Three-dimensional combined photoacoustic and optical coherence microscopy for in vivo microcirculation studies

Abstract

Photoacoustic microscopy is predominantly sensitive to optical absorption, while optical coherence tomography relies on optical backscattering. Integrating their complementary contrasts can provide comprehensive information about biological tissue. We have developed a dual-modality microscope that combines the two for studying microcirculation. Three-dimensional imaging of microvasculature and its local environment has been demonstrated at micrometer-order resolution using endogenous contrast in vivo.

Fig. 1

(Color online) Schematic of the combined photoacoustic and optical-coherence microscope. SLD: superluminescent diode. Solid lines represent single-mode optical fibers. Arrowhead solid lines show data flow. Arrowhead dashed lines show the flow of system control signals.

Fig. 2

(Color online) x-y projection images of a nude mouse ear obtained by (A) OCT and (B) PAM. (C) Overlay of (A) and (B). (D) Photograph taken through an optical microscope. SG: sebaceous gland; BV: blood vessel.

Fig. 3

(Color online) x-z cross-sectional images of a mouse ear obtained by (A) OCT and (B) PAM. (C) Overlay of (A) and (B). ED, epidermis; CT, cartilage; SG, sebaceous gland; CP, capillary.

Fig. 4

(Color online) 3D visualization of a mouse ear. (A) PAM image of the microvasculature only; (B) Dual-modality image showing the skin surface, a top view; (C) Dual-modality image showing the microvasculature in the ventral skin layer, a top view from 88 µm below the skin surface; (D) Dual-modality image showing the microvasculature in the dorsal skin layer, a top view from 148 µm below the skin surface. The micro-vessels imaged by PAM are colored in red, while avascular tissues imaged by OCT are in gray. The bounding box has dimensions of 3.6 mm × 3.6 mm × 0.4 mm.