Abstract
Vascular disease is a common cause of dementia. The early diagnosis as well as the differential diagnosis of Vascular Dementia (VD) and its subtypes from other neurodegenerative causes of dementia (the most common being Alzheimer Disease) is important since they affect the therapeutic management and the outcome of patients with cognitive impairment. Functional brain imaging with Nuclear Medicine techniques, Single Photon Emission Computed Tomog raphy (SPECT) and Positron Emission Tomography (PET) play an important role in the investigation of VD. Many studies support the usefulness of these methods in the initial diagnosis, the differential diagnosis and the follow-up of VD patients. SPECT and PET are non-invasive Nuclear Medicine techniques that allow in vivo estimation of brain functions and also quantification of cerebral blood flow, cerebral blood volume, cerebral glucose metabolism and cerebral oxygen metabolism. The characteristic patterns of radiotracer distribution abnormalities as well as functional tests with the use of drugs that alter the regional Cerebral Blood Flow (rCBF) offer additional information to the other clinical, biochemical and structural imaging findings making the diagnosis of VD more accurate. The multi-infarct type of VD is characterized by multiple, asymmetric perfusion defects on brain perfusion studies. Subcortical VD is characterized by reduced perfusion but preserved oxygen extraction fraction. Bilateral temporoparietal hypoperfusion and hypometabolism characterize Alzheimer Disease. In the future, new developments will increase the sensitivity and specificity of Nuclear Medicine techniques for the detection and management of VD patients.
Keywords: Nuclear medicine, vascular dementia, Alzheimer disease