The goal of this study was to document current clinical practice and report patient outcomes in presurgical language functional MRI (fMRI) for epilepsy surgery. Epilepsy surgical programs worldwide were surveyed as to the utility, implementation, and efficacy of language fMRI in the clinic; 82 programs responded. Respondents were predominantly from the US (61%) academic programs (85%), and evaluated adults (44%), adults and children (40%), or children only (16%). Nearly all (96%) reported using language fMRI. Surprisingly, fMRI is used to guide surgical margins (44% of programs) as well as language lateralization (100%). Sites using fMRI for localization most often use a distance margin around activation of 10mm. While considered useful, 56% of programs reported at least one instance of disagreement with other measures. Direct brain stimulation typically confirmed fMRI findings (74%) when guiding margins, but instances of unpredicted decline were reported by 17% of programs and unexpected preservation of function by 54%. Programs reporting unexpected decline did not clearly differ from those which did not. Clinicians using fMRI to guide surgical margins do not typically map known language-critical areas beyond Broca’s and Wernicke’s. This initial data shows many clinical teams are confident using fMRI not only for language lateralization but also to guide surgical margins. Reported cases of unexpected language preservation when fMRI activation is resected, and cases of language decline when it is not, emphasize a critical need for further validation. Comprehensive studies comparing commonly-used fMRI paradigms to predict stimulation mapping and post-surgical language decline remain of high importance.
Little is known about how language functional MRI (fMRI) is executed in clinical practice in spite of its widespread use. Here we comprehensively documented its execution in surgical planning in epilepsy. A questionnaire focusing on cognitive design, image acquisition, analysis and interpretation, and practical considerations was developed. Individuals responsible for collecting, analyzing, and interpreting clinical language fMRI data at 63 epilepsy surgical programs responded. The central finding was of marked heterogeneity in all aspects of fMRI. Most programs use multiple tasks, with a fifth routinely using 2, 3, 4, or 5 tasks with a modal run duration of 5 min. Variants of over 15 protocols are in routine use with forms of noun–verb generation, verbal fluency, and semantic decision‐making used most often. Nearly all aspects of data acquisition and analysis vary markedly. Neither of the two best‐validated protocols was used by more than 10% of respondents. Preprocessing steps are broadly consistent across sites, language‐related blood flow is most often identified using general linear modeling (76% of respondents), and statistical thresholding typically varies by patient (79%). The software SPM is most often used. fMRI programs inconsistently include input from experts with all required skills (imaging, cognitive assessment, MR physics, statistical analysis, and brain–behavior relationships). These data highlight marked gaps between the evidence supporting fMRI and its clinical application. Teams performing language fMRI may benefit from evaluating practice with reference to the best‐validated protocols to date and ensuring individuals trained in all aspects of fMRI are involved to optimize patient care.
The goal of this study was to document current clinical practice and report patient outcomes in presurgical language functional MRI (fMRI) for epilepsy surgery. Epilepsy surgical programs worldwide were surveyed as to the utility, implementation, and efficacy of language fMRI in the clinic; 82 programs responded between July 2015 and January 2016. Respondents were predominantly from the US (61%), were academic programs (85%), and predominantly evaluated adults (44%), both adults and children (40%), or children only (16%). Nearly all (96%) respondents reported using language fMRI. fMRI is used for language lateralization (100%) and for localizing (44%) language cortex to guide surgical margins. While typically considered useful, programs often reported at least one instance of disagreement with other measures (56%). When used to localize language cortex, direct brain stimulation typically confirmed fMRI findings (74%) but instances of unpredicted decline were reported by 17% of programs and unexpected preservation of function were reported by 54%. Programs reporting unexpected decline did not clearly differ from those which did not. Clinicians using fMRI to guide surgical margins typically map Broca's and Wernicke's areas but not other known language areas. Language fMRI is widely used for lateralizing language cortex in patients with medically intractable epilepsy. It is also frequently used to localize language cortex though it is not yet well validated for this purpose. Many centers report cases of unexpected language preservation when fMRI activation is resected, and cases of language decline when it is not. Care will almost certainly be improved by standardizing protocols and accurately detailing the relationship between fMRI-positive areas and post-surgical language decline.. CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under aThe copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/185835 doi: bioRxiv preprint first posted online Sep. 7, 2017; Presurgical language fMRI: Current Practices Benjamin et al. 2 IntroductionNeurosurgery is an effective and potentially curative treatment for temporal lobe epilepsy.1 Surgical risk to language and memory can exclude a patient from treatment. As 34%-41% of left temporal patients undergoing focal resections experience a decline in naming, 2,3 determining the surgical risk to language remains essential.While the Intracarotid Amobarbital Test ("Wada" testing) has been the gold standard for determining the language dominant hemisphere, functional magnetic resonance imaging (fMRI) can be accurate 4 and less costly, 5 and is non-invasive. The evidence supporting fMRI's validity was recently outlined, 6 with the conclusion that language fMRI is a valid alternative to Wada testing in most patients. One approach to incorporating fMRI in clinical decision making developed by Swanson and colleagues. 7 In short, if language fMRI shows left hemisphere dominance and a patient has right hemisphe...
Little is known about how language functional MRI (fMRI) is executed in clinical practice in spite of its widespread use. Here we comprehensively documented its execution in surgical planning in epilepsy. A questionnaire focusing on cognitive design, imaging acquisition, analysis and interpretation and practical considerations was developed. Individuals responsible for collecting, analyzing, and interpreting clinical language fMRI data at 63 epilepsy surgical programs responded. The central finding was of marked heterogeneity in all aspects of fMRI. Most programs use multiple tasks, with a fifth routinely using 2, 3, 4 or 5 tasks with a modal run duration of five minutes. Variants of over fifteen protocols are in routine use with forms of noun-verb generation, verbal fluency, and semantic decision-making used most often. Nearly all aspects of data acquisition and analysis vary markedly. Neither of the two best-validated protocols were used by more than 10% of respondents. Preprocessing steps are broadly consistent across sites, language-related blood flow is most often identified using general linear modeling (76% of respondents), and statistical thresholding typically varies by patient (79%). The software SPM is most often used. fMRI programs inconsistently include input from experts with all required skills (imaging, cognitive assessment, MR physics, statistical analysis, brain-behavior relationships). These data highlight marked gaps between the evidence supporting fMRI and its clinical application. Teams performing language fMRI may benefit from evaluating practice with reference to the best-validated protocols to date and ensuring individuals trained in all aspects of fMRI are involved to optimize patient care.
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