Development Of Dynamic Light Scattering Optical Coherence Tomography Methods For Detecting Cell Death

Light Scattering ◽

Exponential Decay ◽

Morphological Changes ◽

Imaging Modality ◽

Optical Coherence ◽

Cross Sectional ◽

Single Exponential

Dynamic light scattering (DLS) techniques can provide information about the quantity, size, and motion of light scatterers within a volume based on temporal fluctuations in its light scattering profile. In DLS, autocorrelation functions (ACFs) are computed from light intensity vs time signals acquired from optical imaging setups. A parameter known as the decorrelation time is computed from each ACF and is inversely related to the average motion speed of scatterers within the imaging volume. Optical coherence tomography is an imaging modality that generates 2D cross-sectional images based on light backscattered from a sample, and the combination of DLS with OCT is known as dynamic light scattering optical coherence tomography (DLS-OCT). Previously, DLS-OCT has been used to detect apoptosis, a form of programmed cell death, in non-adherent leukemia cells. Cells undergoing apoptosis experience predictable morphological changes that results in an increase in intracellular motion, and therefore a decrease in decorrelation time. We applied DLS-OCT methods to quantify the decorrelation times in adherent breast cancer cell pellets that were either untreated, treated with 20 ng/mL paclitaxel for 24 or 48 hours, or deprived of media for 24 or 48 hours. The mean decorrelation times in the paclitaxel-treated and nutrient deprived groups were significantly lower than in the untreated cells (p<0.05), suggestive of increased intracellular motion due to morphological cellular changes associated with cell death. We also investigated a new model to fit to ACFs generated by DLS-OCT of cell pellets. Typically, ACFs are fit to single exponential decay curves. We developed a model that expresses the ACFs from in vitro experiments as a sum of multiple exponential decay curves using an algorithm known as CONTIN. The curves produced by CONTIN fitted the experimental data much better than the single exponential decay fits. We speculate that the CONTIN fits, each of which resembled a superposition of three exponential decay functions, may result from light scattered from three different types of scatterers within cells, such as lysosomes, mitochondria, and nuclei.

Decorrelation Time Analysis Using Dynamic Light Scattering with Optical Coherence Tomography in an in vivo Mouse Tumour Model

10.32920/ryerson.14648115.v1 ◽

2021 ◽

Author(s):

Timothy Wan Hei Luk

Keyword(s):

Light Scattering ◽

Near Infrared ◽

Imaging Modality ◽

Preclinical Study ◽

Infrared Light ◽

Target Tissue ◽

Optical Coherence

Optical coherence tomography (OCT) is an imaging modality that uses near infrared light interferometry for non-invasive, near-histological resolution imaging at the micron level. Concepts from dynamic light scattering (DLS) can be adapted to OCT to detect and measure the motions in the target tissue. Tissue dynamics can be observed by measuring the speckle decorrelation time (DT) of the tissue. DT analysis was performed in a preclinical study to demonstrate the repeatability and feasibility of using DLS-OCT to observe mouse tumours undergoing cisplatin treatment over a 48-hour period. Differences in the average DT data were observed for control and cisplatin-injected mice. Image segmentation based on DT values was also performed to subtract the DT contributions of pixels at blood vessel locations, resulting in the improvement of average DT calculations of the tumour tissue. The results presented are a preliminary step to analyzing and monitoring tumour growth and treatment response in vivo.

Decorrelation Time Analysis Using Dynamic Light Scattering with Optical Coherence Tomography in an in vivo Mouse Tumour Model

10.32920/ryerson.14648115 ◽

2021 ◽

Author(s):

Timothy Wan Hei Luk

Keyword(s):

Light Scattering ◽

Near Infrared ◽

Imaging Modality ◽

Preclinical Study ◽

Infrared Light ◽

Target Tissue ◽

Optical Coherence

Optical coherence tomography (OCT) is an imaging modality that uses near infrared light interferometry for non-invasive, near-histological resolution imaging at the micron level. Concepts from dynamic light scattering (DLS) can be adapted to OCT to detect and measure the motions in the target tissue. Tissue dynamics can be observed by measuring the speckle decorrelation time (DT) of the tissue. DT analysis was performed in a preclinical study to demonstrate the repeatability and feasibility of using DLS-OCT to observe mouse tumours undergoing cisplatin treatment over a 48-hour period. Differences in the average DT data were observed for control and cisplatin-injected mice. Image segmentation based on DT values was also performed to subtract the DT contributions of pixels at blood vessel locations, resulting in the improvement of average DT calculations of the tumour tissue. The results presented are a preliminary step to analyzing and monitoring tumour growth and treatment response in vivo.

Assessment of cell death using dynamic light scattering with M-mode optical coherence tomography imaging

Biomedical Applications of Light Scattering X ◽

10.1117/12.2545364 ◽

2020 ◽

Author(s):

Sehar Rija ◽

Michael C. Kolios

Keyword(s):

Cell Death ◽

Light Scattering ◽

Optical Coherence Tomography Imaging

Optical Coherence ◽

Tomography Imaging ◽

Resolving directional ambiguity in dynamic light scattering-based transverse motion velocimetry in optical coherence tomography

Optics Letters ◽

10.1364/ol.39.000521 ◽

2014 ◽

Vol 39 (3) ◽

pp. 521 ◽

Cited By ~ 17

Author(s):

Brendan K. Huang ◽

Michael A. Choma

Keyword(s):

Light Scattering ◽

Transverse Motion ◽

Optical Coherence

Abstract 18844: Diagnosis of Thin-capped Fibroatheromas in Intravascular Optical Coherence Tomography Images: Effects of Light Scattering

Circulation ◽

10.1161/circ.132.suppl_3.18844 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Taylor Hoyt ◽

Jennifer Phipps ◽

Deborah Vela ◽

Tianyi Wang ◽

Maximillian Buja ◽

...

