Increased pressure inside the brain—the result of severe head injury, bleeding, tumors, or other neurological problems—can be fatal. That's why measuring intracranial pressure is critical in such cases. Yet the invasive methods used for measurement—drilling into the skull or opening the spinal column—carry a risk of further injury.

A noninvasive method that uses the standard magnetic resonance imaging technology already available in most hospitals is being developed by Noam Alperin, associate professor of medical physics in the department of radiology, and collaborators in neurosurgery, ophthalmology, and mechanical engineering.

"The advantage of this measurement method is that it is safe and painless," said Alperin. "Furthermore, in many instances it indicates the cause of the abnormal pressure."

The National Institutes of Health, which is funding the research, said Alperin's work represents a breakthrough that promises to have "significant clinical impact."

The method, which is patented, relies on the fact that pressure in a closed system such as the cranium is related directly to volume. The change in intracranial blood volume that occurs naturally during each cardiac cycle is calculated from the difference between blood and cerebrospinal fluid that flows in and out of the brain. This process can be visualized in a series of MRI images, repeated at short intervals, that are sensitive to motion.

Tests on baboons and humans show that measurements of intracranial pressure using this method compare favorably to those from the currently used invasive tests. More than 1.5 million people in the United States each year suffer from neurological problems caused by traumatic brain injuries, hydrocephalus, intracranial hemorrhages, tumors, and other disorders associated with abnormal intracranial pressure. These patients could benefit from Alperin's method.