[Mild cognitive impairment: imaging data]

The diagnosis of Mild Cognitive Impairment (MCI) as defined by Petersen et al. (1997), is based uniquely on clinical observations. Cerebral imaging, both morphological and functional, may in fact facilitate diagnosis, particularly with regard to the differentiation of sub-types of MCI and the identification of prodromal AD (MCI-AD). Volumetric Magnetic Resonance Imagery (MRI) examination of structures affected early in AD such as entorhinal cortex, the temporal lobe and, above all, the hippocampus, are especially useful. Hypoactivity within these regions, especially of the temporal lobe and posterior cingulate gyrus by Positon Emission Tomography, and more recently monophotonic emission tomoscintigraphy, also appears to have diagnostic utility. Studies of cholinergic system activity by functional imaging may also be of future value in MCI-AD diagnosis. MRI used in conjunction with other techniques may be of significant value, in particular the use of spectro-MRI and functional MRI. This latter technique, leading to the development of cognitive activation paradigms, is particularly promising.