Mansfield developed a mathematical technique that would allow NMR scans to take seconds rather than hours and produce clearer images than the technique Paul Lauterbur developed in 1973. Mansfield showed how gradients in the magnetic field could be mathematically analysed, which made it possible to develop a useful nuclear magnetic resonance imaging technique. Mansfield also showed how extremely fast imaging could be achievable. This became technically possible a decade later.

See also P Mansfield, "Multi-planar imaging formation using NMR spin echoes," J. Physics C. Solid State Phys. 10 (1977) L55–L58.

In 2003 Mansfield shared the Nobel Prize in Physiology or Medicine with Paul Lauterbur "for their discoveries concerning magnetic resonance imaging." See No. 2700.5.