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Functional magnetic resonance imaging
Last reviewed: 07.07.2025
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Functional MRI is based on the increase in blood flow in the brain in response to an increase in neuronal activity in the cortex when exposed to a corresponding stimulus. Mapping brain activity allows us to identify areas of neuronal activation that arise in response to stimulation (motor, sensory and other stimuli).
The use of a pulsed echoplanar sequence based on gradient echo allows recording a high-intensity MR signal from active areas of the cerebral cortex, with the recording time of one MR image being about 100 ms. In functional MRI, the intensity of signals recorded under physiological load (activation) and in its absence (control) is compared. Areas of statistically significant increase in the MR signal, identified during subsequent mathematical processing of images, correspond to areas of neuronal activity in the brain. They are highlighted in color, maps of neuronal activity are constructed and superimposed on T1-MRI or a three-dimensional model of the brain surface.
Clinical application of functional MRI. Mapping of the brain's neuronal activity zones allows planning a surgical approach and studying pathophysiological processes in the brain. The method is used in neuropsychology to study cognitive functions of the brain. It is promising for identifying epilepsy foci.
The use of functional MRI has now become an integral part of the MRI protocol in patients with brain tumors located near functionally significant areas of the cerebral cortex. In most cases, the results obtained adequately reflect the location of the sensorimotor, speech and auditory areas of the cerebral cortex. Functional MRI (currently performed only for the somatosensory and visual cortex), tractography with the construction of maps of the functionally significant area of the cortex, pyramidal or optic tract and their imposition on a three-dimensional image of the brain are promising within the framework of a single MR study in patients with brain tumors. Based on the combination of the obtained data, neurosurgeons plan the surgical approach and the volume of tumor resection, and radiologists calculate the areas of tumor radiation dose distribution.
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