Brain structure white matter

Positron emission tomography studies using "C-toluene in nonhuman primates and mice showed a rapid uptake of radioactivity into striatal and frontal brain regions (Gerasimov et al. 2002). Maximal uptake of the radiotracer by these structures occurred 1 minutes after intravenous administration. Subsequently, clearance of the radiotracer from the striatal and frontal areas occurred rapidly, with a clearance half-life from peak uptake of 10—20 minutes. Radiotracer clearance from white matter appears to be slower... 

DTI has already been demonstrated to be effective in analyzing the internal micro structure of different tissues. For instance, orientation of nerve fiber bundles in the white matter of the brain or hollow fiber orientations in material science can be visualized using DTI [11],... 

The rate of blood flow in different structures of the brain reaches peak levels at different developmental stages, depending on the maturation rate of the particular structure. In structures that consist predominantly of white matter, the peaks coincide roughly with maximal rates of myelination. From these peaks, blood flow and, probably, cerebral metabolic rate decline to the levels characteristic of adulthood [2,39,44],... 

On the left (A) is a profile of the human brain, and on the right, a magnified view (B) of a slice through the brain as indicated by the dotted line. The anatomy of the brain consists of two hemispheres, each covered with multiple layers of important cells known as the cerebral cortex. White matter, which consists of wiring —projections from one cell to another—lies beneath the cerebral cortex, along with some groups of cells that perform various functions. The ventricles are cavities through which runs a substance called cerebrospinal fluid, which helps protect and cushion the delicate structures of the nervous system. 

Figure 4.4 General structure of the brain the central nervous system consists of the spinal cord and the brain. The brain consists of the brain stem (medulla oblongata, cerebellum, pons, mesencephalon, diencephalon) and the cerebrum (cerebral hemispheres, subcortical white matter, basal ganglia).

As part of the initial assessment of a patient with dementia, brain imaging is required. With imaging one can get information on structure or function, or a combination of the two. In AD, clinical structural MRI findings are not specific, with reports of neocortical, hippocampal, or global atrophy and white matter hyperintensities and/or associated mircovascular disease. The main reason to perform a MRI is... 

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