Improvement of transcutaneous fluorescent images with a depth-dependent point-spread function.

The point-spread function (PSF) for transcutaneous fluorescent imaging was obtained as an analytical solution in a closed form. It is applicable to cases in which the optical property of the image-blurring turbid medium is considered to be fairly homogeneous. We proposed a technique to improve a transcutaneous image by using depth-dependent PSF. Contrast of the fluorescent image was improved for depths of 1-15 mm in a scattering medium (micro(s)' = 1/mm). The visible depth was more than doubled with this technique. An experiment with a rat demonstrated considerable improvement of a transcutaneous image of the cerebral vein at a specified depth. The spread image of the heart was reduced to the correct size by use of the PSF with the actual depth of the heart.