Neuroimaging findings in mild cognitive impairment

The clinical construct of mild cognitive impairment (MCI) identifi es a syndrome of cognitive defi cit without dementia, whose fate is unpredictable without an effort to establish the underlying cause. MCI is the natural “reservoir” of subsequent dementing illnesses, but it can be provoked by a variety of psychiatric and systemic diseases as well as by drugs, alcohol, and substance abuse. In this context, morphological and, especially, functional neuroimaging by means of multitracer SPECT and PET provide clue information on the underlying pathological process. Both MRI and SPECT/PET have been included as biomarkers in the revised criteria for the diagnosis of Alzheimer’s disease before dementia; similarly, dopamine transporter SPECT and FDG-PET are supportive features for the diagnosis of cognitive defi cit due to diffuse Lewy-body disease or to frontotemporal lobe degeneration, respectively. The advent of amyloid imaging with PET radiopharmaceuticals has paved the way to the noninvasive brain biopsy for beta amyloid and can detect amyloidosis in otherwise healthy individuals. In the advanced memory clinics, appropriate use of neuroimaging is nowadays the cornerstone of correct diagnosis of cognitive disorders. New developments include high-fi eld MRI equipment, new fl uorinated PET radiopharmaceuticals for amyloid detection and receptor studies, and the upcoming tool of MRI-PET.