Language functional magnetic resonance imaging in preoperative assessment of language areas: Correlation with direct cortical stimulation

OBJECTIVE: The aim of this study was to: analyze the usefulness of preoperative language functional magnetic resonance imaging (fMRI) by correlating fMRI data with intraoperative cortical stimulation results for patients with brain tumors. METHODS: Naming and verb generation tasks were used separately or in combination, for 14 right-handed patients with tumors in the left hemisphere. fMRI data obtained were analyzed with SPM software, with two standard analysis thresholds (P < 0.005 and then P < 0.05). The fMRI data were then registered in a frameless stereotactic neuronavigational vice and correlated with direct brain mapping results. We Used a statistical model with the fMRI information as a predictor, spatially correlating each intraoperatively mapped cortical site with fMRI data integrated in the neuronavigational system (site-by-site correlation). Eight patients were also studied with language fMRI postoperatively, with the same acquisition protocol. RESULTS: We observed high variability in signal extents and locations among patients with both tasks. The activated areas were located mainly in the left hemisphere in the middle and inferior frontal gyri (F2 and F3), the superior and middle temporal gyri (T1 and, T2), and the supramarginal and angular, gyri. A total of 426 cortical sites were tested for each task among the, 14 patients. In frontal and temporoparietal areas, poor s sitivity of the WRI technique 'Was observed for, the naming and verb generation I tasks (22 and 36%, respectively) with P < 0.005 as the analysis threshold. Although not perfect, the specificity of the fMRI technique was good in all conditions (97% for the naming task and 98% for the verb generation task). Better correlation (sensitivity, 59%; specificity, 97%) was achieved by combining the two fMRI tasks. Variation of the analysis threshold to P < 0.05 increased the sensitivity to 66% while decreasing the specificity to 91%. Postoperative fMRI data, (for the cortical brain areas studied intraoperatively) were in, accordance,with brain mapping results for six of eight patients. Complete agreement between pre- an j postop erative WRI studies and'direct 7 brain, mapping results was observed for only. three of eight patients. CONCLUSION: With the paradigms thresholds used in this study, language fMRI data obtained with naming 9 verb, generation tasks, before and after surgery, were imperfectly correlated with intraoperative brain mapping results. A better correlation could be obtained by combining the fMRI tasks. The overall results, of this study demonstrated that-language fMRI could not be used to make critical surgical decisions in the absence of direct brain,mapping. Other acquisition protocols are required for evaluation of the potential role of language fMRI in the accurate detection of essential cortical language areas.