Reliability and reproducibility of macular segmentation using a custom-built optical coherence tomography retinal image analysis software

Abstract

Abstract. We determine the reliability and reproducibility of retinal thickness measurements with a custom-built OCT retinal image analysis software ͑OCTRIMA͒. Ten eyes of five healthy subjects undergo repeated standard macular thickness map scan sessions by two experienced examiners using a Stratus OCT device. Automatic/semi automatic thickness quantification of the macula and intraretinal layers is performed using OCTRIMA software. Intraobserver, interobserver, and intervisit repeatability and reproducibility coefficients, and intraclass correlation coefficients ͑ICCs͒ per scan are calculated. Intraobserver, interobserver, and intervisit variability combined account for less than 5% of total variability for the total retinal thickness measurements and less than 7% for the intraretinal layers except the outer segment/ retinal pigment epithelium ͑RPE͒ junction. There is no significant difference between scans acquired by different observers or during different visits. The ICCs obtained for the intraobserver and intervisit variability tests are greater than 0.75 for the total retina and all intraretinal layers, except the inner nuclear layer intraobserver and interobserver test and the outer plexiform layer, intraobserver, interobserver, and intervisit test. Our results indicate that thickness measurements for the total retina and all intraretinal layers ͑except the outer segment/RPE junction͒ performed using OCTRIMA are highly repeatable and reproducible.

Improving image segmentation performance and quantitative analysis via a computer-aided grading methodology for optical coherence tomography retinal image analysis

“…The OCT-RIMA's norm is based on data from 74 healthy subjects ͑35Ϯ 13 years͒ as described previously. 22 In addition, OCT- ͑inner nuclear layer͒, OPL ͑outer plexiform layer͒, ONL ͑outer nuclear layer͒, OS ͑outer segment of photoreceptors͒, and retinal pigment epithelial layer ͑RPE͒. We note that the sublayer labeled as ONL is actually enclosing the external limiting membrane ͑ELM͒ and IS, but in the standard 10-m resolution OCT image this thin membrane cannot be visualized clearly, making the segmentation of the IS difficult.…”

“…However, our preprocessing method and quantitative methodology for OCT images could be used to automatically segment the retinal structure in both normal and pathological subjects. 6,19,21,22,33 Although our methodology was initially developed for the quantitative analysis of Stratus OCT images, it is also potentially useful for the analysis of new OCT technologies, such as spectral domain and ultrahigh resolutionbased OCT technology, which provide images with higher resolution along with a dense map of the retina. This particular methodology could help ophthalmologists explore Stratus OCT data by providing visualization and analysis methods, in conjunction with a segmentation method for extracting retinal layers and other structures, such as intraretinal and subretinal fluid-filled regions.…”

“…6,19,21,22,33 Accordingly, a more robust and localized quantification of the retinal structure can be achieved using this methodology. The thickness differences between Stratus OCT and OCTRIMA calculations obtained with the convention adopted by Stratus OCT ͑i.e., inner border of the innermost hyperreflective band as the outer retinal border͒ could be explained by Stratus OCT algorithm errors in the segmentation of the inner and outer borders of the retina, differences in interpolation algorithms, and scan realignment methods.…”

“…13,19,21 In this work we aim to describe the correlation between Stratus OCT and OCTRIMA-derived thickness data, along with the intergrader and intragrader reproducibility of OCT-RIMA segmentation using a set of data described previously. 22 In addition, we describe how this tool corrects erroneous automatic segmentation results, and also demonstrate the applicability of OCTRIMA to images obtained by third and fourth generation OCT devices.…”

“…To demonstrate intragrader and intergarder reproducibility of OCTRIMA and the comparability of STRATUS and OCTRIMA-derived thickness results, we used the same set of ten healthy eyes ͑total of 60 OCT B-scans͒ from five normal subjects as reported previously, ranging in age from 25 to 34 years ͑mean age 29 years͒. 22 As in some Fourier-domain OCT ͑FD-OCT͒ systems, OCTRIMA facilitates the total retinal thickness calculations between the inner limiting membrane ͑ILM͒ and the inner boundary of the second hyperreflective band, which has been attributed to the outer segment/retinal pigment epithelium ͑OS/RPE͒ junction in agreement with histological studies. 14,23,24 ͑see Fig.…”