DCE-MRI interpolation using learned transformations for breast lesions classification

Automatic differentiation of benign and malignant breast lesions on multiple DCE-MRI series is a challenging task. The performance of the Convolutional Neural Networks (CNNs) based methods is severely affected when the number of DCE-MRI series is inadequate or inconsistent. This paper is motivated by the need of capturing spatial-temporal features from consistent DCE-MRI series for most CNN-based classification methods, and aims at designing an interpolation network that can enlarge the DCE-MRI series. Therefore, our method achieves the objective of breast lesion classification for inconsistent DCE-MRI series with a two-stage method, i.e., DCE-MRI interpolation and classification. Inspired by the learning-based data augmentation, we propose a variable-length multiple DCE-MRI series interpolation method using learned transformations to enlarge DCE-MRI series. Specifically, the forward and backward contrast transformations are learned to estimate the kinetic and spatial variation between different DCE-MRI series. Then, an adaptive warping method is proposed to generate multiple interpolated DCE-MRI series. Finally, the spatial-temporal features are extracted by a new two-stream network from the interpolated DCE-MRI and they are further used to classify breast lesions. We justify the proposed method through extensive experiments using 1223 DCE-MRI slices. Comparing to other methods, it achieves better results on both single series interpolation and multiple series interpolation. The interpolated DCE-MRI greatly improves the classification accuracy nearly by 5% and the best accuracy is 81.9%.