Several technical advances have contributed to MRI's improvement. Topping the list is the development of more-powerful MRI magnets, which enable more-detailed, higher-resolution scans. What megapixels are for a digital camera, teslas, a measure of magnetic-field strength, are for MRIs: the more you have, the better the quality of the image. The newest MRIs generate magnetic fields of about seven teslas, many thousands of times stronger than Earth's magnetic field and at least twice as strong as those typically used in hospitals. (Some research centers, including the McGovern Institute, have 9.4-tesla MRI scanners for animal studies.)

Another key development is a succession of ever more complex methods of computer analysis. These allow researchers to extract more and better information from scanner data and have improved not just fMRI but also MRI spectroscopy and DTI.

The ultimate aim of brain imaging research is to help explain how the billions of neurons and connections in the brain give rise to thought. But researchers are also applying the new MRI techniques to a more practical, immediate goal: improving the diagnosis and treatment of mental illnesses and learning disorders. The hope is that MRI imaging will provide far more accurate diagnosis of psychiatric diseases whose symptoms can resemble each other, preventing years of suffering for patients put on the wrong medications.

As part of this effort, researchers are using MRI to investigate the causes not only of psychiatric ailments but of all kinds of brain abnormalities and learning disorders, including those often found in children born prematurely. And while attempts to use brain imaging to improve psychiatric health care have met with little success over the last decade, the new MRI technologies -- in essence, far stronger telescopes on the mind -- are providing fresh hope of finding better ways to intervene.

Bipolar Fingerprint

One of the leaders in the effort to enlist MRI in the diagnosis and treatment of psychiatric ailments is John Port at the Mayo Clinic in Rochester, MN. Port is a neuroradiologist who began his career by studying electrical engineering and computer science at MIT and later earned a PhD in cell biology and an MD from the University of Illinois. So he's in a good position to research both basic MRI technology and its applications to medicine.

Port's work on MRI could have broad application in psychiatry, but for now he is concentrating on his particular interest: bipolar disorder. Also called manic-depression, bipolar disorder is characterized by mood swings from wild exuberance to profound depression, with periods of stability in between. X-rays or conventional MRIs show no difference between the brains of people with bipolar disorder and those without it; medical journals are littered with failed attempts to use imaging to find distinctive signs of the disease.

Port thinks a lot of those attempts were scientifically flawed. "I have a list of pet peeves a mile long," he says. "There are a million studies, but the patients might be on six different medications. So when you see something different, is it the meds? Or is something going on?" Another problem with many earlier studies, he says, is that they included too few patients. "You can't tell anything from 10 patients. A lot of the research hasn't been as rigorous as it should be."