About
80% of brain water is found inside the cells and a large fraction of it is
interfacial water with properties substantially different from those of bulk
water. Evidence for a large osmotically unresponsive compartment, available
from literature, is substantiated by the finding that a very large fraction of
brain water does not contribute to its electrical conductivity. This is
determined by investigating the correlation between conductivity and water
content in tumour patients in vivo. More than 80% of brain water is found to be
unresponsive, with variations reflecting tissue and tumour type. This work
describes a noninvasive method for the characterisation of a deeply microscopic
parameter of the living tissue.