Abstract

Optical coherence tomography angiography (OCTA) provides several data regarding the status of retinal capillaries. This information can be further enlarged by employing quantitative metrics, such as vessel density (VD). A mandatory preliminary step of OCTA quantification is image binarization, a procedure used to highlight retinal capillaries on empty background. Although several binarization thresholds exist, no consensus is reached about the thresholding technique to be used. In this study, we tested thirteen binarization thresholds on a dataset made by thirty volunteers. The aim was to assess the impact of binarization techniques on: (I) detection of retinal capillaries, assessed by the calculation of overlapping percentages between binarized and original images; (II) quantitative OCTA metrics, including VD, vessel tortuosity (VT) and vessel dispersion (Vdisp); (III) foveal avascular zone (FAZ) detection. Our findings showed Huang, Li, Mean and Percentile as highly reliable binarization thresholds (p < 0.05), whereas the worst binarization thresholds were Intermodes, MaxEntropy, RenylEntropy and Yen (p < 0.05). All the thresholds variably underestimated VD metric and FAZ detection, with respect to the original OCTA images, whereas VT and Vdisp turned out to be more stable. The usage of a Fixed threshold resulted extremely useful to reduce VD and FAZ underestimations, although bound to operators’ experience.

Highlights

  • Optical coherence tomography angiography (OCTA) provides several data regarding the status of retinal capillaries

  • The main aim of the present study is to investigate the impact of the main thresholding techniques on a cohort of healthy eyes analyzed by OCTA and to assess the influence of quantitative OCTA metrics

  • We considered as fixed thresholding values 65 for Superficial capillary plexus (SCP) and deep capillary plexus (DCP), and 85 for CC

Read more

Summary

Introduction

Optical coherence tomography angiography (OCTA) provides several data regarding the status of retinal capillaries This information can be further enlarged by employing quantitative metrics, such as vessel density (VD). The aim was to assess the impact of binarization techniques on: (I) detection of retinal capillaries, assessed by the calculation of overlapping percentages between binarized and original images; (II) quantitative OCTA metrics, including VD, vessel tortuosity (VT) and vessel dispersion (Vdisp); (III) foveal avascular zone (FAZ) detection. Optical coherence tomography angiography (OCTA) is a largely used, non-invasive technique providing extremely detailed information regarding intraretinal vessels and c­ horiocapillaris[1]. The most of these metrics require a preliminary step, represented by image binarization This procedure transforms OCTA greyscale reconstructions into black-white images, highlighting the vessels in the context of the empty background. The main aim of the present study is to investigate the impact of the main thresholding techniques on a cohort of healthy eyes analyzed by OCTA and to assess the influence of quantitative OCTA metrics

Objectives
Methods
Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.