Automatic diagnosis of abnormal macula in retinal optical coherence tomography images using wavelet based convolutional neural network features and random forests classifier
Abstract. The present research intends to propose a fully automatic algorithm for the classification of three dimensional (3 D) optical coherence tomography (OCT) scans of patients suffering from abnormal macula from normal candidates. The method proposed does not require any denoising, segmentation, retinal alignment processes to assess the intraretinal layers, as well as abnormalities or lesion structures. To classify abnormal cases from the control group, a two stage scheme was utilized, which consists of automatic subsystems for adaptive feature learning and diagnostic scoring. In the first stage, a wavelet based convolutional neural network (CNN) model was introduced and exploited to generate B scan representative CNN codes in the spatial frequency domain, and the cumulative features of 3 D volumes were extracted. In the second stage, the presence of abnormalities in 3 D OCTs was scored over the extracted features. Two different retinal SD OCT datasets are used for evaluation of the algorithm based on the unbiased fivefold cross validation (CV) approach. The first set constitutes 3 D OCT images of 30 normal subjects and 30 diabetic macular edema (DME) patients captured from the Topcon device. The second publicly available set consists of 45 subjects with a distribution of 15 patients in age related macular degeneration, DME, and normal classes from the Heidelberg device. With the application of the algorithm on overall OCT volumes and 10 repetitions of the fivefold CV, the proposed scheme obtained an average precision of 99.33% on dataset1 as a two class classification problem and 98.67% on dataset2 as a three class classification task.
Journal of biomedical optics