The Clinical Use of SPECT and PET Molecular Imaging in Alzheimer’s Disease

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are functional nuclear medicine techniques which allow for accurate non-invasive in vivo measurements of a wide range of regional tissue functions in man. Brain functional imaging with SPECT and PET is based on the recording of the distribution of administered radionuclides in three dimensions, thus producing maps of brain biochemical and physiological processes. SPECT and PET techniques are able to image brain perfusion and metabolism, as well as various neurotransmission or other cellular processes using specific radioligands which mark in vivo receptors, transporters or enzymes. Brain SPECT and PET imaging or molecular imaging -, has been applied to the study of Alzheimer’s disease (AD) for over two decades. These functional neuroimaging approaches have the capability of identifying subtle pathophysiologic changes in the brain before structural changes are present (Xu et al., 2000). Therefore they possess greater potential for accurate and early diagnosis, monitoring disease progression, and better treatment followup. Furthermore, the application of SPECT and PET techniques to the study of AD has led to increased understanding of the underlying pathology and the disease processes and improved the differential diagnosis from other neurodegenerative causes of dementia.