Neuroimaging on Dementia(Recent Progress in Alzheimer Disease Research)

Neuroimaging for diagnosis of dementia is becoming clinically important and includes computed tomography (CT) , magnetic resonance imaging (MRI) , single photon emission tomography (SPECT) , and positron emission tomography (PET) . Treatable and reversible dementias should be excluded before making diagnosis of Alzheimer type dementia, or other neurodegenerative diseases causing dementia. MRI is the most frequently used and helpful imaging modality for diagnosis of dementia. Secondary dementias detectable with MRI are cerebrovascular diseases, brain tumors, hydrocephalus, demyelinating diseases, inflammatory and infectious diseases. Diffusion - weighted MR imaging is sensitive for herpes encephalitis and Creutzfeldt - Jakob disease that could be hardly detected with conventional pulse sequences in the early stage of the diseases. MRI features for diagnosis of Alzheimer type dementia have been evaluated visually to detect atrophy of the hippocampus and surrounding medial temporal region, but it is very difficult for elderly patients to differentiate pathologic atrophy from physiologic atrophy with aging. Recently the voxel - based specific regional analysis system for Alzheimer's disease (VSRAD) has been introduced for the diagnosis of Alzheimer type dementia with MRI. In this paper, the role of CT and MRI for diagnosis of treatable and reversible dementias is mentioned, and implementation and some clinical issues of VSRAD are discussed