Weakly Supervised Deep Learning Approach to Breast MRI Assessment

Rationale and Objectives: To evaluate a weakly supervised deep learning approach to breast Magnetic Resonance Imaging (MRI) assessment without pixel level segmentation in order to improve the specificity of breast MRI lesion classification. Materials and Methods: In this IRB approved study, the dataset consisted of 278,685 image slices from 438 patients. The weakly supervised network was based on the Resnet-101 architecture. Training was implemented using the Adam optimizer and a final SoftMax score threshold of 0.5 was used for two class classification (malignant or benign). 278,685 image slices were combined into 92,895 3-channel images. 79,871 (85%) images were used for training and validation while 13,024 (15%) images were separated for testing. Of the testing dataset, 11,498 (88%) were benign and 1531 (12%) were malignant. Model performance was assessed. Results: The weakly supervised network achieved an AUC of 0.92 (SD +/- 0.03) in distinguishing malignant from benign images. The model had an accuracy of 94.2% (SD +/- 3.4) with a sensitivity and specificity of 74.4% (SD +/- 8.5) and 95.3% (SD +/- 3.3) respectively. Conclusion: It is feasible to use a weakly supervised deep learning approach to assess breast MRI images without the need for pixel-by-pixel segmentation yielding a high degree of specificity in lesion classification.