Feasibility of intracranial near-infrared optical scanning.

Light injected at a point on a surface of a scattering medium is emitted at the surface after traveling a quasisemicircular path deep into the medium. This phenomenon can be exploited to detect objects immersed in the medium from time-resolved measurements of light intensity at the surface. Our experiments on model systems demonstrate that absorbing objects, surrounded by bone and other scattering material, can be detected. The technique yields surface images of absorbing objects submerged in a scattering medium. Images of the same phantoms inside the cavity of a skull can be obtained by the same technique.