4 research outputs found
Label-free intratissue activity imaging of alveolar organoids with dynamic optical coherence tomography
An organoid is a three-dimensional (3D) in vitro cell culture emulating human
organs. We applied 3D dynamic optical coherence tomography (DOCT) to visualize
the intratissue and intracellular activities of human induced pluripotent stem
cells (hiPSCs)-derived alveolar organoids in normal and fibrosis models. 3D
DOCT data were acquired with an 840-nm spectral domain optical coherence
tomography with axial and lateral resolutions of 3.8 {\mu}m (in tissue) and 4.9
{\mu}m, respectively. The DOCT images were obtained by the
logarithmic-intensity-variance (LIV) algorithm, which is sensitive to the
signal fluctuation magnitude. The LIV images revealed cystic structures
surrounded by high-LIV borders and mesh-like structures with low LIV. The
former may be alveoli with a highly dynamics epithelium, while the latter may
be fibroblasts. The LIV images also demonstrated the abnormal repair of the
alveolar epithelium
Label-free metabolic imaging of non-alcoholic-fatty-liver-disease (NAFLD) liver by volumetric dynamic optical coherence tomography
Label-free metabolic imaging of non-alcoholic fatty liver disease (NAFLD)
mouse liver is demonstrated ex vivo by dynamic optical coherence tomography
(OCT). The NAFLD mouse is a methionine choline-deficient (MCD)-diet model, and
two mice fed MCD diet for 1 and 2 weeks are involved in addition to a
normal-diet mouse. The dynamic OCT is based on repeating raster scan and
logarithmic intensity variance (LIV) analysis which enables volumetric
metabolic imaging with a standard-speed (50,000 A-lines/s) OCT system.
Metabolic domains associated with lipid droplet accumulation and inflammation
are clearly visualized three-dimensionally. Particularly, the normal-diet liver
exhibits highly metabolic vessel-like structures of peri-vascular hepatic
zones. The 1-week MCD-diet liver shows ring-shaped highly metabolic structures
formed with lipid droplets. The 2-week MCD-diet liver exhibits fragmented
vessel-like structures associated with inflammation. These results imply that
volumetric LIV imaging is useful for visualizing and assessing NAFLD
abnormalities
Theoretical model for en face optical coherence tomography imaging and its application to volumetric differential contrast imaging
A new formulation of lateral imaging process of point-scanning optical
coherence tomography (OCT) and a new differential contrast method designed by
using this formulation are presented. The formulation is based on a
mathematical sample model called the dispersed scatterer model (DSM), in which
the sample is represented as a material with a spatially slowly varying
refractive index and randomly distributed scatterers embedded in the material.
It is shown that the formulation represents a meaningful OCT image and speckle
as two independent mathematical quantities. The new differential contrast
method is based on complex signal processing of OCT images, and the physical
and numerical imaging processes of this method are jointly formulated using the
same theoretical strategy as in the case of OCT. The formula shows that the
method provides a spatially differential image of the sample structure. This
differential imaging method is validated by measuring in vivo and in vitro
samples
Label-free visualization and quantification of the drug-type-dependent response of tumor spheroids by dynamic optical coherence tomography
Abstract We demonstrate label-free dynamic optical coherence tomography (D-OCT)-based visualization and quantitative assessment of patterns of tumor spheroid response to three anti-cancer drugs. The study involved treating human breast adenocarcinoma (MCF-7 cell-line) with paclitaxel (PTX), tamoxifen citrate (TAM), and doxorubicin (DOX) at concentrations of 0 (control), 0.1, 1, and 10 µM for 1, 3, and 6 days. In addition, fluorescence microscopy imaging was performed for reference. The D-OCT imaging was performed using a custom-built OCT device. Two algorithms, namely logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDS l ) were used to visualize the tissue dynamics. The spheroids treated with 0.1 and 1 µM TAM appeared similar to the control spheroid, whereas those treated with 10 µM TAM had significant structural corruption and decreasing LIV and OCDS l over treatment time. The spheroids treated with PTX had decreasing volumes and decrease of LIV and OCDS l signals over time at most PTX concentrations. The spheroids treated with DOX had decreasing and increasing volumes over time at DOX concentrations of 1 and 10 µM, respectively. Meanwhile, the LIV and OCDS l signals decreased over treatment time at all DOX concentrations. The D-OCT, particularly OCDS l , patterns were consistent with the fluorescence microscopic patterns. The diversity in the structural and D-OCT results among the drug types and among the concentrations are explained by the mechanisms of the drugs. The presented results suggest that D-OCT is useful for evaluating the difference in the tumor spheroid response to different drugs and it can be a useful tool for anti-cancer drug testing