Interestingly, Dr Isidor Rabi, an American physicist who was awarded the Nobel Prize for Physics in 1944 for his invention of the atomic and molecular beam magnetic resonance method of observing atomic spectra, came across the NMR experiment in the late 1930's but considered it to be an artefact of his apparatus and disregarded its importance. During the 50's and 60's NMR spectroscopy became a widely used technique for the non-destructive analysis of small samples. Many of its applications were at the microscopic level using small (a few centimetres) bore high field magnets. In the late 60's and early 70's Raymond Damadian, an American medical doctor at the State University of New York in Brooklyn, demonstrated that a NMR tissue parameter (termed T1 relaxation time) of tumour samples, measured in vitro, was significantly higher than normal tissue....
Although not confirmed by other workers, Damadian intended to use this and other NMR tissue parameters not for imaging but for tissue characterisation (i.e., separating benign from malignant tissue). This has remained the Holy Grail of NMR yet to be achieved due mainly to the heterogeneity of tissue. Damadian is a controversial figure in NMR circles not least for his exuberant behaviour at conferences. Although criticism has been levelled at his scientific acumen it should not overshadow the fact that his description of relaxation time changes in cancer tissue was one of the main impetuses for the introduction of NMR into medicine. On the 16th March 1973 a short paper was published in Nature entitled "Image formation by induced local interaction; examples employing magnetic resonance". The author was Paul Lauterbur, a Professor of Chemistry at the State University of New York at Stony Brook.
Damadian discovered that tumors have a different NMR relaxation time from normal tissue. The discovery had nothing to do with imaging. Imaging is what the I in MRI stands for.