Application of phase variance optical coherence tomography for in-vivo imaging of retinal micro-vasculature in mice

Abstract

 

Purpose

 

To evaluate feasibility of phase variance optical coherence tomography (pv-OCT) for in-vivo visualization of a retinal blood perfusion maps in mice.

 

Methods

 

High acquisition speed Fourier-domain OCT (Fd-OCT) (132nm @ 855nm broadband light source (Superlum) and CMOS camera (Basler) operating at 125,000 A-scan/s) was used to acquire in vivo mouse retinal volumetric data sets. Wild Type mice and models of retinal vascular development were imaged with Color Fundus and Fundus Fluorescein Angiography (Micron III, Phoenix Research Lab.). PV-OCT volumetric scanning patterns include acquisition of several B-scans over the same location (M-scans). After acquiring these data sets intensity and phase information of each set of M-scans were used to calculate OCT signal phase variance using software developed by Caltech Biological Imaging Center. Several scanning schemes, for instance with sampling densities (3μm or 1.5μm) or scanning areas (1x1mm2 or 0.5x5.5mm2), were used while the total volume acquisition time was kept below 5 seconds to reduce motion artifacts. The phase variance processing allows clear visualization of blood cell movement within the retina vasculature. En face projection images created from the three-dimensional data sets provide clear vascular visualization comparable to currently used invasive angiographic imaging. During the imaging mice were anesthetized with general anesthesia using 2% inhalational anesthetic: isoflurane.

 

Results

 

In vivo mice ocular vasculature images of Wilde type mice and models of retinal vascular development were reconstructed using the phase variance method in the retina. The demonstrated images show 3D reconstruction of the intensity of the OCT data set and corresponding projection view of pvOCT over the scanning area, 1x1mm2, in the retinal layers. The en face images of pvOCT and FA are used for comparison of the retinal vascular network. (Not included in this abstract).

 

Conclusions

 

Phase variance OCT due to depth sectioning can be used to visualize two-dimensional ocular vessel networks within well-defined retinal or layers. This should be beneficial for non-invasive in-vivo monitoring of volumetric morphology of retinal vasculature in animal models of vascular development or disease.

 

 

Volumetric visualization of the in-vivo mice OCT data.

 

 

Projection view of pvOCT in the retinal layers over the scanning area, 1x1mm².

 

Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 551 imaging/image analysis: non-clinical • 688 retina