Three-dimensional optical imaging of microvascular networks within intact lymph node in vivo

Abstract

Sentinel lymph nodes (SLNs) are the first lymph nodes to drain wastes originated from cancerous tissue. There is a need for an in vivo imaging method that can image the intact SLN to further our understanding of its normal as well as abnormal functions. We report the use of ultrahigh sensitive optical microangiography (UHS-OMAG) to image functional microvascular and lymphatic vessel networks that innervate the intact lymph node in mice in vivo. The promising results show a potential role of UHS-OMAG in the future understanding and diagnosis of the SLN involvement in cancer development.

Figure 1

UHS-OMAG images of depth-resolved microstructures and microcirculation network within an axillary lymph node in vivo. The insert in the upper left corner in (c) is the photograph of the sample in which a bean-shaped axillary lymph node is situated, where the white box indicates the region scanned by OMAG. The top images show (a) a typical cross sectional microstructure and (b) the corresponding blood flow images at the location indicated by the dashed line in the photograph. The bottom images show the enface images of (c) the microstructures and (d) the corresponding blood vessels, extracted from the 3-D optical dataset. The results show the morphological features as well as the microvascular network within the lymph node. (scale bar=500 μm).

Figure 2

UHS-OMAG visualizes 3-D morphology and microvascular network within an axillary lymph node. Shown are (a) the merged view of volumetric microstructures and blood vessels, where a cut-away view of the microstructural volume gives an appreciation of how blood vessels innervate this lymphatic tissue; (b) the volumetric visualization of the blood vessel network alone; and (c) the x-y projection view of the blood vessels shown in (b). The volume size is 2.0×2.0×1.5 mm³ (x-y-z) in (a) and (b).

Figure 3

UHS-OMAG has the potential to identify both the vasculatures and lymphatic vessels within axillary lymph nodes, without the need of a contrast agent. (a) and (b) show the enface structural images of lymph node at depths of ∼200 and ∼400 μm, respectively. (Scale bar: 500 μm). (d) is a cross sectional image of microstructures taken at the location indicated by the white line in (b), where the black hole is assumed to be a lymphatic vessel, and (c) shows the profile of optical scattering strength from top to bottom, as indicated by the line. (e) gives the 3-D view of the merged vasculature and lymphatic vessels (green color). The volume size is 2.0×2.0×1.5 mm³ (x-y-z). (Color online only.)