''We know now it is possible to objectively differentiate the autistic brain from the typical brain using a functional MRI imaging technique," says researcher Joy Hirsch, PhD, professor of neuroscience and director of the Functional MRI Research Center at Columbia University Medical Center, New York.
However, the research is in its early stages and needs to be duplicated in larger studies, she tells WebMD. "It's an important advance, but it's not there yet," she says.
An expert who reviewed the findings tells WebMD it's more likely the scans could be used to monitor therapy for children with autism, rather than help in diagnosing autism.
Autism spectrum disorders are marked by impaired language and repetitive behaviors. They now affect up to one in 110 children, according to the CDC. The study is published online in Radiology.
Functional MRI for Autism Diagnosis: Study Details
Hirsch and her team set out to document language impairment in autistic children by using the scans.
"The idea of the study was to determine if functional imaging, which looks at both structure and function of the brain, could provide a diagnostic indicator of autism," she says.
Currently, diagnosing autism is done subjectively, Hirsch says. Parents and doctors note that a child misses important developmental milestones in language and other areas.
The researchers looked at 15 typically developing children and 12 children diagnosed with autism who had language impairment.
While the scan was being done, Hirsch says, "we had them listen to narratives that were recorded by their parents." The scans then measured the brain activity as the children listened to the narratives and encoded speech.
"We hypothesized that the autistic children would encode the language narrative less efficiently than the normal population," Hirsch tells WebMD.
They focused on two brain regions -- the primary auditory cortex, which processes sound information, and an area associated with sentence comprehension, the superior temporal gyrus (STG).
"The two groups did not differ in the response in the primary auditory cortex," Hirsch says. However, the activation within the STG was greater for the typically developing children than the autistic children.
Eventually, Hirsch says, diagnosing autism may be possible earlier by looking at these language differences using the scans.
"This is a starting point," she says. Many details are yet to be worked out, including looking at children at various levels of the autism spectrum. "Not all kids with autism have the same degree of language impairment," she says.
The average age in the two groups compared was about 12, she says. She is not certain how these findings would apply to younger children. Diagnosing autism as early as possible is crucial for early intervention and better outcomes, experts say.
The researchers also looked at another 27 children with autism who had routine MRI scans while they were sedated. Their average age was 8. Using the same scan technique, the researchers identified 26 of the 27 children with autism.
This shows the effect is still present under sedation, strengthening and extending the findings, Hirsh says.
''The results are impressive and the accuracy level is uncommon for most imaging findings," says David M. Yousem, MD, director of neuroradiology at The Johns Hopkins Medical Institution in Baltimore.
He reviewed the study findings for WebMD.
However, he says, "it is unlikely that neurologists or neuropsychologists will be using functional MRI to diagnose autism. This really is a disorder that runs much deeper than how a child's brain responds to readings."
The research, when further along, may be most useful, he says, as a way to assess children with a questionable diagnosis of autism. The scans may also be helpful, he says, to evaluate how well medicine or counseling for autism is working.