first profession as a printer.


Rather than let his career officer’s words limit his future aspirations, Peter used the advice as a catalyst to get the qualifications he needed to fulfil his dream. His first step was to head out at 15 years of age and take evening classes – immediately. He began classes five nights a week at Borough Polytechnic (now London South Bank University). Five nights a week meant five topics to study; Peter chose mathematics, physics, chemistry, English and French. During this time, Peter continued working as a printer. For three years he spent his days working and his evenings studying.

One day, Peter stumbled across an article in the children’s section of the Daily Mirror about a grammar school boy who had decided he wanted to be a rocketeer. After reading about the endeavours of the boy, Peter wrote to the editor of the Daily Mirror asking how he could find a job in rocket science. The reply pointed him in the direction of the Rocket Propulsion Department (RPD) in Westcott. Peter impressed at an interview for the establishment with his self-taught knowledge of rocket science and burning desire to learn more. He was told to continue his studies and achieve his qualifications, but could work with them as a science assistant in the meantime.


Peter achieved the equivalent of 3 A-Levels in pure maths, applied maths and physics at Queen Mary University, London. He graduated university with first-class honours and continued studying for a PhD. For his PhD, Peter was offered a place in a team building a nuclear magnetic resonance (NMR) system for detecting underground objects – he gratefully accepted. Peter finished his studies at Queen Mary, but maintained his interest in NMR. He married Jean Kibble in 1962 and, after two years at the University of Illinois, was appointed lecturer of physics at the University of Nottingham. It was here that Peter’s true brilliance came to fruition.


Whilst working with his team at the University of Nottingham, Peter began to develop the MRI scanner.

Peter theorised that images could be generated of the inside of the human body through the use of magnets and radiofrequencies. As the human body is made of roughly 70% water, the magnetic properties of hydrogen atoms found inside, when put through a magnetic field, will have two possible states: parallel and opposed. A radiofrequency accurately tuned to the difference in energy between the two states would result in a transition or resonance. Peter identified that in a magnetic gradient the resonance frequency would correspond to position, thus producing an image.

At this point in time, computed tomography (CT or CAT) scans were the most popular means of viewing the inside of the human body in this way. However, CT scans use ionised radiation for imaging which must be treated with caution if repeated on one person multiple times. The MRI can, not only be used safely as many times as necessary, but can also be used on pregnant women.


The theory was in place and Sir Peter and his team began preparing for tests. In 1976, the apparatus available for testing was very small, but seemed to work as an early prototype. For human demonstration, the tip of a finger from one of Peter’s PhD students was placed into the scanner and, as expected, an inside image was generated. The next step, of course, was to test the system on a whole human body. And who better to step inside the first ever full-body MRI scanner than Peter Mansfield himself.

The machine was incredibly narrow allowing for minimal movement, if any at all. The room held its breath as the system booted up with Peter inside. To everyone’s delight the machine worked and, to top it off, returned a perfectly healthy Peter Mansfield as well. After the success of the scan, Peter was quoted as nonchalantly saying, “the worst thing that could’ve happened would’ve been cardiac arrest.”


Peter was elected fellow of the Royal Society in 1987 and was awarded its Wellcome and Mullard medals in 1984 and 1993, respectively. He was knighted in 1993 and shared the 2003 Nobel Prize for Physiology or Medicine with Paul Lauterbur, who had been working simultaneous on MRI in America. Peter’s department at the University of Nottingham lives on today as the Sir Peter Mansfield Imaging Centre.