Clinical functional MRI for language mapping: Best Practice recommendations from the Organization for Human Brain Mapping

Ample reports highlight fMRI’s added value to guide and tailor neurosurgical interventions near brain regions supporting speech and language. However, fMRI’s usefulness for clinical language mapping remains controversial. This controversy is partly fueled by 1) differences between fMRI and the tools it is often compared against, and 2) wide heterogeneity in how clinical fMRI data are acquired, analyzed and interpreted. Both factors limit the objective assessment of the benefits and efficacy of presurgical fMRI.The OHBM Working Group on clinical fMRI language mapping was formed in 2017. Its scope was to review and propose best practice recommendations addressing the specific challenges posed by applications in patient populations. The first objective was to consider language tasks, and task designs, optimized for specific clinical objectives, and incorporating modifications for patients with language- and broader cognitive impairment. The second objective was to put forward practical guidance, based on high-quality research, for each stage of the workflow from fMRI acquisition and analysis through to the reporting of individual patients' data.In considering these challenges we focus on implementations that have proven practically feasible based on existing approaches (tasks, software packages) actively in use today. When widely available practices deviate from optimal practices, we highlight emerging developments that merit further evaluation and incorporation into routine clinical use to advance the current practices.This document was created in collaboration with the OHBM Committee on Best Practices, incorporating community feedback. Its aims are to provide a framework for improved standardization of fMRI to enable much needed evaluations of its ultimate goals; namely, minimization of invasive intraoperative testing and, ultimately, of new post-operative language deficits. In this regard, the single strongest recommendation is for greater transparency and reporting of longitudinal outcomes in patients undergoing clinical fMRI.