Language mapping in less than 15 minutes: Real-time functional MRI during routine clinical investigation

Neurosurgical interventions often require the presurgical determination of language dominance or mapping of language areas. Results obtained by fMRI a re closely correlated with invasive procedures such as electrical stimulati on mapping or the intracarotid amobarbital test. However, language fMRI is not used routinely, because postprocessing is time-consuming. We utilized a real-time analysis software installed directly on the AM console computer and SPM99 as reference postprocessing software. We assessed the reliability of the immediate determination of language dominance based on individual a ctivation maps by comparing the results of the visual analysis of images de rived from conventional postprocessing with those produced by the real-time tool. All images were rated independently by six senior neurologists blind ed to other data. We validated the robustness of the realtime method statis tically by comparing global and regional lateralization indices derived fro m real-time and postprocessing analysis. Functional MRI was performed with a standard 1.5-T whole-body scanner. Brain activity was contrasted between an alternating semantic judgment and letter matching task. Twelve right-han ded, healthy control subjects and 12 consecutive patients with drug-resista nt, localization-related epilepsy were investigated. The semantic condition induced almost invariably left hemispheric activations in Broca's area, th e premotor cortex, the dorsolateral prefrontal cortex, and the temporoparie tal region. Although real-time analysis reduced noise less effectively than SPM99, visual ratings and lateralization indices produced highly concordan t results with both methods. In conclusion, real-time MRI, as used here, al lowed reliable language lateralization and mapping in less than 15 min duri ng routine clinical MRI investigation with no need for postprocessing. (C) 2001 Academic Press.