Scanners can help combat depression, a US study of rats shows.
Doctors had already reported scanners helping treat depression in patients
Harvard Medical School researchers found MRI scanners, which take internal images of the body, can have the same effect as standard anti-depressants.
The team employed a rarely-used type of scan known as EP-MRSI which tends to be used for brain scans.
But UK experts said they were sceptical about the findings and said more research was needed.
The team found rats experiencing stress and exhibiting helplessness - the rat equivalent of despair - recovered significantly when exposed to EP-MRSI, the journal Biological Psychiatry reported.
The scientists carried out the study after doctors reported similar effects in human patients with bipolar disorder.
Lead researcher Dr Bruce Cohen, a psychiatrist at the McLean Hospital in Massachusetts, which is affiliated to Harvard Medical School, said the findings had the potential to revolutionise depression treatment.
"The rats behaved as if they had received an anti-depressant. It's a non-drug way to change the firing of nerve cells.
"That's why the implications of this work have the potential to be so profound."
But William Carlezon, who also took part in the study, added it could also mean that some forms of MRI could be damaging to patients.
"Renewed caution is warranted when high-speed MRI is used to diagnose or study disorders involving the brain.
"People assume when they are getting an MRI that nothing is happening, that you are simply getting a picture of the brain.
"But in actuality the body is being exposed to magnetic and electrical fields.
"They may cause other effects we don't understand yet."
But consultant psychiatrist Cosmo Hallstrom, of the Royal College of Psychiatrists, said the report should be treated with caution.
"Not many rats are like patients so we have to be careful when we interpret findings based on animal models.
"I have not heard of MRI scans having this effect nor have I heard of any of the millions of people who have them suffering harm. I am surprised by the findings, we need to look into this further."