Abstract
BackgroundFunctional magnetic resonance imaging (fMRI) continues to develop as a clinical tool for patients with brain cancer, offering data that may directly influence surgical decisions. Unfortunately, routine integration of preoperative fMRI has been limited by concerns about reliability. Many pertinent studies have been undertaken involving healthy controls, but work involving brain tumor patients has been limited. To develop fMRI fully as a clinical tool, it will be critical to examine these reliability issues among patients with brain tumors. The present work is the first to extensively characterize differences in activation map quality between brain tumor patients and healthy controls, including the effects of tumor grade and the chosen behavioral testing paradigm on reliability outcomes.MethodTest-retest data were collected for a group of low-grade (n = 6) and high-grade glioma (n = 6) patients, and for matched healthy controls (n = 12), who performed motor and language tasks during a single fMRI session. Reliability was characterized by the spatial overlap and displacement of brain activity clusters, BOLD signal stability, and the laterality index. Significance testing was performed to assess differences in reliability between the patients and controls, and low-grade and high-grade patients; as well as between different fMRI testing paradigms.ResultsThere were few significant differences in fMRI reliability measures between patients and controls. Reliability was significantly lower when comparing high-grade tumor patients to controls, or to low-grade tumor patients. The motor task produced more reliable activation patterns than the language tasks, as did the rhyming task in comparison to the phonemic fluency task.ConclusionIn low-grade glioma patients, fMRI data are as reliable as healthy control subjects. For high-grade glioma patients, further investigation is required to determine the underlying causes of reduced reliability. To maximize reliability outcomes, testing paradigms should be carefully selected to generate robust activation patterns.
Highlights
Over the last two decades, functional magnetic resonance imaging has evolved as a powerful neuroimaging technique, providing detailed maps of brain activity derived from hemodynamic responses to neuronal activity
In low-grade glioma patients, functional magnetic resonance imaging (fMRI) data are as reliable as healthy control subjects
Clinical imaging is further complicated by the effects of tumor on the blood oxygenation level-dependent (BOLD) signal, and by increased head motion often exhibited in patient populations in comparison to healthy controls [10]
Summary
Over the last two decades, functional magnetic resonance imaging (fMRI) has evolved as a powerful neuroimaging technique, providing detailed maps of brain activity derived from hemodynamic responses to neuronal activity. The brain activation maps obtained by fMRI can help the surgeon to identify regions involved in motor control [4] and language function [5], including high-risk areas that, if damaged during surgery, would likely result in a significant neurological deficit Such fMRI data may directly influence the surgical management of patients in many possible ways, such as to help determine the most feasible treatment option (e.g. craniotomy performed with or without intraoperative mapping); the necessary extent of brain exposure; the safest surgical entry point and corridor; the selection of intraoperative tasks during direct cortical stimulation (DCS); and the need for sub-cortical DCS [4,6,7,8]. The present work is the first to extensively characterize differences in activation map quality between brain tumor patients and healthy controls, including the effects of tumor grade and the chosen behavioral testing paradigm on reliability outcomes
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