Abstract
Purpose :
To perform real time acquisition of subcellular dynamic signals in retinal samples using Full-Field OCT (FFOCT) for cell therapy and disease modeling applications.
Methods :
Dynamic FFOCT is a technique used to measure subcellular organelle dynamics in living cells at 3D micrometer resolution. Several issues were limiting the extensive use of dynamic FFOCT, starting with the computational load required to construct the images preventing any real time application. Here we propose a new workflow to compute images that is both faster and quantitative. The improvement in speed allows us to reach real time imaging in plane where we are able to image fluctuations in dynamics, up to 150 Hz, and tracking of subcellular organelles in retinal cells. The quantitative nature of the new methods allow us to obtain a consistent colormap where each color continuously codes for a dynamic frequency or decorrelation time that allows construction of 3D volumes and bigger ROIs by scanning samples with a raster scan pattern with color consistency. We are testing and improving our signal processing methods on primate retinal explants and human iPS-derived retinal organoids.
Results :
The dynamic image throughput reached is higher than 20 frames per second on a classic custom built computer using only a single graphics processing unit (GPU). We recorded time-lapse on retinal organoids with millisecond resolution over several hours, non invasively revealing cell development processes such as division and differentiation. Such an amount of data would not reasonably be treated in post-processing as it represents several thousands of terabytes. Live imaging in macaque retinas in 3D with 0.5 micrometers transverse resolution and 1.5 micrometers axial resolution showed retinal cellular structures in all layers including the ganglion cell, inner and outer nuclear and photoreceptor layers.
Conclusions :
The quantitative nature of the proposed method now allows dynamic image comparison, 3D reconstruction and time-lapse acquisitions without artifacts. Adding the real time feature to dynamic FFOCT is a tremendous improvement for clinical and cell biology applications as it is possible to monitor cell behavior in real time and track subcellular organelles.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.