Keyword(s):

Intravascular Optical Coherence Tomography

Light Scattering ◽

Coronary Arteries ◽

Foam Cell ◽

Imaging Modality ◽

Fibrous Tissue ◽

Image Feature ◽

Optical Coherence ◽

Fibrous Cap ◽

Objectives: Intravascular optical coherence tomography (IVOCT) images are recorded by detecting light backscattered within coronary arteries. We hypothesize that non- thin-cap fibroatheroma (TCFA) etiologies may scatter light to create the false appearance of IVOCT TCFA. Background: Conflicting reports are recognized about the accuracy of IVOCT for TCFA detection. Methods: Ten human cadaver hearts were imaged with IVOCT (N=14 arteries). Coronary arteries were sectioned at 120 μm intervals. IVOCT and histologic TCFA were co-registered and compared. Results: Of 21 IVOCT TCFAs identified by two independent IVOCT core labs (fibrous cap <65 μm, lipid arc >90°), only 8 were true histologic TCFA. Foam cell infiltration was responsible for 62% of cases in which either thick-capped fibroatheromas (ThKFAs) appeared like TCFAs or arterial tissue appeared like TCFAs when no lipid core was present. Other false IVOCT TCFA etiologies included SMC-rich fibrous tissue (15%) and loose connective tissue (8%). If the lipid arc >90° criterion was disregarded, 45 IVOCT TCFAs were identified, and sensitivity of IVOCT TCFA detection increased from 53% to 88%; specificity remained high at 93%, and the presence of a new IVOCT image feature called “bright streaks” increased positive predictive value (PPV) to 53%. New mechanisms for light scattering are proposed to explain the low PPV of IVOCT to identify true TCFA (44%), and explain why other plaque components can masquerade as IVOCT TCFA. Conclusions: IVOCT can exhibit up to 88% sensitivity and 98% specificity to detect TCFA, but PPV is limited due to multiple etiologies that cause light scattering similar to true TCFA. Disregarding the lipid arc >90° IVOCT TCFA requirement, and the identification of a new feature, bright steaks, can enhance the ability of IVOCT to detect TCFA. Combining IVOCT with another imaging modality that more specifically recognizes lipid will be important for increasing PPV in the future.

Modern Trends in Imaging V: Optical Coherence Tomography for Rapid Tissue Screening and Directed Histological Sectioning

Analytical Cellular Pathology ◽

10.1155/2012/757236 ◽

2012 ◽

Vol 35 (3) ◽

pp. 129-143 ◽

Cited By ~ 11

Author(s):

Woonggyu Jung ◽

Stephen A. Boppart

Keyword(s):

Real Time ◽

Image Guidance ◽

Diagnostic Yield ◽

Imaging Modality ◽

Imaging Techniques ◽

Optical Coherence ◽

Sampling Errors ◽

Cross Sectional

In pathology, histological examination of the “gold standard” to diagnose various diseases. It has contributed significantly toward identifying the abnormalities in tissues and cells, but has inherent drawbacks when used for fast and accurate diagnosis. These limitations include the lack ofin vivoobservation in real time and sampling errors due to limited number and area coverage of tissue sections. Its diagnostic yield also varies depending on the ability of the physician and the effectiveness of any image guidance technique that may be used for tissue screening during excisional biopsy. In order to overcome these current limitations of histology-based diagnostics, there are significant needs for either complementary or alternative imaging techniques which perform non-destructive, high resolution, and rapid tissue screening. Optical coherence tomography (OCT) is an emerging imaging modality which allows real-time cross-sectional imaging with high resolutions that approach those of histology. OCT could be a very promising technique which has the potential to be used as an adjunct to histological tissue observation when it is not practical to take specimens for histological processing, when large areas of tissue need investigating, or when rapid microscopic imaging is needed. This review will describe the use of OCT as an image guidance tool for fast tissue screening and directed histological tissue sectioning in pathology.

Role of Optical Coherence Tomography on Corneal Surface Laser Ablation

Journal of Ophthalmology ◽

10.1155/2012/676740 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 11

Author(s):

Bruna V. Ventura ◽

Haroldo V. Moraes ◽

Newton Kara-Junior ◽

Marcony R. Santhiago

Keyword(s):

Laser Ablation ◽

Imaging Modality ◽

Corneal Thickness ◽

Optical Coherence ◽

Corneal Surface ◽

Cross Sectional ◽

Surface Laser ◽

The Time Domain

This paper focuses on reviewing the roles of optical coherence tomography (OCT) on corneal surface laser ablation procedures. OCT is an optical imaging modality that uses low-coherence interferometry to provide noninvasive cross-sectional imaging of tissue microstructurein vivo.There are two types of OCTs, each with transverse and axial spatial resolutions of a few micrometers: the time-domain and the fourier-domain OCTs. Both have been increasingly used by refractive surgeons and have specific advantages. Which of the current imaging instruments is a better choice depends on the specific application. In laserin situkeratomileusis (LASIK) and in excimer laser phototherapeutic keratectomy (PTK), OCT can be used to assess corneal characteristics and guide treatment decisions. OCT accurately measures central corneal thickness, evaluates the regularity of LASIK flaps, and quantifies flap and residual stromal bed thickness. When evaluating the ablation depth accuracy by subtracting preoperative from postoperative measurements, OCT pachymetry correlates well with laser ablation settings. In addition, OCT can be used to provide precise information on the morphology and depth of corneal pathologic abnormalities, such as corneal degenerations, dystrophies, and opacities, correlating with histopathologic findings.