Fundamental study for optical imaging of arteriovenous fistula: 2 Detection of blood vessel diameter change using point spread function

Frequent maintenance for the arteriovenous fistula for hemodialysis is essential, since it often causes stenosis and occlusion. We have developed a simple and noninvasive technique to obtain transillumination images of the arteriovenous fistula using near-infrared light. However, the image of the blood vessel is significantly blurred due to the strong scattering in the body tissue. To solve this problem, we applied the deconvolution technique with a point spread function. In the experiment using the human forearm phantom, we attempted to detect the diameter change of the blood-filled tube. As a result, we could detect the diameter change within 0.5 mm accuracy at 1 mm depth from the body surface. This suggests that we can detect the temporal change of the arteriovenous fistula and that this enables us the daily monitoring of its condition.