Clinical challenges of functional MRI

Functional magnetic resonance imaging (fMRI) has revolutionized clinical brain mapping by allowing relatively rapid and noninvasive assessment of brain activity. Because of its relative ease, it has become the predominant functional neuroimaging technique since its original report by Belliveau et al. [1]. The appeal of fMRI is attributable to several advantages that it offers over other functional neuroimaging techniques. Perhaps the most important advantages, especially in clinical populations, relate to the safety of fMRI: it is noninvasive, in contrast to either the Wada test or electrical stimulation mapping, and does not require exposure to ionizing radiation (as with positron emission tomography [PET]). The other major advantage of fMRI is that it offers the opportunity for reliable, repeated measurements of the same task to investigate response consistency, to compare activations across tasks, and to measure change over time. Above all, fMRI is sufficiently powerful to produce maps of cognitive and motor functions that are reliable and valid at the single-subject level.