Calculation of the Choroidal Vascularity Index and Tissue Distribution Indexes in Different Retinal and Choroidal Regions by Employing Digital Image Processing Techniques in Optical Coherence Tomography Images

Year 2023, Volume: 33 Issue: 6, 785 - 795, 31.12.2023

Onur İnam , Deniz Somer , Güner Üney , Abdullah Soylu

https://doi.org/10.54005/geneltip.1349861

Abstract

Objective: In this study, it is aimed to investigate the optical coherence tomography images of healthy subjects for various parameters and tissue distribution indexes.
Materials and Methods: 100 eyes of 50 healthy case’s optical coherence tomography (OCT) images have been employed for analysis. Total retinal area (TRA), dark retinal area (DRA), light retinal area (LRA), dark area percent (DAP) and light area percent (LAP) as retinal measurements; total choroidal area (TCA), luminal choroidal area (LCA), stromal choroidal area (SCA), luminal area percent or choroidal vascularity index (CVI) and stromal area percent (SAP) as choroidal measurements have been investigated for vertical and horizontal OCT scans. 6500 µm of the total retinal and choroidal area have been binarized and analyzed in 100 µm intervals and further divided into three main parts: inner, middle, and outer.
Results: CVI value for the entire vertical scan is 69.2±2.6, whereas the entire horizontal scan is 70.1±2.7 (p=0.019). Entire inner part CVI of the vertical scans are calculated as 74.5±4.6 and in horizontal scans as 74.8±5.0 (p=0.678). Vertical CVI of the entire middle part has higher values as 67.2 ± 3.9 than the horizontal scans as 66.0±4.1 (p=0.025). This was conversely recorded at the entire outer part, which the vertical CVI value is 66.6±4.3 and horizontal CVI value is 70.3±4.7 (p<0.001). Although there was no statistically significant difference for any of the TRA comparisons for entire region of interest, entire inner, entire middle and entire outer parts between vertical and horizontal scans (p=0.386, p=0.422, p=0.309 and p=0.352 respectively), vertical TCA measurements were significantly higher than the horizontal scans (p=0.010, p=0.013, p=0.012 and p=0.008, respectively).
Conclusion: CVI and other parameters and tissue distribution indexes could be a valuable tool for differentiating and evaluating the retinal and choroidal conditions in different scan regions.

Keywords

Biophysics, Image Processing, Optical Coherence Tomography, Retina, Choroid

Optik Koherens Tomografi Görüntülerinde Dijital Görüntü İşleme Teknikleri Kullanılarak Farklı Retina ve Koroid Bölgelerindeki Koroid Vaskülarite İndeksi ve Doku Dağılım İndekslerinin Hesaplanması

Abstract

Amaç: Bu çalışmada, sağlıklı bireylerin optik koherens tomografi görüntülerinin çeşitli parametreler ve doku dağılım indeksleri açısından incelenmesi amaçlanmaktadır.
Gereç ve Yöntemler: 50 sağlıklı bireyin 100 gözünün optik koherens tomografi (OKT) görüntüleri analiz için kullanılmıştır. Toplam retina alanı (TRA), karanlık retina alanı (DRA), aydınlık retina alanı (LRA), karanlık alan yüzdesi (DAP) ve aydınlık alan yüzdesi (LAP) gibi retina ölçümleri; toplam koroid alanı (TCA), lüminal koroidal alan (LCA), stromal koroidal alan (SCA), lüminal alan yüzdesi veya koroidal vaskülerite indeksi (CVI) ve stromal alan yüzdesi (SAP) gibi koroidal ölçümler, dikey ve yatay OKT taramaları için incelendi. Toplam retinal ve koroidal alanın 6500 µm'si 100 µm aralıklarla binarize hale getirilip analiz edildi ve daha sonra iç, orta ve dış olmak üzere üç ana bölüme ayrıldı.
Bulgular: Tüm dikey tarama CVI değeri 69.2±2.6 iken, tüm yatay tarama için bu değer 70.1±2.7 olarak hesaplandı (p=0.019). Dikey taramalar için tüm iç bölüm CVI değeri 74.5±4.6 ve yatay taramalar için 74.8±5.0 olarak hesaplandı (p=0.678). Tüm orta bölüm dikey CVI değeri 67.2 ± 3.9 iken yatay taramalarda 66.0±4.1 olarak bulundu (p=0.025). Bu durum tüm dış bölüm için tersiydi; dikey CVI değeri 66.6±4.3 iken yatay CVI değeri 70.3±4.7 olarak bulundu (p<0.001). TRA karşılaştırmalarının hiçbirinde, tüm bölüm, iç bölüm, orta bölüm ve dış bölüm için dikey ve yatay taramalar arasında istatistiksel olarak anlamlı fark bulunmadı (sırasıyla p=0.386, p=0.422, p=0.309 ve p=0.352). Ancak dikey TCA ölçümleri, yatay taramalara göre istatistiksel olarak anlamlı şekilde yüksek bulundu (sırasıyla p=0.010, p=0.013, p=0.012 ve p=0.008).
Sonuç: CVI, diğer parametreler ve doku dağılım indeksleri, farklı tarama bölgelerinde retinal ve koroidal durumları ayırt etmek ve değerlendirmek için değerli bir araç olabilir.

