Impact of Multiple En Face Image Averaging on Quantitative Assessment from Optical Coherence Tomography Angiography Images

Uji, Akihito; Balasubramanian, Siva; Lei, Jianqin; Baghdasaryan, Elmira; Al-Sheikh, Mayss; Sadda, Srinivas R.

doi:10.1016/j.ophtha.2017.02.006

Cited by 155 publications

(168 citation statements)

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“…Third, although AS-OCTA images were successfully acquired, they still had significant noise. Multiple image averaging is known to be helpful in improving image quality in posterior-segment OCTA 27 and AS-OCT, 43, 44 as well as posterior-segment OCT 45 . AS-OCTA imaging with multiple image averaging might be a possible method to improve the image quality in future studies.…”

Section: Discussionmentioning

confidence: 99%

“…For measurements, a 1024 × 1024-pixel rectangular box was cropped and binarized using a modified version of the previously reported method using ImageJ software (Wayne Rasband, National Institutes of Health, Bethesda, MD; available at http://rsb.info.nih.gov/ij/index.html) (Supplemental Figure 1). 26, 27 Briefly, after processing with a top-hat filter, images were skeletonized by processing the OCTA images through a band-pass filter. This was followed by binarization with intensity thresholding using Otsu’s thresholding method for automatic binarization-level decisions.…”

Section: Quantitative Measurementsmentioning

confidence: 99%

“…26, 27, 29 Vessel diameter index, which represents the average vessel caliber, was calculated by dividing the total vessel area in the binarized image (shown in Supplemental Figure 1, Middle) by the total vessel length in the skeletonized image (shown in Supplemental Figure 1, Right). 21, 27 Fractal dimension was calculated on the skeletonized image using ImageJ plugin software. 27, 30 The box-counting method was used for calculation.…”

Section: Quantitative Measurementsmentioning

confidence: 99%

“…21, 27 Fractal dimension was calculated on the skeletonized image using ImageJ plugin software. 27, 30 The box-counting method was used for calculation. Fractal dimension could range from 0 to 2, and images with a more complex vessel branching pattern will have a higher fractal dimension.…”

Section: Quantitative Measurementsmentioning

confidence: 99%

See 3 more Smart Citations

Conjunctival and Intrascleral Vasculatures Assessed Using Anterior Segment Optical Coherence Tomography Angiography in Normal Eyes

Akagi

Uji

Huang

et al. 2018

American Journal of Ophthalmology

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Section: Discussionmentioning

confidence: 99%

Section: Quantitative Measurementsmentioning

confidence: 99%

Section: Quantitative Measurementsmentioning

confidence: 99%

Section: Quantitative Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Conjunctival and Intrascleral Vasculatures Assessed Using Anterior Segment Optical Coherence Tomography Angiography in Normal Eyes

Akagi

Uji

Huang

et al. 2018

American Journal of Ophthalmology

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“…The results from this study may not be generalisable to older subjects with media opacity, reduced vision or unstable fixation, particularly given the recent report suggesting the need for averaging a greater number of B‐scans in the presence of media opacity to improve image quality of retinal OCT images . Further, the optimum number of B‐scans required for averaging may vary for determination of the thickness of different vascular layers of the choroid, given the potential confounding effect of background noise on the threshold levels for binarization techniques that are often used in these measurements …”

Section: Discussionmentioning

confidence: 90%

Impact of image averaging on wide‐field choroidal thickness measurements using enhanced‐depth imaging optical coherence tomography

