Clinical practice of language fMRI in epilepsy centers: a European survey and conclusions by the ESNR Epilepsy Working Group

Abstract

Purpose To assess current clinical practices throughout Europe with respect to acquisition, implementation, evaluation, and interpretation of language functional MRI (fMRI) in epilepsy patients. Methods An online survey was emailed to all European Society of Neuroradiology members (n = 1662), known associates (n = 6400), and 64 members of European Epilepsy network. The questionnaire featured 40 individual items on demographic data, clinical practice and indications, fMRI paradigms, radiological workflow, data post-processing protocol, and reporting. Results A total of 49 non-duplicate entries from European centers were received from 20 countries. Of these, 73.5% were boardcertified neuroradiologists and 69.4% had an in-house epilepsy surgery program. Seventy-one percent of centers performed fewer than five scans per month for epilepsy. The most frequently used paradigms were phonemic verbal fluency (47.7%) and auditory comprehension (55.6%), but variants of 13 paradigms were described. Most centers assessed the fMRI task performance (75.5%), ensured cognitive-task adjustment (77.6%), trained the patient before scanning (85.7%), and assessed handedness (77.6%), but only 28.6% had special paradigms for patients with cognitive impairments. fMRI was post-processed mainly by neuroradiologists (42.1%), using open-source software (55.0%). Reporting was done primarily by neuroradiologists (74.2%). Interpretation was done mainly by visual inspection (65.3%). Most specialists (81.6%) were able to determine the hemisphere dominance for language in more than 75% of exams, attributing failure to the patient not performing the task correctly. Conclusion This survey shows that language fMRI is firmly embedded in the preoperative management of epilepsy patients. The wide variety of paradigms and the use of non-CE-marked software underline the need for establishing reference standards.

Roles of fMRI and Wada tests in the presurgical evaluation of language functions in temporal lobe epilepsy

“…There are, however, simplified protocols that have been adapted to overcome this limitation (74). Further problems with fMRI include the lack of a consensus on the optimal fMRI protocol for language testing (75). The results also depend on the data analysis software and image pre-processing pipeline, as well as the threshold and ROI chosen.…”

The Effect of Right Temporal Lobe Gliomas on Left and Right Hemisphere Neural Processing During Speech Perception and Production Tasks

“…First, to reduce the risk of post-operative language deficits it is important for neurosurgeons to understand which brain regions might be compensating for the function of the region affected by the tumour so that these compensatory regions can be preserved during resection ( Duffau, 2006 , 2005 ). In addition to performing routine clinical fMRI tasks which can help to identify interhemispheric lateralisation of language activation ( Black et al, 2017 ; Bargalló et al, 2020 ) additional preoperative fMRI tasks could be tailored depending upon which particular brain regions are affected by the tumour, and what is known about the function of these regions in the neurologically intact brain. For tumours affecting the right postero-superior temporal lobe, given the pre-existing knowledge of the function of RpSTS and the findings from this study, we would recommend using a two-object naming task performed with overt speech production (as has been used in this study) which has high consistency of reproducible activation across participants ( Ekert et al, 2021 ).…”

Testing an Adapted Auditory Verbal Learning Test Paradigm for fMRI to Lateralize Verbal Memory in Patients with Epilepsy

“…American and European task forces from the American College of Radiology and European Society of Neuroradiology have worked diligently to standardize the use of language fMRI in clinical practice. 26 However, the nature of memory is complex, and activation depends on the task, paradigm design, data acquisition, and analysis. Tasks have varied across memory fMRI studies, leading to unsuccessful result replication.…”