Keywords

Biyofizik, Görüntü İşleme, optik koherens tomografi, Retina, Koroid

References

• Gupta MP, Herzlich AA, Sauer T, Chan CC. Retinal Anatomy and Pathology. Developments in ophthalmology. 2016;55:7-17.
• Masland Richard H. The Neuronal Organization of the Retina. Neuron. 2012;76(2):266-80.
• Hildebrand GD, Fielder AR. Anatomy and Physiology of the Retina. In: Reynolds J, Olitsky S, editors. Pediatric Retina. Berlin, Heidelberg: Springer Berlin Heidelberg; 2011. p. 39-65.
• Nickla DL, Wallman J. The multifunctional choroid. Progress in retinal and eye research. 2010;29(2):144-68.
• Ferrara D, Waheed NK, Duker JS. Investigating the choriocapillaris and choroidal vasculature with new optical coherence tomography technologies. Progress in retinal and eye research. 2016;52:130-55.
• Alm A, Nilsson SF. Uveoscleral outflow--a review. Experimental eye research. 2009;88(4):760-8.
• De Stefano ME, Mugnaini E. Fine structure of the choroidal coat of the avian eye. Lymphatic vessels. Invest Ophthalmol Vis Sci. 1997;38(6):1241-60.
• Bajwa A, Aman R, Reddy AK. A comprehensive review of diagnostic imaging technologies to evaluate the retina and the optic disk. International ophthalmology. 2015;35(5):733-55.
• Murthy RK, Haji S, Sambhav K, Grover S, Chalam KV. Clinical applications of spectral domain optical coherence tomography in retinal diseases. Biomedical journal. 2016;39(2):107-20.
• Boccara C, Dubois A. Optical Coherence Tomography. In: Goure J, editor. Optics in Instruments: Applications in Biology and Medicine. Wiley Online Books: John Wiley & Sons, Inc.; 2013.
• Huang D, Swanson EA, Lin CP, Schuman JS, Stinson WG, Chang W, et al. Optical coherence tomography. Science (New York, NY). 1991;254(5035):1178-81.
• Hee MR, Puliafito CA, Wong C, Reichel E, Duker JS, Schuman JS, et al. Optical coherence tomography of central serous chorioretinopathy. Am J Ophthalmol. 1995;120(1):65-74.
• Schuman JS, Hee MR, Arya AV, Pedut-Kloizman T, Puliafito CA, Fujimoto JG, et al. Optical coherence tomography: a new tool for glaucoma diagnosis. Current opinion in ophthalmology. 1995;6(2):89-95.
• Hee MR, Baumal CR, Puliafito CA, Duker JS, Reichel E, Wilkins JR, et al. Optical coherence tomography of age-related macular degeneration and choroidal neovascularization. Ophthalmology. 1996;103(8):1260-70.
• Hee MR, Puliafito CA, Wong C, Duker JS, Reichel E, Rutledge B, et al. Quantitative assessment of macular edema with optical coherence tomography. Archives of ophthalmology (Chicago, Ill : 1960). 1995;113(8):1019-29.
• Hee MR, Puliafito CA, Wong C, Duker JS, Reichel E, Schuman JS, et al. Optical coherence tomography of macular holes. Ophthalmology. 1995;102(5):748-56.
• Nassif NA, Cense B, Park BH, Pierce MC, Yun SH, Bouma BE, et al. In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve. Opt Express. 2004;12(3):367-76.
• Sull AC, Vuong LN, Price LL, Srinivasan VJ, Gorczynska I, Fujimoto JG, et al. Comparison of spectral/Fourier domain optical coherence tomography instruments for assessment of normal macular thickness. Retina. 2010;30(2):235-45.
• Klein T, Wieser W, Reznicek L, Neubauer A, Kampik A, Huber R. Multi-MHz retinal OCT. Biomed Opt Express. 2013;4(10):1890-908.
