Abstract
PURPOSE: To assess the concordance of pre-operative language functional MRI (fMRI) for localization of the right ventral premotor cortex (vPMC) in comparison with Direct Cortical Stimulation. METHODS AND MATERIALS: Prospective analysis was performed for 11 (n=11) patients with right-sided tumors who underwent language mapping by fMRI, followed by awake neurosurgery and intra-operative mapping by Direct Cortical Stimulation (DCS). Multi-paradigm language fMRI was performed using a standard 3-paradigm language protocol, with additional tongue movement paradigm on a Phillips Ingenia, 1.5T Scanner. The vPMC was identified as BOLD signal activation seen in at least two paradigms anterior to and discrete from the motor orofacial cortex. Pre-operative fMRI findings were validated intra-operatively using DCS with the intra-operative responses of anarthria (speech arrest) and dysarthria recorded separately. RESULTS: We obtained moderate concordance (sensitivity) of 72.2% (n=8) for anarthria (speech arrest). The vPMC was the site of speech arrest in 75% cases (n=6), followed by the oro-facial motor cortex in the remainder (n=2, 25%). Higher frequency of vPMC activation was seen with Tongue Movement and Number Counting paradigms, while that of Broca’s area with Verb Generation. Tumour size >5cm, presence of peritumoral edema and intra-tumoral haemorrhage were some of the features associated with fMRI-DCS discordance. CONCLUSIONS: vPMC detection by fMRI shows good concordance (sensitivity) with anarthria responses on Direct Cortical Stimulation. Thus, fMRI serves as a useful non-invasive tool in pre-operative planning for maximal safe resection of brain tumors.