scholarly journals Capillary stall quantification from optical coherence tomography angiogram maximum intensity projections

2021 ◽  
Author(s):  
Signe Kirk Fruekilde ◽  
Eugenio Gutiérrez Jiménez ◽  
Kim Ryun Drasbek ◽  
Christopher J Bailey
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
High Performance ◽  
Large Data ◽  
Maximum Intensity ◽  
Reproducible Research ◽  
Optical Coherence ◽  
Laptop Computer ◽  
Maximum Intensity Projections

Optical coherence tomography (OCT) is applicable to the study of cerebral microvasculature in vivo. Optimised acquisition schemes enable the generation of three-dimensional OCT angiograms, i.e., volumetric images of red blood cell flux in capillary networks, currently at a repetition rate of up to 1/10 seconds. This makes testable a new class of hypotheses that strive to bridge the gap between microscopic phenomena occurring at the spatial scale of neurons, and less invasive but crude techniques to measure macroscopic blood flow dynamics. Here we present a method for quantifying the occurrence of transient capillary stalls in OCT angiograms, i.e., events during which blood flow through a capillary branch is temporarily occluded. By making the assumption that information on such events is present predominantly in the imaging plane, we implemented a pipeline that automatically segments a network of interconnected capillaries from the maximum intensity projections (MIP) of a series of 3D angiograms. We then developed tools enabling rapid manual assessment of the binary flow status (open/stalled) of hundreds of capillary segments based on the intensity profile of each segment across time. The entire pipeline is optimized to run on a standard laptop computer, requiring no high-performance, low-availability resources, despite very large data volumes. To further reduce the threshold of adoption, and ultimately to support the development of reproducible research methods in the young field, we provide the documented code for scrutiny and re-use under a permissive open-source license.

APPLICATION OF DOPPLER OPTICAL COHERENCE TOMOGRAPHY IN RHEOLOGICAL STUDIES: BLOOD FLOW AND VESSELS MECHANICAL PROPERTIES EVALUATION

2009 ◽  
Vol 02 (04) ◽  
pp. 431-440 ◽  
Author(s):  
MARCO BONESI ◽  
ANEURIN J. KENNERLEY ◽  
IGOR MEGLINSKI ◽  
STEPHEN MATCHER
Keyword(s):  
Mechanical Properties ◽  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Early Stage ◽  
Diagnostic Technique ◽  
Feasibility Studies ◽  
Optical Coherence ◽  
Blood Flow Dynamics ◽  
Doppler Optical Coherence Tomography

Doppler Optical Coherence Tomography (DOCT) is a noninvasive optical diagnostic technique, which is well suited for the quantitative mapping of microflow velocity profiles and the analysis of flow-vessel interactions. The noninvasive imaging and quantitative analysis of blood flow in the complex-structured vascular bed is required in many biomedical applications, including those where the determination of mechanical properties of vessels or the knowledge of the mechanic interactions between the flow and the housing medium plays a key role. The change of microvessel wall elasticity could be a potential indicator of cardiovascular disease at the very early stage, whilst monitoring the blood flow dynamics and associated temporal and spatial variations in vessel's wall shear stress could help predicting the possible rupture of atherosclerotic plaques. The results of feasibility studies of application of DOCT for the evaluation of mechanical properties of elastic vessel model are presented. The technique has also been applied for imaging of sub-cranial rat blood flow in vivo.

scholarly journals 2-D Kasai velocity estimation for Doppler optical coherence tomography / by Darren Morofke.

2021 ◽  
Author(s):  
Darren Morofke
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Frequency Estimation ◽  
Doppler Frequency ◽  
Velocity Estimation ◽  
Low Flow ◽  
Invasive Technique ◽  
Optical Coherence ◽  
Detection Range

Optical Coherence Tomography (OCT) is a high-resolution, non-invasive technique to image subsurface tissue and tissue functions. A broadband light source illuminates an object and the reflected photons are processed using an interferometer, demodulated into inphase and quadrature components and then digitized. The captured data contains information about the velocity of the moving scatterers but current Doppler estimation algorithms have a limited velocity detection range. Here we demonstrate Doppler OCT (DOCT) detection of in vivo of blood flow in a rat aorta with over 1 m/s peak velocity through an esophageal DOCT probe using a new processing technique. Previous methods have used a transverse Kasai (TK) autocorrelation estimation to estimate the velocity. By calculating the Kasai autocorrelation with a lag in the depth or axial direction, backscattered frequency information is obtained. Through subtraction with stationary backscattered information, the Doppler shift is obtained by the axial Kasai (AK) technique. Maximum non-aliased Doppler frequency estimation using a time domain DOCT system increased from +/-4 kHz to =+/-1.6 MHz. The TK has better velocity resolution in the low flow rate range and when combined with the AK we demonstrate a dynamic frequency range over 100 dB with a velocity detection range from 10 [micro]m/s to over 1 m/s. This velocity range spans from microcirculation to cardiac blood flow velocities.

Real-time measurement of in-vitro and in-vivo blood flow with Fourier domain optical coherence tomography

2004 ◽  
Author(s):  
Rainer Leitgeb ◽  
Leopold Schmetterer ◽  
Wolfgang Drexler ◽  
Fatmire Berisha ◽  
Christoph K. Hitzenberger ◽  
...  
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Real Time ◽  
Time Measurement ◽  
Fourier Domain ◽  
Optical Coherence ◽  
Real Time Measurement

scholarly journals Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans

2018 ◽  
Vol 4 (12) ◽  
pp. eaav4992 ◽  
Author(s):  
Hari Ramakonar ◽  
Bryden C. Quirk ◽  
Rodney W. Kirk ◽  
Jiawen Li ◽  
Angela Jacques ◽  
...  
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Blood Vessels ◽  
Optical Coherence ◽  
Brain Hemorrhage ◽  
Biopsy Needle ◽  
Intraoperative Detection ◽  
Needle Probe ◽  
The Brain

Intracranial hemorrhage can be a devastating complication associated with needle biopsies of the brain. Hemorrhage can occur to vessels located adjacent to the biopsy needle as tissue is aspirated into the needle and removed. No intraoperative technology exists to reliably identify blood vessels that are at risk of damage. To address this problem, we developed an “imaging needle” that can visualize nearby blood vessels in real time. The imaging needle contains a miniaturized optical coherence tomography probe that allows differentiation of blood flow and tissue. In 11 patients, we were able to intraoperatively detect blood vessels (diameter, >500 μm) with a sensitivity of 91.2% and a specificity of 97.7%. This is the first reported use of an optical coherence tomography needle probe in human brain in vivo. These results suggest that imaging needles may serve as a valuable tool in a range of neurosurgical needle interventions.

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