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Background and Objectives It remains to be determined whether noninvasive functional imaging techniques can rival the clinical potential of direct electrocortical stimulation (DES). In this study, we compared the results of resting-state functional magnetic resonance imaging (rs-fMRI) to those of DES for language mapping. Our goals were twofold: (1) to replicate a previous study that demonstrated that resting-state connectivity (RSC) was significantly larger between positive DES language sites than between negative DES language sites and (2) to compare the spatial resolution of rs-fMRI to that of DES. Methods We conducted a retrospective study of nine low-grade glioma patients. Language sites were identified by intraoperative DES. We compared RSC values between and within groups of DES-positive and DES-negative regions of interest (ROIs). Both close-negative sites (i.e., DES-negative sites Results Functional connectivity between all positive language sites was on average significantly higher than between all close-negative sites and between all far-negative sites. The functional connectivity between the positive language ROIs and their respective close-negative control sites was not smaller than between all positive language sites. Conclusion rs-fMRI likely reflects similar neural information as detected with DES, but in its current form does not reach the spatial resolution of DES.

In this work, electrocorticographic temporal alteration mapping (ETAM) was proposed for motor cortex mapping by utilizing movement-related cortical potentials (MRCPs) within [0.05 3] Hz low frequency band. This MRCP waveform-based temporal domain approach was compared with the state-of-the-art electrocorticographic frequency alteration mapping (EFAM), which was based on high frequency spectrum dynamics. Five patients (2 epilepsy cases and 3 tumor cases) were enrolled in this study. Each patient had intraoperative direct electrocortical stimulation (DECS) procedure for motor cortex localization, and the patient was required to perform simple brisk wrist extension task during awake craniotomy surgery. Cross-validation results shown that the proposed ETAM method had a high performance in sensitivity (81.82%) and specificity (94.33%) for identifying sites which exhibited positive DECS motor responses. No significant difference in sensitivity was observed between ETAM and EFAM methods. However, the proposed ETAM was much higher in specificity as compared with EFAM (94.33% vs. 86.08%). Our results indicated that for the intraoperative functional brain mapping, ETAM was a promising novel approach for motor cortex localization and had a great potential to reduce the needs for cortical electrical stimulation.

Mapping functional areas of the brain is important for planning tumour resections. With the increased use of functional magnetic resonance imaging (fMRI) for presurgical planning, there is a need to validate that fMRI activation mapping is consistent with the mapping obtained during surgery using direct electrocortical stimulation (DECS).A quantitative comparison of DECS and fMRI mapping techniques was performed, using a patient-specific conductivity model to find the current distribution resulting from each stimulation site. The resulting DECS stimulation map was compared to the fMRI activation map, using the maximal Dice similarity coefficient (MDSC).Our results show some agreement between these two mapping techniques--the stimulation site with the largest MOSC was the only site that demonstrated intra-operative effect.There is a substantial effort to improve the techniques used to map functional areas, particularly using fMRI. It seems likely that fMRI will eventually provide a valid non-invasive means for functional mapping.