Density brain tissues

CBV can be calculated from (5.4) if one takes into account the brain tissue density, p, and a correction factor, CH, to adjust the difference between arterial and capillaiy hematocrit [70,116]. In vivo experiments in the 1970s demonstrated the markedly lower hematocrit in capillaries compared to arterial hematocrit [117-119] hence the introduction of the CH is required for the quantification of CBV as follows ... 

Occasionally, the diagnosis of acute ischemia can be established by NCCT because embohc material can be visualized directly, usually in the MCA or its branches. Emboli are often more radiodense than normal brain tissue, and therefore an affected proximal MCA may appear as a linear hyperdensity ( hyperdense middle cerebral artery sign or HMCA sign, Fig. 2.1c). One study found that the HMCA sign was 100% specific for MCA occlusion, but only 27% sensitive, probably because the density of embohc material is often indistinguishable from that of the normal MCA. ... 

These results led us to analyze the relationship between carrier-wave frequency and power density. We developed a mathematical model (6) which takes into account the changes in complex permittivity of brain tissue with frequency. This model predicted that a given electric-field intensity within a brain-tissue sample occurred at different exposure levels for 50-, 147-, and 450-MHz radiation. Using the calculated electric-field intensities in the sample as the independent variable, the model demonstrated that the RF-induced calcium-ion efflux results at one carrier frequency corresponded to those at the other frequencies for both positive and negative findings. In this paper, we present two additional experiments using 147-MHz radiation which further test both negative and positive predictions of this model. 

E. Lampe, J. A. Faulk, J. M. Induction of calcium-ion efflux from brain tissue by radio frequency radiation Effect of sample number and modulation frequency on the power-density window. Bioelectromagnetics, 1980, 1,... 

Blackman, C. F. Benane, S. G. Joines, W. T. Hollis, M. A. House, D. E. Calcium-ion efflux from brain tissue Power density vs. internal field intensity dependencies at 50-MHz RF radiation. Bioelectromagnetics, 1980, 1.(3). 

By two dimensional (2D) imaging of brain tissues, a defined sample area (several cm ) of a thin section of brain tissue (thickness 20(j,m) was ablated hue by line with a focused laser beam in a cooled laser ablation chamber (using two Peltier elements behind the target holder made of aluminium). The spot size of the laser beams was about 50(xm, the laser power density 3 x 10 Wcm . Ion intensities of the analytes, e.g., P+, Cu or Zn , were... 

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