Hoseini-Yazdi

Vincent

Collins

et al. 2019

Clinical and Experimental Optometry

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Background: The aim of this study was to examine the influence of B-scan averaging on choroidal thickness using wide-field enhanced-depth imaging optical coherence tomography. Methods: Six high-resolution trans-foveal horizontal enhanced-depth imaging line scans (spanning a 60 field) were acquired consecutively from the right eye of 10 healthy adults (mean age 30 AE 5 years), with each line scan an average of 10, 20, 30, 40, 50 or 100 B-scans, using the automated real-time image averaging and follow-up features of a Spectralis device. The impact of B-scan averaging on regional measures of wide-field choroidal thickness (across macular and peripheral regions) and their accuracy was investigated, assuming that averaging 100 B-scans would provide the most accurate estimate of choroidal thickness. Results: Regional estimates of wide-field choroidal thickness did not vary across the different B-scan averaging conditions (all p > 0.05). The mean choroidal thickness averaged across the full wide-field area exhibited the closest agreement to measures obtained with 100 averaged B-scans, when frame averaging exceeded 30 B-scans (95 per cent limits of agreement +10 to −7, +7 to −7 and +6 to −3 μm for 30, 40 and 50 averaged B-scans, respectively), compared to 10 and 20 averaged B-scans (95 per cent limits of agreement +13 to −8 and +13 to −6 μm, respectively; p < 0.01 and p < 0.02 compared to the accuracy of 50 averaged B-scans). Conclusion: Averaging 30 B-scans for an individual enhanced-depth imaging optical coherence tomography line scan provided accurate measures of choroidal thickness across a wide-field (60 ) area in young healthy eyes. This information can assist in designing the volumetric scan protocols required for detailed examination of the macular and peripheral choroid.

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Choriocapillaris Imaging Using Multiple En Face Optical Coherence Tomography Angiography Image Averaging

et al. 2017

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Imaging of the choriocapillaris in vivo is challenging with existing technology. Optical coherence tomography angiography (OCTA), if optimized, could make the imaging less challenging.OBJECTIVE To investigate multiple en face image averaging on OCTA images of the choriocapillaris.DESIGN, SETTING, AND PARTICIPANTS Observational, cross-sectional case series at a referral institutional practice in Los Angeles, California. From the original cohort of 21 healthy individuals, 17 normal eyes of 17 participants were included in the study. The study dates were August to September 2016.EXPOSURES All participants underwent OCTA imaging of the macula covering a 3 × 3-mm area using OCTA software (Cirrus 5000 with AngioPlex; Carl Zeiss Meditec). One eye per participant was repeatedly imaged to obtain 9 OCTA cube scan sets. Registration was first performed using superficial capillary plexus images, and this transformation was then applied to the choriocapillaris images. The 9 registered choriocapillaris images were then averaged. Quantitative parameters were measured on binarized OCTA images and compared with the unaveraged OCTA images. MAIN OUTCOME AND MEASURE Vessel caliber measurement.RESULTS Seventeen eyes of 17 participants (mean [SD] age, 35.1 [6.0] years; 9 [53%] female; and 9 [53%] of white race/ethnicity) with sufficient image quality were included in this analysis. The single unaveraged images demonstrated a granular appearance, and the vascular pattern was difficult to discern. After averaging, en face choriocapillaris images showed a meshwork appearance. The mean (SD) diameter of the vessels was 22.8 (5.8) μm (range, 9.6-40.2 μm). Compared with the single unaveraged images, the averaged images showed more flow voids (1423( flow voids [95% CI, 967-1909 vs 1254 flow voids [95% CI, 825-1683], P < .001), smaller average size of the flow voids (911 [95% CI, 301-1521] μm 2 vs 1364 [95% CI, 645-2083] μm 2 , P < .001), and greater vessel density (70.7% [95% CI, 61.9%-79.5%] vs 61.9% [95% CI, 56.0%-67.8%], P < .001). The distribution of the number vs sizes of the flow voids was skewed in both unaveraged and averaged images. A linear log-log plot of the distribution showed a more homogeneous distribution in the averaged images compared with the unaveraged images.CONCLUSIONS AND RELEVANCE Multiple en face averaging can improve visualization of the choriocapillaris on OCTA images, transforming the images from a granular appearance to a level where the intervascular spaces can be resolved in healthy volunteers.

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Impact of Multiple En Face Image Averaging on Quantitative Assessment from Optical Coherence Tomography Angiography Images

Cited by 155 publications

References 20 publications

Conjunctival and Intrascleral Vasculatures Assessed Using Anterior Segment Optical Coherence Tomography Angiography in Normal Eyes

Conjunctival and Intrascleral Vasculatures Assessed Using Anterior Segment Optical Coherence Tomography Angiography in Normal Eyes

Impact of image averaging on wide‐field choroidal thickness measurements using enhanced‐depth imaging optical coherence tomography

Choriocapillaris Imaging Using Multiple En Face Optical Coherence Tomography Angiography Image Averaging

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