Clinical Multicenter study with fMRI

With current functional magnetic resonance imaging (fMRI), large differences exist between techniques used by different fMRI centers for localizing brain activity. It is not known how variable localization results may be when the same subject is measured at different sites. Knowledge about the dependence on local methodology is utmost important however, when fMRI is applied for clinical evaluation purposes. Limits of localization confidence should be clearly known before safe surgical decisions can be made. The intention of this grant application is to provide a first country-wide multicenter study on variability of primary sensorimotor cortex localization with simple and clinically adequate stimulation paradigms. Patients admitted for routine presurgical fMRI and a control group with normal subjects shall be investigated with local standard protocols at 3 clinical fMRI centers in Vienna, Innsbruck and Salzburg. Localizations defined for presurgical patient evaluations will be validated by intraoperative cortical stimulation.

The cortex of the human brain contains several essential brain areas. E.g. areas responsible for moving the hand, areas responsible for skin sensation, areas reponsible for speaking and areas responsible for memory functions. In patients requiring brain surgery, the exact location of these brain areas has to be known to avoid harming them. Harming of essential brain areas may result in irreversible loss of the corresponding function (e.g. irreversible paresis, irreversible language deficits, irreversible memory deficits). Until recently, exact localization of such brain areas was only possible with invasive technology (e.g. anesthetizing half of a brain or performing diagnostic operations). During the last years a new, completely non invasive magnetic resonance technique has been developed (functional magnetic resonance imaging (fMRI)) to localize brain functions. The goal of this project was to investigate whether it is possible to replace the invasive technology by the new non invasive technique, which considerably reduces patient burden and patient risk. For this, the most important issue is the question of independent reproducibility of localization results with the new fMRI technology. This project localized hand movements and sensory stimulations of the hand at different austrian and german specialist centers. This allowed a first comparison of the reproducibility of functional localizations in individual patients and subjects. Results allow the conclusion, that the reliability of the new fMRI technique is good and that preference of fMRI over more invasive procedures seems justified.