Imaging of the microcirculation in human skin is important for diagnosing and monitoring diseases of microvascular origin. There have been demonstrations of human skin imaging with optical based techniques, such as laser Doppler imaging, LSI and photoacoustic imaging. Although these techniques have high sensitivity to specific features of skin microvasculature, they are limited by either spatial temporal resolution or lack of depth discrimination [17
]. Recently, high resolution imaging of human skin with techniques based on OCT has been demonstrated [17
To demonstrate the capability of the IF-IDBV method, measurements were taken from human skin. Imaging was performed on a healthy adult male volunteer. The volunteer sat on a chair and held the probe himself. The imaging region was on the thigh of the volunteer [
] and the size of this region is 4 × 4 mm2. The 3D OCT data volume consisted of 4096 frames with 1024 A-lines per frame and took approximately 80 seconds to capture the entire 3D OCT data volume [-]. ~ show the MIP views of the IF-IBDV images at different depth. shows the MIP view at depths from 120 μm to 360 μm. A dense capillary network was identified. With increasing depth, larger but less dense blood vessels can be seen [, and ]. , and show, respectively, the MIP view at the depths from 360 μm to 600 μm, 600 μm to 840 μm, and 840 μm to 1300 μm. The red arrows indicate the larger blood vessels detected in the corresponding images. Clear blood vessels branches can also be found at deeper region as shown in . The red circles in - show the branch locations. It is difficult to differentiate the depth of the blood vessels from the grey scale MIP view shown in -. A color encoded depth (CED) MIP image can provide the depth information of the vessels with a single image and it can also minimize the shadowing effect. The CED MIP images for depth from 120 μm to 360 μm and depth from 360 μm to 1300 μm are shown in and .
Fig. 9 In-vivo imaging of human thigh skin. (a) The photograph shows the imaging location (white rectangle area) on the thigh of the volunteer. (b)-(e) MIP view IF-IBDV images of microcirculation network at different depths of human skin with depth of: (b) 120 (more ...)
To further demonstrate the performance of this method, we imaged the skin on a finger of a healthy volunteer [region enclosed by white line in
]. During imaging, the OCT probe was placed on a table and the forearm of the volunteer was also rested on the table. shows an OCT B-scan image of the region. - show the MIP view of the IF-IBDV images at different depths. shows one OCT image to indicate the depth region for , and . shows the MIP view at the depths from 270 μm to 450 μm. At this depth, the blood vessels manifest as dots or short lines instead of a connected network. Based on , we identify the imaged region in to be in the papillary dermis, near the dermal-epidermal junction. Hence, the dots or short lines in are the capillary loops. shows the projection view image at the depths from 450 μm to 810 μm. At this depth, a dense capillary network is visible, corresponding to the superficial horizontal plexus. In , several larger blood vessels (indicated by the red arrows) are visible. The deepest blood vessels detected are at a depth of approximately 1.2 mm. The CED MIP image for the depth from 270 μm to 1300 μm is shown in .
Fig. 10 In-vivo imaging of human finger skin. (a) The photograph shows the imaging location (area enclosed by white line) on the middle finger of the volunteer. (b) An OCT B-scan Image with the blue bars indicating the corresponding depth region for (more ...)