Functional magnetic resonance imaging
Last reviewed: 23.04.2024
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Functional MRI is based on increased blood flow in the brain in response to an increase in neuronal activity of the cortex under the action of the corresponding stimulus. Mapping of 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 pulse echoplane sequence based on the gradient echo allows one to register a high-intensity MP signal from the active regions of the cerebral cortex, and the recording time of one MR image is about 100 ms. With a functional MRI, the intensity of signals recorded at physiological loading (activation) and in its absence (control) is compared. The areas of statistically significant increase in the MR signal, revealed during the subsequent mathematical processing of images, correspond to the areas of brain neuronal activity. They are colored, they build neural activity maps and superimpose them on a T1-MRI or a three-dimensional model of the surface of the brain.
Clinical use of functional MRI. Mapping zones of brain neuronal activity allows you to plan a surgical approach and explore the pathophysiological processes of the brain. The method is used in neuropsychology in the study of cognitive functions of the brain. It is promising for the detection of foci of epilepsy.
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 adequately reflect the location of the sensorimotor, verbal and auditory zone of the cerebral cortex. Promising in the context of a single MP study in patients with brain tumors, functional MRI (as long as it is performed only for the somatosensory and visual cortex), tractography with mapping of the functionally significant cortical zone, pyramidal or visual tract, and superimposing them on a three-dimensional image of the brain. Based on the combination of the obtained data, neurosurgeons plan an operation approach and the volume of neoplasm resection, and the radiologists calculate the areas of the dose distribution of the tumor irradiation.
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