Comparison of Choroidal Vascularity Markers on Optical Coherence Tomography Using Two-Image Binarization Techniques

Area of Science:

• Ophthalmology
• Medical Imaging
• Biomedical Engineering

Background:

• Choroidal vascularity assessment is crucial for diagnosing and monitoring various eye diseases.
• Optical coherence tomography (OCT) provides high-resolution cross-sectional images of the choroid.
• Image binarization techniques are used to quantify choroidal vascularity from OCT images.

Purpose of the Study:

• To compare the agreement between two established image binarization techniques for measuring choroidal vascularity using OCT.
• To evaluate the reliability of choroidal vascularity markers derived from different algorithms.

Main Methods:

• Spectral-domain OCT with enhanced-depth imaging was used in 100 eyes of 52 normal subjects.
• Choroidal images were processed using two distinct binarization algorithms to calculate luminal and stromal areas.
• Choroidal vascularity markers, specifically the luminal/choroidal area ratio (L/C ratio) and choroidal vascularity index (CVI), were computed.
• Intraclass correlation coefficient (ICC) and Bland-Altman analysis were employed to assess agreement.

Main Results:

• Mean choroidal vascularity values were 70.12% for CVI and 67.44% for L/C ratio.
• A low level of absolute agreement was observed between the two techniques, with an adjusted ICC of 0.353.
• Significant discrepancies exist in choroidal vascularity measurements based on the chosen binarization algorithm.

Conclusions:

• There is a notable discrepancy in choroidal vascularity measurements obtained using two common OCT image binarization techniques.
• The accuracy of current binarization algorithms for determining true choroidal vascularity remains uncertain.
• Further research with improved image quality and advanced algorithms is necessary to establish reliable ground truth for choroidal vascularity assessment.