Dynamic full field optical coherence tomography: subcellular metabolic contrast revealed in tissues by interferometric signals temporal analysis

Abstract

We developed a new endogenous approach to reveal subcellular metabolic contrast in fresh ex vivo tissues taking advantage of the time dependence of the full field optical coherence tomography interferometric signals. This method reveals signals linked with local activity of the endogenous scattering elements which can reveal cells where other OCT-based techniques fail or need exogenous contrast agents. We benefit from the micrometric transverse resolution of full field OCT to image intracellular features. We used this time dependence to identify different dynamics at the millisecond scale on a wide range of organs in normal or pathological conditions.

Biodynamic imaging for phenotypic profiling of three-dimensional tissue culture

“…BDI can be related to previous work associated with dynamic measurements of cellular processes using coherence-domain techniques that include dynamic light scattering OCT, 69 fieldbased dynamic light scattering microscopy, 70 diffusion-sensitive OCT, 71 and dynamic full-field OCT. 72 BDI uses coherencedomain detection similar to each of these techniques, but with an emphasis on developing a full speckle field at tissue scales that generates a high dynamic range with high signal-to-noise per voxel. This makes it possible to differentiate subtle differences in the action of xenobiotics on tissue activity.…”

Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging

“…Interestingly, we found out that in fresh biological samples, calculating the standard deviation of the interferometric signal over time gives a substantially different contrast in comparison with the regular FF-OCT signal. We discovered later that this dynamic signal was related to cellular metabolism [39]. Interestingly, D-FF-OCT can access motility contrast in 3D, taking advantage of the FF-OCT low coherence to only select the phase variations at a given plane.…”

“…In regular FF-OCT, the temporal fluctuations are averaged out to increase the signal-to-noise ratio of strongly backscattering structures. On the contrary, in the first versions of D-FF-OCT [39], we emphasized the amplitude of fluctuations of the signal by calculating the standard deviation, as described previously. This amplitude of fluctuations not only depends on the backscattering strength, but also on the scatterers dynamics inside a given voxel.…”

“…We also developed custom-built versions of this system, exhibiting higher mechanical stability, or different cameras for example, but the general layout stays identical. We used these systems to add elastography [20,38] and motility contrasts [39,40]. It is based on a Linnik interferometer, with identical microscope objectives in both arms.…”

En face coherence microscopy [Invited]

“…Blood flow [97] can be seen and analyzed in this way and individual erythrocytes can be tracked if the frame rate of the camera is fast enough compared to the rate of flow of red blood cells [98]. Dynamic FF-OCM [99] aims to highlight another kind of motion, i.e. motion taking place inside cells and contributing to activity To extract dynamic FF-OCM signals, we record a short movie (about 1 second) of en face tomographic images and then process the time series obtained for each pixel.…”