Imaging of venous valves with photoacoustics

摘要

We report results of a feasibility study regarding the question whether or not venous valves can be imaged using photoacoustics, and how they will appear in the images. First an in vitro study was made on tissue phantoms consisting of blood filled rubber tubes with discontinuities in the inner tube wall. We also have studied superficial veins on the ventral side of the wrist. For excitation, an Nd:YAG laser at 1064 nm was used. Detection of acoustic signals was performed with a PVdF sensor consisting of two concentric rings. Measurements were performed on valves which where first localized by palpation. The phantom studies showed that irregular structures of the tube walls could clearly be identified from the photoacoustic images. Furthermore, in a photoacoustic image of a vein at the dorsal side of the wrist, the presence of a valve could be identified from a region of increased signal intensity within the vessel lumen.