DETERMINATION OF FISH GENDER USING FRACTAL ANALYSIS OF ULTRASOUND IMAGES

• Published in: Veterinary Radiology & Ultrasound
• Main Authors: MCEVOY, FINTAN J., TOMKIEWICZ, JONNA, STØTTRUP, JOSIANNE G., OVERTON, JULIE L., MCEVOY, CONNI, SVALASTOGA, EILIV
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2009
• Subjects: Gadus morhua
• Online Access: http://dx.doi.org/10.1111/j.1740-8261.2009.01568.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1740-8261.2009.01568.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1740-8261.2009.01568.x

The gender of cod Gadus morhua can be determined by considering the complexity in their gonadal ultrasonographic appearance. The fractal dimension ( D B ) can be used to describe this feature in images. B‐mode gonadal ultrasound images in 32 cod, where gender was known, were collected. Fractal analysis was performed on these images and D B was determined using the box counting method. A receiver–operating curve (ROC) was drawn for D B as a test for male fish. Using a range of D B values, the maximum accuracy for this test was calculated and compared with the accuracy for identifying male fish by subjective analysis alone. The mean (and standard deviation) of the fractal dimension D B for male fish was 1.554 (0.073) while for female fish it was 1.468 (0.061); the difference was statistically significant ( P =0.001). The area under the ROC curve was 0.84 indicating the value of fractal analysis in gender determination in cod. Maximum accuracy (0.84) for D B as a test for male fish was obtained using the threshold value D B =1.5058 compared with an accuracy of 0.78 for subjective image evaluation. The use of two thresholds, D B <1.4475 (females) and D B >1.5054 (males) gives an 80% certainty in the classification result. Fractal analysis is useful for gender determination in cod. This or a similar form of analysis may have wide application in veterinary imaging as a tool for quantification of complexity in images.