• Margolis R, Spaide RF. A pilot study of enhanced depth imaging optical coherence tomography of the choroid in normal eyes. Am J Ophthalmol. 2009;147(5):811-5.
• Agrawal R, Gupta P, Tan KA, Cheung CM, Wong TY, Cheng CY. Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study. Scientific reports. 2016;6:21090.
• Agrawal R, Chhablani J, Tan KA, Shah S, Sarvaiya C, Banker A. CHOROIDAL VASCULARITY INDEX IN CENTRAL SEROUS CHORIORETINOPATHY. Retina. 2016;36(9):1646-51.
• Agrawal R, Li LK, Nakhate V, Khandelwal N, Mahendradas P. Choroidal Vascularity Index in Vogt-Koyanagi-Harada Disease: An EDI-OCT Derived Tool for Monitoring Disease Progression. Translational vision science & technology. 2016;5(4):7.
• Agrawal R, Salman M, Tan KA, Karampelas M, Sim DA, Keane PA, et al. Choroidal Vascularity Index (CVI)--A Novel Optical Coherence Tomography Parameter for Monitoring Patients with Panuveitis? PLoS One. 2016;11(1):e0146344.
• Tan KA, Laude A, Yip V, Loo E, Wong EP, Agrawal R. Choroidal vascularity index - a novel optical coherence tomography parameter for disease monitoring in diabetes mellitus? Acta ophthalmologica. 2016;94(7):e612-e6.
• Wei X, Ting DSW, Ng WY, Khandelwal N, Agrawal R, Cheung CMG. CHOROIDAL VASCULARITY INDEX: A Novel Optical Coherence Tomography Based Parameter in Patients With Exudative Age-Related Macular Degeneration. Retina. 2017;37(6):1120-5.
• Schindelin J, Arganda-Carreras I, Frise E, Kaynig V, Longair M, Pietzsch T, et al. Fiji: an open-source platform for biological-image analysis. Nature methods. 2012;9(7):676-82.
• Schneider CA, Rasband WS, Eliceiri KW. NIH Image to ImageJ: 25 years of image analysis. Nature methods. 2012;9:671.
• İnam O. Calculation of choroidal vascularity index and tissue distribution indexes by digital processing of retinal and choroidal images obtained via optical coherence tomography [Doctorate Thesis]. Ankara: Hacettepe University Graduate School of Health Sciences; 2018.
• Hoon M, Okawa H, Della Santina L, Wong RO. Functional architecture of the retina: development and disease. Progress in retinal and eye research. 2014;42:44-84.
• Gonzalez Caldito N, Antony B, He Y, Lang A, Nguyen J, Rothman A, et al. Analysis of Agreement of Retinal-Layer Thickness Measures Derived from the Segmentation of Horizontal and Vertical Spectralis OCT Macular Scans. Current Eye Research. 2018;43(3):415-23.
• Agarwal A, Agrawal R, Khandelwal N, Invernizzi A, Aggarwal K, Sharma A, et al. Choroidal Structural Changes in Tubercular Multifocal Serpiginoid Choroiditis. Ocul Immunol Inflamm. 2017:1-7.
• Shin JW, Shin YU, Cho HY, Lee BR. Measurement of choroidal thickness in normal eyes using 3D OCT-1000 spectral domain optical coherence tomography. Korean journal of ophthalmology : KJO. 2012;26(4):255-9.
• Ng WY, Ting DS, Agrawal R, Khandelwal N, Htoon HM, Lee SY, et al. Choroidal Structural Changes in Myopic Choroidal Neovascularization After Treatment With Antivascular Endothelial Growth Factor Over 1 Year. Invest Ophthalmol Vis Sci. 2016;57(11):4933-9.
• Koh LHL, Agrawal R, Khandelwal N, Sai Charan L, Chhablani J. Choroidal vascular changes in age-related macular degeneration. Acta ophthalmologica. 2017;95(7):e597-e601.