Objective: To evaluate the concordance of language lateralization between functional magnetic resonance imaging (fMRI) using Thai version of language paradigm and Wada test or awake surgery with direct cortical brain stimulation (DCS).

Material and Method: Retrospective study of thirteen patients (3 males and 10 females with mean age of 33.9 years old) with epilepsy (7 cases) or brain tumor (6 cases) was performed. Every patient underwent both fMRI (word generation, verb generation, naming picture, and sentence completion tasks) and Wada test or awake surgery with DCS (defined as the gold standard). The lateralization index (LI) of fMRI was automatically calculated by using the LI-toolbox on SPM8. The hemispheric lateralization was also evaluated visually. The concordance between fMRI and gold standard were analyzed.

Results: The concordance between the lateralization of fMRI by visual assessment and gold standard was 92.3%. Concordance between the calculated LI by fMRI and gold standard was varied along with the task and regional calculation method. The concordance was good in all tasks (except for naming picture task) when using calculated LI from frontal or whole brain excluded cerebellum and occipital lobe (range 76.92 to 88.98% and 76.92 to 92.31%, respectively).

Conclusion: There was good concordance between fMRI and gold standard. Regional calculation from frontal lobes and whole brain excluded cerebellum and occipital lobes gave the best results. The results supported feasibility to use the fMRI with Thai language paradigm as an alternative way to determine the language dominant hemisphere in Thai patients. In case of language dominant hemisphere is unclear, further invasive investigation of language mapping such as Wada test or DCS is crucial.

Keywords: Functional MRI, Thai, Language, Wada test