[Image analysis in patients with dementia].
There are a number of noninvasive imaging methods in patients with dementia, including X-ray CT, MRI, SPECT and PET. Anatomical imaging using CT and MRI is often used for assessing severity of brain atrophy, which is commonly seen in patients with dementia. However, the early detection of brain abnormalities seem to be limited with these methods. Brain functional studies using radionuclide techniques have been recently developed with introduction of a variety of new radiopharmaceuticals. Among them, brain perfusion SPECT which is clinically available in most of the hospitals, is considered as a powerful means for accurate diagnosis and assessment of severity of dementia. Hypoperfusion is commonly seen in bilateral parieto-temporal cortex (association cortex) in patients with Alzheimer's disease. Frontal hypoperfusion is seen in the advanced cases of Alzheimer's disease. This disease is easily differentiated with multi-infarct dementia where multiple asymmetrical hypoperfusion is seen in the brain cortex on SPECT. More importantly, such functional abnormality is often observed in patients with normal findings in CT or MRI, indicating clinical value of brain perfusion SPECT for early detection of Alzheimer's disease. Bilateral hypoperfusion is noted in the frontal cortex in patients with Pick disease. Recently biochemical imaging can be obtained with positron emission tomography (PET) using various physiological tracers labeled with C-11, N-13, O-15, and F-18. Cerebral perfusion, metabolism and receptor functions can be quantitatively measured in vivo. The PET study nicely demonstrated that hypometabolism in bilateral parieto-temporal cortex in patients with Alzheimer's disease. Furthermore, glucose metabolism is considered to be further suppressed compared to perfusion, indicating suppression of brain synaptic function in this disease. In conclusion, brain functional imaging using SPECT and PET is useful for the detection and evaluation of a variety of dementia.
Tamaki
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Department of Nuclear Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
D001921:Brain / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D003704:Dementia / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D014055:Tomography, Emission-Computed; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed