Scientists at King's College London say the test can highlight tiny but crucial signs of autism, detectable in the scans only by a computer, the BBC reported.
Results taken from brain scans are reconstructed into a 3-dimensional image that is fed into a computer that looks for tiny but significant differences between normal brains and the brains of autism sufferers.
"What the computer can do very quickly is to see that a patient has autism," said Professor Declan Murphy from the Institute of Psychiatry, who supervised the research, "even though their brain, to the naked eye, looks very normal."
Conventional diagnosis involves a team of experts who analyze behavior and make a complex series of assessments, she said.
"It could help to alleviate the need for the emotional, time-consuming and expensive diagnostic process which (autism) patients and families currently have to endure," lead researcher Dr. Christine Ecker said.
The research team is now looking at whether the test would be effective on children, the BBC said.