Detection and Mitigation of Neurovascular Uncoupling in Brain Gliomas

SIMPLE SUMMARY: We discussed the reliability of fMRI for in vivo evaluation of eloquent cortex, which helps to reduce the risk of postsurgical morbidity. Task-based fMRI (tb-fMRI) is commonly utilized for the noninvasive, accurate evaluation of eloquent cortex implicated in sensorimotor, language, and visual function. Resting-state fMRI (rs-fMRI) is being increasingly employed in addition to tb-fMRI and may be able to serve as an adjunct for tb-fMRI for presurgical mapping in the future. There is, however, a need to confirm the reliability of rs-fMRI data in various clinical contexts, and more validation and standardization is necessary prior to adopting this tool for daily clinical care. Although tb-fMRI has been proved to be a trustworthy method, the problem of neurovascular uncoupling (NVU) needs to be addressed to give the most accurate functional evaluation in clinical practice. Breath-hold cerebrovascular reactivity (BH-CVR) methods can be used to assess risk of NVU. We hope that future research will investigate and overcome the problem of NVU encountered in presurgical brain mapping with BOLD fMRI. ABSTRACT: Functional magnetic resonance imaging (fMRI) with blood oxygen level-dependent (BOLD) technique is useful for preoperative mapping of brain functional networks in tumor patients, providing reliable in vivo detection of eloquent cortex to help reduce the risk of postsurgical morbidity. BOLD task-based fMRI (tb-fMRI) is the most often used noninvasive method that can reliably map cortical networks, including those associated with sensorimotor, language, and visual functions. BOLD resting-state fMRI (rs-fMRI) is emerging as a promising ancillary tool for visualization of diverse functional networks. Although fMRI is a powerful tool that can be used as an adjunct for brain tumor surgery planning, it has some constraints that should be taken into consideration for proper clinical interpretation. BOLD fMRI interpretation may be limited by neurovascular uncoupling (NVU) induced by brain tumors. Cerebrovascular reactivity (CVR) mapping obtained using breath-hold methods is an effective method for evaluating NVU potential.