Functional MRI for Language Localization

Abstract

Language Dominance in Partial Epilepsy Patients Identified with an fMRI Reading Task Gaillard WD, Balsamo L, Xu B, Grandin CB, Braniecki SH, Papero PH, Weinstein S, Conry J, Pearl PL, Sachs B, Sato S, Jabbari B, Vezina LG, Frattali C, Theodore WH Neurology 2002;59(2):256–265 Background Functional magnetic resonance imaging (fMRI) language tasks readily identify frontal language areas; temporal activation has been less consistent. No studies have compared clinical visual judgment with quantitative region-of-interest (ROI) analysis. Objective To identify temporal language areas in patients with partial epilepsy by using a reading paradigm with clinical and ROI interpretation. Methods Thirty patients with temporal lobe epilepsy, aged 8 to 56 years, had 1.5-T fMRI. Patients silently named an object described by a sentence compared with a visual control. Data were analyzed with ROI analysis from t-maps. Regional asymmetry indices (AIs) were calculated ([L-R]/[L+R]), and language dominance defined as >0.20. t-Maps were visually rated by three readers at three t thresholds. Twenty-one patients had the intracarotid amobarbital test (IAT). Results The fMRI reading task provided evidence of language lateralization in 27 of 30 patients with ROI analysis. Twenty-five were left dominant, two right, one bilateral, and two were nondiagnostic; IAT and fMRI agreed in most patients; three had partial agreement, and none overtly disagreed. Interrater agreement ranged between 0.77 to 0.82 (Cramer V; p < 0.0001); agreement between visual and ROI reading with IAT was 0.71 to 0.77 (Cramer V; p < 0.0001). Viewing data at lower thresholds added interpretation to 12 patients on visual analysis and eight with ROI analysis. Conclusions An fMRI reading paradigm can identify language dominance in frontal and temporal areas. Clinical visual interpretation is comparable to quantitative ROI analysis.