Curriculum Learning Based Approach to Captioning Ultrasound Images.

We present a novel curriculum learning approach to train a natural language processing (NLP) based fetal ultrasound image captioning model. Datasets containing medical images and corresponding textual descriptions are relatively rare and hence, smaller-sized when compared to the datasets of natural images and their captions. This fact inspired us to develop an approach to train a captioning model suitable for small-sized medical data. Our datasets are prepared using real-world ultrasound video along with synchronised and transcribed sonographer speech recordings. We propose a "dual-curriculum" method for the ultrasound image captioning problem. The method relies on building and learning from curricula of image and text information for the ultrasound image captioning problem. We compare several distance measures for creating the dual curriculum and observe the best performance using the Wasserstein distance for image information and tf-idf metric for text information. The evaluation results show an improvement in all performance metrics when using curriculum learning over stochastic mini-batch training for the individual task of image classification as well as using a dual curriculum for image captioning.