Elsevier

Pattern Recognition

Volume 131, November 2022, 108858
Pattern Recognition

Multi-feature deep information bottleneck network for breast cancer classification in contrast enhanced spectral mammography

https://doi.org/10.1016/j.patcog.2022.108858Get rights and content

Highlights

  • First information bottleneck based-deep learning study for classifying breast cancer.

  • Multi-feature deep information bottleneck is introduced.

  • The features between contrast enhanced spectral mammography are fully explored.

  • Multiple image features are considered simultaneously in relation to the labels.

Abstract

There is considerable variation in the size, shape and location of tumours, which makes it challenging for radiologists to diagnose breast cancer. Automated diagnosis of breast cancer from Contrast Enhanced Spectral Mammography (CESM) can support clinical decision making. However, existing methods fail to obtain an effective representation of the CESM and ignore the relationships between images. In this paper, we investigated for the first time a novel and flexible multimodal representation learning method, multi-feature deep information bottleneck (MDIB), for breast cancer classification in CESM. Specifically, the method incorporated an information bottleneck (IB)-based module to learn the prominent representation that provide concise input while informative for the classification. In addition, we creatively extended IB theory to multi-feature IB, which facilitates the learning of relevant features for classification between CESM images. To validate our method, experiments were conducted on our private and public datasets. The classification results of our method were also compared with those of state-of-the-art methods. The experiment results proved the effectiveness and the efficiency of the proposed method. We release our code at https://github.com/sjq5263/MDIB-for-CESM-classification.

Introduction

Breast cancer is the second leading cause of cancer death among women worldwide [1]. Early detection is a primary means of reducing breast cancer-related mortality [2]. Several medical imaging modalities are available for the diagnosis of breast cancer, including mammography, ultrasound, MRI and contrast enhanced spectral mammography (CESM). Compared to other imaging modalities, CESM provides low-energy (LE), dual-energy subtracted (DES) modalities images with craniocaudal (CC) and mediolateral oblique (MLO) view of the breast. A set of typical CESM images are presented in Fig. 1. Mammographic findings such as calcifications and masses can be seen from LE image. The DES provides images of enhanced areas due to increased perfusion of breast tissue at the site of the malignancy [3]. In addition, radiologists can view the breast area from multiple perspectives (CC and MLO views). The multi-view multi-modal images in CESM provide more information about the lesion area for the patient’s cancerous condition. Many preliminary studies also confirmed that the sensitivity and specificity of CESM are superior to mammography. Despite improved consistency, variations in the subjective description of imaging findings and limitations in expert experience and effort [4] remain a significant impediment to the accurate diagnosis of CESM.

An automated diagnosis system can be used to tackle the aforementioned problems, which has shown significant results in breast cancer classification. The method based on traditional machine learning (ML) algorithms can focus on radiomics features explicitly selected by domain experts, which relies on certain hand-crafted features. Recently, deep learning (DL) has been used for image classification for its superior performance with end-to-end pipeline automation, which can learn appropriate predictive features in images. After the success of convolutional neural networks (CNN), DL outperforms traditional ML algorithms in computer vision. As artificial intelligence (AI) evolves, DL methods have rivaled the performance of medical experts through learning from a large number of images.

Recently, many researchers utilized DL approaches for the classification of breast cancer in CESM images. Gao et al. [5] proposed a modified DL architecture to improve the classification performance of breast cancer using CESM images. Perek et al. [6] incorporated breast imaging reporting and data systems textual features into AI framework for improving classification accuracy. However, the classification performance of these studies did not achieve optimal results for the following reasons. Firstly, the designed methods only adopted general techniques which cannot accurately learn the representation of breast images, resulting in poor model performance. Secondly, most of these methods used unimodal or single-view breast images and did not utilize multi-featured CESM images by using explicit images as an input to the classification model. Finally, it is well known that the different modalities of breast images (LE and DES) are theoretically able to provide similar information for the lesion area of disease, improving the accuracy of malignant tumors. However, previous studies did not explore the relationship between the different modalities of CESM.

