Endoscopic Mayo score and Ulcerative Colitis Endoscopic Index of Severity are commonly used scoring systems for the assessment of endoscopic severity of ulcerative colitis. They are based on assigning a score in relation to the disease activity, which creates a rank among the levels, making it an ordinal regression problem. On the other hand, most studies use categorical cross-entropy loss function, which is not optimal for the ordinal regression problem, to train the deep learning models. In this study, we propose a novel loss function called class distance weighted cross-entropy (CDW-CE) that respects the order of the classes and takes the distance of the classes into account in calculation of cost. Experimental evaluations show that CDW-CE outperforms the conventional categorical cross-entropy and CORN framework, which is designed for the ordinal regression problems. In addition, CDW-CE does not require any modifications at the output layer and is compatible with the class activation map visualization techniques.

研究使用新的损失函数: 类距加权交叉熵(CDW-CE)，从而更好地训练用于测量溃疡性结肠炎内窥镜活动的评分系统的深度学习模型，该方法考虑到分类之间的距离和顺序，从而在实验评价和领域专家中优于传统的分类交叉熵损失和其他常用损失函数。

类别距离加权交叉熵损失用于溃疡性结肠炎严重程度评估