Visual appearance of blood vessels: a phantom study

The blue appearance of veins has been addressed in previous studies; however, an experimental demonstration that reproduces this phenomenon with comprehensible optical properties has not yet been achieved. To address this gap, silicone-based skin phantoms were fabricated to replicate the optical properties of human skin. Cylindrical vessel inclusions of varying depths and diameters were incorporated into the phantoms and filled with silicone mimicking blood at different oxygenation states. The vessels' appearance was quantitatively evaluated using calibrated photography and hyperspectral imaging. Monte Carlo light transport simulations were employed to support the experimental findings. The phantoms with venous inclusions exhibited the characteristic blue hue of veins, thus demonstrating that vein blueness does not arise solely from blood's intrinsic absorption but from the complex interplay of tissue optics and visual perception. These experimental findings support our previously proposed theory.