Asymmetric Lesion Detection with Geometric Patterns and CNN-SVM Classification

Accepted Manuscript: This is the peer - reviewed version of the article accepted for publication in Computers in Biology and Medicine . This manuscript version is made available under the CC BY - NC - ND license. Abstract In dermoscopic images, which allow visualization of surface skin structures not visible to the naked eye, lesion shape offers vital insights into skin diseases. In clinically practiced methods, asymmetric lesion shape is one of the criteria for diagnosing M elanoma. Initially, we labeled data for a non - annotated dataset with symmetrical information based on clinical assessments . Subsequently, we propose a supporting technique -- a supervised learning image processing algorithm -- to analyze the geometrical pattern of lesion shape, aiding non - experts in understanding the criteria of an asymmetric lesion. We then utilize a pre - trained convolutional neural network (CNN) to extract shape, color, and texture features from dermoscopic images for training a multiclass support vector machine (SVM) classifier, outperforming state - of - the - art methods from the literature. In the geometry - based experiment, we achieved a 99.00% detection rate for dermatological asymmetric lesions. In the CNN - based experiment, the best performance is found 9 4% Kappa Score, 95% Macro F1 - score, and 97 % weighted F1 - score for classifying lesion shapes ( A symmetric, H alf - S ymmetric, and S ymmetric). Introduction Dermatological asymmetry, a cornerstone in skin lesion assessment, refers to disparities observed in the shape, size, or color of moles or lesions [1, 2, 3] . In dermatology, careful examination of the lesion shape is critical, especially when it comes to the possibility that lesions are cancerous, such as Melanoma. The dermatological three - point - checklist for early skin cancer detection has showcased remarkable sensitivity in identifying Melanoma [ 2 ]. The presence of " asymmetry of color and structure in one or two perpendicular axes ", stands as the initial criterion of this checklist [ 2 ]. In this method, asymmetry evaluation entails scrutinizing lesions within a plane bisected by two axes set at 90, assigning a score ranging from 0 to 2 based on the number of axes exhibiting asymmetry in shape, color, or structure.