Value of frequency domain resting state fMRI metrics ALFF & fALFF in the assessment of brain tumor-induced neurovascular uncoupling.

Brain Connect. 2017 Jun 28;:

Authors: Agarwal S, Lu H, Pillai JJ

Abstract
AIM: To explore whether the phenomenon of brain tumor-related neurovascular uncoupling (NVU) in resting state BOLD fMRI (rsfMRI) may also affect the rsfMRI frequency domain metrics ALFF (the amplitude of low-frequency fluctuation) & fALFF (fractional ALFF).
METHODS: Twelve de novo brain tumor patients who underwent clinical fMRI exams including task-based fMRI (tbfMRI) and rsfMRI were included in this IRB-approved study. Each patient displayed decreased/absent tbfMRI activation in the primary ipsilesional sensorimotor cortex in the absence of a corresponding motor deficit or suboptimal task performance, consistent with NVU. Z-score maps for the motor tasks were obtained from general linear model (GLM) analysis (reflecting motor activation vs. rest). Seed-based correlation analysis (SCA) maps of sensorimotor network, ALFF, and fALFF were calculated from rsfMRI data. Precentral and postcentral gyri in contralesional (CL) and ipsilesional (IL) hemispheres were parcellated using an Automated Anatomical Labeling (AAL) template for each patient. Region of Interest (ROI) analysis was performed on four maps: tbfMRI, SCA, ALFF, fALFF.
RESULTS: Voxel values in the CL & IL ROIs of each map were divided by the corresponding global mean of ALFF & fALFF in the cortical brain tissue. Group analysis revealed significantly decreased IL ALFF (p=0.02) and fALFF (p=0.03) metrics compared to CL ROIs, consistent with similar findings of significantly decreased ipsilesional BOLD signal for tbfMRI (p=0.0005) & SCA maps (p=0.0004).
CONCLUSION: The frequency domain metrics ALFF & fALFF may be markers of lesion-induced NVU in rsfMRI similar to previously reported alterations in tbfMRI activation & SCA-derived resting state functional connectivity maps.

PMID: 28657344 [PubMed - as supplied by publisher]