A collaborative multi-task learning method for BI-RADS category 4 breast lesion segmentation and classification of MRI images

Background and objective: The diagnosis of BI-RADS category 4 breast lesion is difficult because its probability of malignancy ranges from 2% to 95%. For BI-RADS category 4 breast lesions, MRI is one of the prominent noninvasive imaging techniques. In this paper, we research computer algorithms to segment lesions and classify the benign or malignant lesions in MRI images. However, this task is challenging because the BI-RADS category 4 lesions are characterized by irregular shape, imbalanced class, and low contrast. Methods: We fully utilize the intrinsic correlation between segmentation and classification tasks, where accurate segmentation will yield accurate classification results, and classification results will promote better segmentation. Therefore, we propose a collaborative multi-task algorithm (CMTL-SC). Specifically, a preliminary segmentation subnet is designed to identify the boundaries, locations and segmentation masks of lesions; a classification subnet, which combines the information provided by the preliminary segmentation, is designed to achieve benign or malignant classification; a repartition segmentation subnet which aggregates the benign or malignant results, is designed to refine the lesion segment. The three subnets work cooperatively so that the CMTL-SC can identify the lesions better which solves the three challenges. Results and conclusion: We collect MRI data from 248 patients in the Second Hospital of Dalian Medical University. The results show that the lesion boundaries delineated by the CMTL-SC are close to the boundaries delineated by the physicians. Moreover, the CMTL-SC yields better results than the single-task and multi-task state-of-the-art algorithms. Therefore, CMTL-SC can help doctors make precise diagnoses and refine treatments for patients.