Functional MRI Fine Tunes Brain Cancer Treatment Plans

DURHAM, N.C., Aug. 29 -- Functional magnetic resonance imaging (fMRI) may help surgeons more aggressively walk the line between how much brain tumor to resect without excessive damage to a patient's quality of life, researchers here said.

About half of patients with brain cancer referred for fMRI received more aggressive surgery on the basis of images of the critical language and motor areas of the brain in relation to their tumor than would have otherwise been considered, the investigators said.

"Functional MR imaging has a significant effect on therapeutic planning in patients with potentially resectable brain tumors and enables the selection of therapeutic options that might otherwise not have been considered because of functional risk," reported Jeffrey R. Petrella, M.D., of Duke, and colleagues, in the September issue of Radiology.

Of the 39 consecutive patients with potentially resectable brain tumors who were referred for fMRI by three surgeons in the study, 19 had their therapeutic plan altered (49%, 95% confidence interval: 33.0%-64.4%).

All but one of these changes were toward a more aggressive approach (46% of patients overall, P

Functional MR imaging is available at about 50 medical centers in the United States, whereas there are 12,000 MRI machines across the nation.

"It's not what I would call a common radiology procedure," Dr. Bradley said.

The Center for Medicare and Medicaid Services approved reimbursement for fMRI services beginning Jan. 1, 2007, according to the Radiological Society of North America, so its availability may expand.

The investigators used a 1.5 Tesla MR imager equipped with echo-planar imaging capabilities. To map language function in the brain, they had patients complete sentences viewed during imaging using a mirror mounted near the head coil of the MRI machine. Motor function was mapped while patients alternately squeezed one hand and then the other.

Altogether the functional MR imaging took less than an hour including training the patient to do the tasks and acquiring structural images. There were no failures due to unusable data or inability to perform tasks or technical difficulties.

The authors acknowledged that the technique may not show all of the areas of the brain that participate in a function much less differentiate truly essential functional areas. They also noted that it requires active participation by a cooperative patient, which is not always possible in this patient population.

Furthermore, referral bias may limit the findings since the three neurosurgeons involved already had some confidence in the technology and likely referred patients for whom the results might affect the treatment plan.

However, "it provides a realistic assessment of therapeutic options and the role of diagnostic functional MR imaging" in clinical practice, Dr. Petrella and colleagues wrote, "without attempting to assess its role across the entire population of potential patients."