Increasing Melanoma Diagnostic Confidence: Forcing the Convolutional Network to Learn from the Lesion

TL;DR

This paper presents a novel lesion-focused convolutional approach that improves melanoma diagnostic accuracy and confidence by training a model to detect and learn from the lesion itself, reducing reliance on extraneous features.

Contribution

The study introduces a lesion detection and learning technique using an elliptical segmentation model to enhance melanoma recognition and generalization across datasets.

Findings

Improved mean AUC from 0.9 to 0.922 on ISIC 2020 dataset.

Enhanced diagnostic confidence and score separation.

Demonstrated effectiveness of lesion-focused training in melanoma detection.

Abstract

Deep learning implemented with convolutional network architectures can exceed specialists' diagnostic accuracy. However, whole-image deep learning trained on a given dataset may not generalize to other datasets. The problem arises because extra-lesional features - ruler marks, ink marks, and other melanoma correlates - may serve as information leaks. These extra-lesional features, discoverable by heat maps, degrade melanoma diagnostic performance and cause techniques learned on one data set to fail to generalize. We propose a novel technique to improve melanoma recognition by an EfficientNet model. The model trains the network to detect the lesion and learn features from the detected lesion. A generalizable elliptical segmentation model for lesions was developed, with an ellipse enclosing a lesion and the ellipse enclosed by an extended rectangle (bounding box). The minimal bounding box was extended by 20% to allow some background around the lesion. The publicly available International Skin Imaging Collaboration (ISIC) 2020 skin lesion image dataset was used to evaluate the effectiveness of the proposed method. Our test results show that the proposed method improved diagnostic accuracy by increasing the mean area under receiver operating characteristic curve (mean AUC) score from 0.9 to 0.922. Additionally, correctly diagnosed scores are also improved, providing better separation of scores, thereby increasing melanoma diagnostic confidence. The proposed lesion-focused convolutional technique warrants further study.