Diabetic retinopathy grading by digital curvelet transform.
One of the major complications of diabetes is diabetic retinopathy. As manual analysis and diagnosis of large amount of images are time consuming, automatic detection and grading of diabetic retinopathy are desired. In this paper, we use fundus fluorescein angiography and color fundus images simultaneously, extract 6 features employing curvelet transform, and feed them to support vector machine in order to determine diabetic retinopathy severity stages. These features are area of blood vessels, area, regularity of foveal avascular zone, and the number of micro-aneurisms therein, total number of micro-aneurisms, and area of exudates. In order to extract exudates and vessels, we respectively modify curvelet coefficients of color fundus images and angiograms. The end points of extracted vessels in predefined region of interest based on optic disk are connected together to segment foveal avascular zone region. To extract micro-aneurisms from angiogram, first extracted vessels are subtracted from original image, and after removing detected background by morphological operators and enhancing bright small pixels, micro-aneurisms are detected. 70 patients were involved in this study to classify diabetic retinopathy into 3 groups, that is, (1) no diabetic retinopathy, (2) mild/moderate nonproliferative diabetic retinopathy, (3) severe nonproliferative/proliferative diabetic retinopathy, and our simulations show that the proposed system has sensitivity and specificity of 100% for grading.
Biomedical Engineering Department, Medical Image & Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan 81745319, Iran.
Shirin
S
Hajeb Mohammad Alipour
Hossein
H
Rabbani
Mohammad Reza
MR
Akhlaghi
D000465:Algorithms; D000792:Angiography / Q000379:methods; D001703:Biophysics / Q000379:methods; D049109:Cell Proliferation; D003116:Color; D003198:Computer Simulation; D003287:Contrast Media / Q000494:pharmacology; D003930:Diabetic Retinopathy / Q000145:classification / Q000175:diagnosis* / Q000473:pathology; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D019793:Fluorescein / Q000737:chemistry; D005654:Fundus Oculi; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted; D016011:Normal Distribution; D010781:Photography; D012984:Software
D003287:Contrast Media; D019793:Fluorescein