Numerical study of the feasibility of scanning hematoma and blood vessels in the human brain

We study theoretically the problem of sensitivity of frequency modulated reflectance to the inclusion of either a hematoma, modeled as a large slab, or a blood vessel, modeled as a straight tube, in semi-infinite human tissue systems. We use two different numerical techniques: (1) numerical integration of three-dimensional diffusion equation; and (2) Monte Carlo simulations with a biasing technique. We find that inclusion of a hematoma slab or a blood vessel cylinder gives rise to significant change in both the phase and modulation as compared to a homogeneous medium. The reflected signals from these two situations are also significantly different which may allow differentiation between the two objects. In the particular case of imbedded cylindrical blood vessel we find that up to a depth of z equals 25 mm it is possible to use the phase shift or modulation change of reflected photon flux at different locations on the sample surface to determine the direction, size, and depth of the embedded blood vessel, provided phase change sensitivity of 0.1 deg or modulation change sensitivity 0.01 are available.