Functional MR imaging in pediatrics.

Functional magnetic resonance (fMR) imaging can show neuronal structures underlying specific perceptual and cognitive processes. With the aid of fMR imaging, the development of brain functions can be followed, and deviation from the normal pattern can be established quickly. This article discusses the unique issues of fMR imaging in the pediatric population (e.g., the occurrence of a negative blood oxygenation-level dependent [BOLD] signal during visual stimulation in the age group in whom the synaptic density is the highest; in older children, when synaptic pruning has proceeded, the BOLD signal takes on the positive characteristics seen in adults). fMR imaging also suggests prospectively important applications in the diagnostic workup of children: an early diagnosis of functional deficit can reduce residual deficits to a minimum because remediation, such as specialized training, can be started at an early stage.