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

Abstract

AbstractIntroductionResting-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 methodsFunctional 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.ResultsOnly 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.ConclusionThe 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.