A comparison of fMRI presurgical mapping techniques with intraoperative brain mapping-based validation

Introduction Resting-state functional MRI (rs-fMRI) could enable preoperative risk assessment and intraoperative guidance for patients who cannot undergo task-based fMRI (tbfMRI). We investigated differences in accuracy between tbfMRI and rsfMRI acquired with single (sTE) at voxel size of 2mm and 3mm, and multi-echo (mTE) scans using intraoperative mapping with direct electrical stimulations (DES) as the ground truth. Material and methods Functional sensory-motor mapping results of hands and feet were spatially compared relative to positive (pDES, functional effect) and negative (nDES, no functional effect) coordinates in 16 preoperative patients. General linear model analysis was used for tbfMRI, and seed-based analysis (SBA) for rsfMRI. Minimum Euclidean distances between fMRI and DES were calculated and compared between fMRI methods. Receiver-operating characteristic (ROC) curves were used to compare accuracy and determine distance cutoffs for fMRI agreement with DES, and binary agreement rates were compared at different cutoffs. Two-part mixed-effects linear models were used to compare fMRI methods while accounting for unequal inter-subject DES repetition. Results Only minor differences were found between fMRI methods in unthresholded distances (mean differences ~ 2 mm). ROCs and binary agreement measures showed comparable accuracy for tbfMRI and sTE-rsfMRI 2mm, but mildly worse for sTE-rsfMRI 3mm and mTE-rsfMRI. However, differences in relative accuracy between sTE- and mTE-rsfMRI were minor when the same distance cutoff was applied to all methods. This was also reflected on comparing rates of binary agreement and confirmed by the two-part linear models, which showed no significant differences between fMRI methods and a significant effect of DES response. Conclusion The similar accuracy for SBA rsfMRI functional sensory-motor mapping compared to tbfMRI for the hands and feet, indicate that rsfMRI may be suitable for presurgical mapping. The differences in relative accuracy between sTE- and mTE rsfMRI warrant further investigation in a larger sample. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of University hospitals of Leuven (UZ Leuven), campus Gasthuisberg, and the University of Leuven (KU Leuven) gave ethical approval for this work with study number S61759 I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available after anonymisation upon reasonable request to the authors within the limitations imposed by GDPR