研究目的
To evaluate the validity of an automatic computer-aided diagnosis (CAD) system for detection of retinal nerve fiber layer (RNFL) defects on fundus photographs in optic neuropathy.
研究成果
The proposed CAD system successfully detected RNFL defects with high sensitivity and specificity, making it useful for assisting ophthalmologists in diagnosing optic neuropathies from fundus photographs.
研究不足
The number of images used was not large; structural changes of the optic disc were not considered; high rate of false positives per image; diffuse RNFL defects in advanced cases cannot be detected.
1:Experimental Design and Method Selection:
The study proposed an automatic detection method for RNFL defects using fundus photographs. The method involved preprocessing steps including noise reduction and illumination correction, blood vessel removal, polar coordinate transformation, and Hough transform for line detection, followed by false positive reduction using knowledge-based rules.
2:Sample Selection and Data Sources:
The dataset included 98 fundus photographs from patients with 140 RNFL defects (89 with glaucoma and 9 with nonglaucomatous optic neuropathy) and 100 fundus photographs from healthy normal subjects. Images were obtained from Seoul National University Bundang Hospital using a fundus camera.
3:List of Experimental Equipment and Materials:
Fundus camera (KOWA VX-10; Kowa Company Ltd., Tokyo, Japan), Stratus OCT (Carl Zeiss Meditec, Germany), Spectralis OCT (Heidelberg Engineering, Germany).
4:Experimental Procedures and Operational Workflow:
Images were resized to 1278 x 848 pixels. Preprocessing included noise reduction with a median filter and illumination correction. Blood vessels were removed using morphological bottom-hat transform and Kirsch method. Images were converted to polar coordinates, and RNFL defects were detected using Hough transform. False positives were reduced based on average pixel value, vertical length, and angular location.
5:Data Analysis Methods:
Sensitivity and false positive rates were calculated. Free-response receiver operating characteristics (FROC) analysis was used to evaluate performance.
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