Hematocrit dependence of flow signal in optical coherence tomography angiography

Yang, Jianlong; Su, Johnny P.; Wang, Jie; Men, Silu; Jia, Yali; Huang, David; Liu, Gangjun

doi:10.1364/boe.8.000776

Cited by 19 publications

(14 citation statements)

References 35 publications

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“…In this regard, the identification of intra- and extra-ocular factors, which affect blood flow properties and thus OCTA measurements is of central interest. [4–10] We have recently reported that OCTA measurements can be altered by a physical exercise intervention. After a controlled short term (4-weeks) high-intensity interval training period, FDsM and FDnhPP values were changed and a strong effect on the FAZ area was observed, which was reduced by ~ 14%.…”

Section: Discussionmentioning

confidence: 99%

“…A significant effect of haematocrit on the decorrelation signal using 45%, 40% and 32% haematocrit blood samples has been described in an ex-vivo model. [4] In our study, haematocrit values were determined in twelve randomly selected participants without significant differences in haematocrit values. However, this sample may not allow to fully exclude any effects of the haematocrit in our study.…”

Section: Discussionmentioning

confidence: 99%

“…Since OCTA algorithms detect blood flow based on the OCT signal scattered or reflected by moving red blood cells, one important parameter recently reported by Yang and colleagues is the hematocrit level, which significantly affects the flow signal particularly in narrow capillary vessels localized in the macula or at the optic nerve head (ONH). [4] Intraocular pressure change is an example of an intraocular parameter that influences peripapillary flow density (FD) in OCTA. [5] Other transient systemic factors, such as changes in oxygenation may also have a significant impact on FD measurements.…”

Section: Introductionmentioning

confidence: 99%

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Correlation analysis of physical fitness and retinal microvasculature by OCT angiography in healthy adults

Nelis¹,

Schmitz²,

Klose³

et al. 2019

PLoS ONE

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Optical coherence tomography angiography (OCT-A) represents the most recent modality in retinal imaging for non-invasive and depth-selective visualization of blood flow in retinal vessels. With regard to quantitative OCTA measurements for early detection of subclinical alterations, it is of great interest, which intra- and extra-ocular factors affect the results of OCTA measurements. Here, we performed OCTA imaging of the central retina in 65 eyes of 65 young healthy female and male participants and evaluated individual physical fitness levels by standard lactate diagnostic using an incremental maximal performance running test. The main finding was that OCTA measurements of the foveal avascular zone (FAZ) area were associated with physical fitness. Using multivariate regression analysis, we found that running speed at the individual lactate threshold, a marker strongly associated with aerobic performance capacity, significantly contributed to differences in FAZ area (β = 0.111, p = 0.032). The data indicates that smaller FAZ areas are likely observed in individuals with higher aerobic exercise capacity. Our findings are also of interest with respect to the potential use of retinal OCTA imaging to detect exercise-induced microvascular adaptations in future studies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Correlation analysis of physical fitness and retinal microvasculature by OCT angiography in healthy adults

Nelis¹,

Schmitz²,

Klose³

et al. 2019

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…This requires a longer enough time interval between adjacent repeated B‐scans and enough number of repetitions at the same B‐scan location. We found that the optimum time interval was 5 ms when only two B‐scan at the same location was used . So in this study, we set the B‐scan time interval to 5 ms for widefield imaging to keep the sensitivity.…”

Section: Discussionmentioning

confidence: 99%

Extended axial imaging range, widefield swept source optical coherence tomography angiography

Liu

Yang

Wang

et al. 2017

Journal of Biophotonics

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We developed a high-speed, swept source OCT system for widefield OCT angiography (OCTA) imaging. The system has an extended axial imaging range of 6.6 mm. An electrical lens is used for fast, automatic focusing. The recently developed split-spectrum amplitude and phase-gradient angiography allow high-resolution OCTA imaging with only two B-scan repetitions. An improved post-processing algorithm effectively removed trigger jitter artifacts and reduced noise in the flow signal. We demonstrated high contrast 3mm×3mm OCTA image with 400×400 pixels acquired in 3 seconds and high-definition 8mm×6mm and 12mm×6mm OCTA images with 850×400 pixels obtained in 4 seconds. A widefield 8mm×11mm OCTA image is produced by montaging two 8mm×6mm scans. An ultra-widefield (with a maximum of 22 mm along both vertical and horizontal directions) capillary-resolution OCTA image is obtained by montaging six 12mm×6mm scans.

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“…The model was calibrated using a laboratory phantom that used ex vivo human blood flowing through a microfluidic chip. 12 , 13 …”

Section: Methodsmentioning

confidence: 99%

Enhanced Quantification of Retinal Perfusion by Improved Discrimination of Blood Flow From Bulk Motion Signal in OCTA

Camino

Zhang

Liu

et al. 2018

Trans. Vis. Sci. Tech.

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PurposeQuantification of optical coherence tomography angiography (OCTA) is confounded by the prevalence of bulk motion. We have previously developed a regression-based bulk motion subtraction (rb-BMS) algorithm that estimates bulk motion velocity and corrects for its effect on flow signal. Here, we aim to investigate its ability to improve the reliability of capillary density (CD) quantification.MethodsTwo spectral-domain systems (70-kHz Avanti/AngioVue and 68-kHz Cirrus/AngioPlex) acquired 6 × 6-mm OCTA scans. The rb-BMS algorithm was applied on each OCTA volume. Regression analysis of angiographic versus reflectance signal of avascular A-lines in B-frames was used to set an optimized reflectance-adjusted threshold for discriminating vascular versus nonvascular voxels. The CD was calculated from en face maximum projections of the superficial vascular complex in macular scans and the nerve fiber layer plexus in disc scans, excluding large vessels. The retinal signal strength (RSS) was calculated by averaging the logarithmic-scale OCT reflectance signal, and its correlation with CD was investigated.ResultsEight healthy eyes were scanned with each instrument on 2 separate days. The rb-BMS algorithm improved within-visit repeatability and between-visit reproducibility of CD compared with a global-threshold measurement algorithm. Using the rb-BMS algorithm, the CD results were less affected by RSS and the population variation was reduced. Motion-induced line artifacts were also reduced.ConclusionsThe rb-BMS algorithm improved the reliability of perfusion quantification in OCTA on both Food and Drug Administration–cleared spectral-domain OCTA systems.Translational RelevanceThe rb-BMS method helped reduce the inter-scan variability by generating accurate vessel maps, improving the reliability of retinal perfusion quantification.

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Hematocrit dependence of flow signal in optical coherence tomography angiography

Cited by 19 publications

References 35 publications

Correlation analysis of physical fitness and retinal microvasculature by OCT angiography in healthy adults

Correlation analysis of physical fitness and retinal microvasculature by OCT angiography in healthy adults

Extended axial imaging range, widefield swept source optical coherence tomography angiography

Enhanced Quantification of Retinal Perfusion by Improved Discrimination of Blood Flow From Bulk Motion Signal in OCTA

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