High-resolution in vivo imaging of human nailbed microvasculature by using photoacoustic microscopy.

Microcirculation imaging has significantly clinical value in early diagnosis and curative effect judgment of various diseases. The most superficial layer of the nailbed is rich in capillaries, which is suitable as a window on the microcirculation. However, few techniques can noninvasively observe the blood supply distribution of the nailbed, especially for high-resolution imaging of capillaries. In this study, we adapted an optical-resolution photoacoustic microscopy (OR-PAM) to image the nailbed microvasculature. The imaging sensitivity was significantly improved by hydration pretreatment of the nail. In vitro phantom experiments demonstrate that the sensitivity was improved about 3.5 times after hydration. In vivo imaging experiments of the nailbed microvasculature were conducted to further examine the enhanced sensitivity and practicability of OR-PAM. Moreover, the quantitative analysis of capillary loops showed that OR-PAM can extract the detection indicators including vascular morphology, diameter, and length, which provides a basis for clinical microcirculation detection using OR-PAM.