Miniaturized Photoacoustic Probe for Imaging of Subcutaneous Microvessels Within Human Skin

Background: Subcutaneous microvascular visualization is important for accurate diagnosis and precise treatment of those diseases that are associated with subcutaneous microangiopathy. Pure optical imaging technology and ultrasound imaging technology are commonly used to observe subcutaneous blood vessels non-invasively. However, pure optical imaging is limited to visualizing superficial skin features due to the strong scattering of light by biological tissues, while ultrasound imaging which can detect deep tissues has poor resolution and low contrast to reveal microvascular networks. This results in a lack of intuitive understanding of the disease lesion.

Methods: A miniaturized photoacoustic (PA) probe, which is capable of imaging subcutaneous microvessels with high resolution and deep penetration, was built in this work. The probe is small enough to be hand-held and takes 16 seconds to obtain a maximum amplitude projection image of 400×400 pixels with the imaging area of 2×2 mm.

Results: The miniaturized PA probe was measured to have a lateral resolution of about 8.9 µm and an imaging depth of about 2.4 mm. Besides, animal experiments and human skin imaging have been implemented. The results show that the miniaturized PA probe not only visualizes the subcutaneous microvessels, but also obtains quantitative information such as the diameters and the depths of blood vessels.

Conclusions: The miniaturized PA probe has potential been used into clinic, and providing quantitative blood vessel information for the diagnosis and monitoring of vascular diseases.