Ultrahigh sensitive optical microangiography for in vivo imaging of microcirculations within human skin tissue beds

Abstract

In this paper, we demonstrate for the first time that the detailed cutaneous blood flow at capillary level within dermis of human skin can be imaged by optical micro-angiography (OMAG) technique. A novel scanning protocol, i.e. fast B scan mode is used to achieve the capillary flow imaging. We employ a 1310nm system to scan the skin tissue at an imaging rate of 300 frames per second, which requires only ~5 sec to complete one 3D imaging of capillary blood flow within skin. The technique is sensitive enough to image the very slow blood flows at ~4 microm/sec. The promising results show a great potential of OMAG's role in the diagnosis, treatment and management of human skin diseases.

Fig. 1

In vivo cross sectional imaging of human skin: (A) B-scan structural image, and corresponding (B) UHS-OMAG and (C) PRODT flow images. (D) B-scan structural image, and corresponding conventional (E) OMAG and (F) PRODT flow images.

Fig. 2

Cross sectional imaging of a flow phantom in which the intralipid scattering fluid in the capillary is not flowing. (A) B-scan structural image, and corresponding (B) ultrahigh sensitive OMAG flow image, indicating the Brownian motion of particles. White bar = 500 μm.

Fig. 3

Assessment of UHS-OMAG sensitivity to the flow as compared to PRODT. (A) velocity image obtained from the flow phantom assessed by UHS-OMAG, (B) plot of the velocity data across the capillary tube at the position shown as the blue line in (A). (C) and (D) are the corresponding results obtained by PRODT imaging of the same phantom, respectively. White bar = 500 μm.

Fig. 4

(A) Schematic diagram of the blood vessel system of the human skin; (B) photograph of palm showing the scanning area (2×2 mm²); (C) 3D rendered OMAG image of blood vessels together with the 3D structures; (D) enface movie showing the imaged blood vessels at various depths (Video.mov, 1 Mbytes).

Fig. 5

UHS-OMAG provides detailed projection views of microcirculation network at different depths of skin obtained from: (A) 400 – 450μm (closely representing papillary dermis), (B) 450 – 650μm, (C) 650-780μm (closely representing reticular dermis) and (D) 780 – 1100μm (part of hypodermis), respectively. The strength of reflectance signals in the images is displayed within a range between 20dB (dark) and 50 dB (bright).