Peritumoral oedema and lipid content.

The authors analyzed the water and lipid contents of oedematous tissues of white matter obtained during the operation, comparing with the absorption value in the CT scan. As the absorption value lowered its level, the water content increased, while the lipid decreased. However, after subtracting these two components, the content of protein also showed a significant decrement parallel to the absorption value despite the existence of extravasated protein. The decrement of lipid content was considered to be due to a dilution effect by an expanded volume of extravasated oedema fluid, as well as the decrease in protein, rather than the actual loss of tissue component; that is demyelination. It is the relative decrease in protein content which contributes to the low absorption value of oedematous tissue.