SPECT as a diagnostic test in the investigation of dementia.

Single photon emission tomography (SPECT) permits the assessment of the decrease of regional cerebral blood flow (rCBF). The aim of this study was to assess the relationship between the different types of dementia (Alzheimer's disease (AD), vascular dementia (VaD) and frontotemporal dementia (FTD)) and the rCBF in the SPECT examination. In patients with AD, the SPECT examination showed hypoperfusion in temporoparietal regions, contrary to patients with frontotemporal dementia, where hypoperfusion was limited to the frontal area, and compared to patients with VaD, where "patchy" rCBF changes were observed in different regions. In mild cases of AD, perfusion deficits were observed in the frontal regions equal to those in VaD. The study shows that the SPECT examination may be useful in distinguishing between AD, VaD, and FTD; however, for proper diagnosis in the early stages of AD, additional factors must be taken into consideration.