Functional MR evaluation of temporal and frontal language dominance compared with the Wada test

Objective: To evaluate the reliability of temporal and frontal functional M RI (fMRI) activation for the assessment of language dominance, as compared with the Wada test. Patients and Methods: Ten patients;with temporal lobe e pilepsy were studied using blood oxygen level dependent fMRI and echoplanar imaging (1.5-T). Three tasks were used: semantic verbal fluency, covert se ntence repetition, and story listening. Data were analyzed using pixel by p ixel autocorrelation and cross-correlation. fMRI laterality indices were de fined for several regions of interest as the ratio (L - R)/(L + R), L being the number of activated voxels in the left hemisphere and R in the right h emisphere. Wada laterality indices were defined as the difference in the pe rcentages of errors in language tests between left and right carotid inject ions. Results: Semantic verbal fluency: The asymmetry of frontal activation was correlated with Wada laterality indices. The strongest correlation was observed in the precentral/middle frontal gyrus/inferior frontal sulcus ar ea. Story listening: The asymmetry of frontal, but not temporal, activation was correlated with Wada laterality indices. Covert sentence repetition: N o correlation was observed. Conclusions: There was a good congruence betwee n hemispheric dominance for language as assessed with the Wada test and fMR I laterality indices in the frontal but not in the temporal lobes. The stor y listening and the covert sentence repetition tasks increased the sensitiv ity of detection of posterior language sites that may be useful for brain l esion surgery.