Disruption of the normal coupling between neural activity and the consequent microvascular blood flow response (neurovascular uncoupling, or NVU) may severely compromise the validity of BOLD fMRI in pre-surgical planning.¹ The effects of brain tumor-related NVU on task-based BOLD fMRI (tbfMRI) have been previously published², and similar effects of NVU on resting state BOLD fMRI (rsfMRI) have been demonstrated using ICA (i.e. independent component analysis) and SCA (seed based correlation analysis).³ In this study we evaluated regional homogeneity (ReHo) of rsfMRI data based on Kendall's coefficient of concordance (KCC-ReHo)⁴ & Coherence (Cohe-ReHo)⁵ and compared the results with the amplitude of low-frequency fluctuation (ALFF)⁶ & standard motor tbfMRI activation to investigate regional abnormalities due to brain tumor-induced NVU in sensorimotor network.Seven patients with perirolandic primary gliomas referred for presurgical motor mapping with BOLD fMRI were included in this IRB-approved study. Each patient demonstrated NVU as evidenced by abnormally decreased or absent tbfMRI activation in ipsilesional (IL) compared to contralesional (CL) primary motor cortex despite absence of clinical motor deficits². Imaging was performed on a 3.0 T Siemens Trio MRI with a 12-channel head matrix coil. Imaging protocol included 3D T1 MPRAGE (TR=2300 ms, TI= 900 ms, TE= 3.5 ms, 9° FA, 24-cm FOV, 256x 256x176 matrix, slice thickness 1 mm) structural and multiple 2D GE-EPI T2* weighted BOLD sequences for both tbfMRI and rsfMRI (TR=2000 ms, TE=30 ms, 90° FA, 24-cm FOV, 64x64x33 matrix, 4 mm slice thickness with 1 mm gap between slices, interleaved acquisition). 180 volumes were acquired in a 6 minute duration rsfMRI scan. Vertical tongue movement and bilateral simultaneous sequential finger tapping tasks (each 3 minutes duration with alternating 30 seconds blocks of movement and rest were used for tbfMRI. Instructions for all tasks were visually cued. SPM12 was used for preprocessing of tbfMRI & rsfMRI data (slice timing correction, realignment, normalization to MNI space at 2mm voxel resolution, and spatial smoothing using a 4 mm FWHM Gaussian kernel). T-value maps for the motor tasks were obtained from the general linear model (GLM) analysis using standard SPM canonical HRF (reflecting motor activation vs. rest). Pre-processed rsfMRI data were analyzed using the REST(version 1.8)⁷ toolkit. After detrending and low frequency (0.01-0.08 Hz) bandpass filtering, ALFF, KCC-ReHo & Cohe-ReHo were calculated. For ROI analysis, pre- and post- central gyri were automatically parcellated using an Automated Anatomical Labeling (AAL) template^8,9 for each patient. Cl and IL ROIs circumscribing the combination of pre- and post- central gyri (CG) were obtained for each slice. Consecutive axial sections were evaluated along the z-axis where NVU-affected impaired IL motor activation was present on tbfMRI. Identical ROIs were used for analysis of the tbfMRI, ALFF, KCC-ReHo and Cohe-ReHo maps.Group analysis demonstrated significantly decreased KCC-ReHo and Cohe-ReHo in the IL ROIs compared to the CL reference ROIs (based on number of nonzero voxels in the respective ROIs (p=0.03)). These findings correspond to similar IL BOLD signal reductions on tbfMRI (p=0.03) that suggest NVU in these patients without clinical motor deficits & similar IL reductions of ALFF (p=0.03). However, no significant differences in mean values of these metrics (p=0.02 for KCC & p=0.08 for Cohe-ReHo) was seen in the IL ROIs compared to the CL ROIs, although a trend-level difference was seen for Cohe-ReHo. Figure 1 displays results for a single patient.In this preliminary study we have demonstrated that tumor-induced ipsilesional abnormalities on ReHo appear to highlight the same regional abnormalities seen on tbfMRI activation maps in cases of known NVU.Ipsilesional abnormalities in ReHo derived from rsfMRI may serve as a potential indicator of NVU in patients with brain tumors and other resectable brain lesions; as such, ReHo findings may complement findings on tbfMRI used for presurgical planning.