Abstract: |
In the early 1990s, functional magnetic resonance imaging (fMRI) entered the field of neuroimaging as a unique resource in the arsenal of preoperative planning tools for brain tumor patients. fMRI is a technique that takes advantage of the differences in magnetic susceptibility between oxyhemoglobin and deoxyhemoglobin. It is a less invasive neuroimaging method than its positron emission tomography (PET) predecessor given that the contrast agent is endogenous [1]. fMRI is possible because oxyhemoglobin has a different magnetic resonance signal than deoxyhemoglobin. When a task is performed, oxygenated blood in excess of the amount needed (termed luxury perfusion) is delivered to the active area. The difference in magnetic susceptibility between deoxyhemoglobin concentrations and oxyhemoglobin concentrations creates the signal in functional imaging. This effect is termed the blood oxygen level-dependent signal (BOLD signal). fMRI provides good spatial localization (as low as 1 mm) and temporal acquisition resolution (as low as 1 s) though it is limited by the resolution of the hemodynamic response (8-30 s). The superior spatial resolution is particularly advantageous for mapping peri-tumoral eloquent areas for treatment planning [2]. © Springer Science+Business Media New York 2014. All rights are reserved. |