Abstract
Purpose: :
To develop a histogram decomposition model for retinal OCT images and to derive a quantitative parameter, maximum tissue contrast index (mTCI), for assessing OCT signal quality from multiple devices.
Methods: :
An intensity histogram decomposition model was proposed to separate the foreground and background information of OCT images and to calculate the mTCI. 120 multi-frame OCT images from 4 SD OCT devices (Cirrus, Carl Zeiss Meditec, Inc.; RTVue, Optovue, Inc.; Spectralis, Heidelberg Engineering, Inc.; and 3D OCT-1000, Topcon Corporation) were evaluated quantitatively using mTCI. The mTCI results were compared to the manufacturer signal index (MSI) provided by the respective devices, and to a subjective grading scores (SGS) assessed by trained graders using a subjective grading protocol. The paired methods were tested for correlation significance using Pearson Correlation, and followed by Deming regression analysis to establish the correlation parameters.
Results: :
Statistically significant correlations were observed between the paired methods (i.e., SGS and MSI, SGS and mTCI, and mTCI and MSI). One-tail Fisher’s Z transformation showed the Pearson correlation coefficient (ρ ≥ 0.8) for all devices, indicating a linear relationship between the methods. Using the Deming regression, correlation parameters between the paired methods were calculated, which allowed conversion from the proprietary MSI values to SGS and mTCI values that are universally applicable.
Conclusions: :
Signal quality of retinal OCT images can be evaluated and correlated between OCT devices from different manufacturers, both qualitatively through a subjective grading scheme and quantitatively using the mTCI. Together with the proposed histogram decomposition model, mTCI may be used as a standardization metric for OCT signal quality that would impact measurements.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • retina