In the present work we introduce the novel method, which allow evaluate the quantitative distribution of water molecules in brain tissue. The method is based on the labeling of water molecules by two-photon chromophore and fluorescence lifetime imaging technique (FLIM) [1-3]. FLIM allows direct visualization of the spatially dependent fluorescence decay and it is not dependent on the chromophore concentration, excitation intensity, and light-path length. Three kinds of fluids are active in a brain: cerebrospinal, extracellular, and blood. The extracellular fluid compartment includes all water and electrolytes outside of cells (interstitial fluid, plasma, and lymph); cerebrospinal fluid (CSF) mostly contained water, and formed by ultrafiltration of blood in the choroid plexus (special cells that make up the walls of some collections of arteries) [4, 5].