"However, his idea was a fundamental discovery which also led to MRI, positron emission tomography (PET), single photon emission computed tomography (SPECT), and other imaging techniques.Once these techniques became widely accepted, Dr. Oldendorf, along with William Markley McKinney, MD (1930–2003) were instrumental in promoting the use of Computed Tomography among neurologists to help decrease the use of superfluous and invasive tests.