米国科学アカデミー紀要
The study opened the door to functional imaging the brain with MRI, but because the approach required the use of an intravenous contrast agent it was not suitable for wide application in humans. To address this limitation, Kenneth Kwong, a postdoctoral fellow in the NMR Center, developed a means to measure endogenous signals based on blood oxygenation using gradient echo imaging. He successfully demonstrated the technique in May 1991 and a report of the findings was published in 1992 in the Proceedings of the National Academy of Sciences of the United States of America.