To break through the limitations of previous methods, we creatively conducted a multi-feature deep information bottleneck (MDIB) network for classification of breast cancer, which effectively represents CESM images. Our proposed model makes full use of the multimodal (LE and DES) and multiview (CC and MLO) feature characteristics of CESM images to achieve more accurate classification results. The proposed algorithm has outperformed general DL methods in many aspects. The contributions of this study are threefold. (1) We introduce a DL model, MDIB, which combines IB to learn the more accurate representation of CESM images for classification. To the best of our knowledge, this is the first study to classify CESM images using IB theory. (2) We theoretically extend the IB theory to multiple features. The proposed strategy can extract concise representations between inputs and labels as well as common features between modalities to achieve accurate classification. (3) We conduct an extensive evaluation on our private and a public CESM dataset, and the experimental results validate the effectiveness of the proposed multi-feature IB network for CESM image classification. Promising generalization capabilities are shown empirically compared to state-of-the-art methods.

Section snippets

Multimodal medical image classification

With the extension of clinical applications of various medical imaging systems, multimodal imaging starts playing an increasingly important role [7]. The multimodal medical image (CT, MRI, PET, etc.) typically involves different information with a partial aspect of patient’s condition, which can provide complementary information to another modality [8]. Methods for multimodal medical image classification can be broadly classified into ML-based [9], [10] and DL-based methods [11]. In [12],

Method

We start this section by motivating and giving intuition behind our approach. Then, we introduce the architecture of the proposed method. After that we explain the loss function that is based on IB theory.

Data

We report the performance of the proposed model on private and public datasets. We retrospectively collected CESM from 95 patients aged 21 to 74 years between July 2018 to April 2020 to form our private dataset. The dataset consists of 760 images. Before using the dataset, we preprocessed the data to remove the sensitive information about the patients. Eight images (4 images per unilateral breast) were collected per patient. One patient was considered as two cases because of the different

Discussion

In this study, we applied multi-feature deep information bottleneck theory to network for CESM image classification. The proposed method outperforms the previously available methods in several aspects. First, from Fig. 3, the proposed method with the information bottleneck strategy achieves better results than base models. In addition, the model with two losses of IB works significantly better. The IB strategy allows the model to learn the exact representation between CESM images and labels. We

Conclusion

Based on the analysis characteristics of CESM images, a novel multi-feature deep information bottleneck network is first proposed for CESM classification. The proposed method outperforms state-of-the-art methods for breast cancer classification using CESM images on both private and public datasets. The reason lies in the fact that it makes use of the information bottleneck theory to produce a concise and informative representation of the classification. In addition, the proposed multi-feature

Funding

This work was supported by the National Natural Science Foundation of China [grant numbers 81871508 and 61773246]; the Major Program of Shandong Province Natural Science Foundation [grant number ZR2018ZB0419]; the Major Basic Research Program of Natural Science Foundation of Shandong Province [grant number ZR2019ZD04]; Shandong Provincial Natural Science Foundation Joint Fund [grant number ZR2021LZL011]; and the Taishan Scholar Foundation of Shandong Province [grant number TSHW201502038].

Ethical approval and informed consent

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

Availability of data and materials

The dataset during the current study is available from the corresponding author on reasonable request.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Jingqi Song is currently a PhD candidate at the school of information science and engineering of Shandong Normal University. His current research interests include medical image processing, image classification, and deep learning.

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      Most breast tumor diagnosis methods using multi-modality images mainly focus on the classification step, and the diagnosis results can be obtained by combining the classification information of multiple modalities. However, problems arise for existing breast tumor classification methods with multimodality images, and the useful correlation information between mammography and ultrasound is ignored [11–14]. Generally, there exist inherent correlations between these two modalities for the same patient because the underlying pathology is the same, that is, the diagnosis results based on mammography and ultrasound for the same patient should be consistent [15].

    Jingqi Song is currently a PhD candidate at the school of information science and engineering of Shandong Normal University. His current research interests include medical image processing, image classification, and deep learning.

    Yuanjie Zheng is a professor in the school of information science and engineering at the Shandong Normal University. He has a PhD degree fromiversity of Pennsylvania, USA.is research interests includemputer vision, medical image processing and pattern recognition areas.

    Jing Wang is currently a PhD candidate at the school of information science and engineering of Shandong Normal University. Her current research interests include image classification and image detection.

    Muhammad Zakir Ullah is currently a MSc candidate at the school of information science and engineering of Shandong Normal University. His current research interests include medical image processing, machine learning and deep learning.

    Xuecheng Li is currently a MSc candidate at the school of information science and engineering of Shandong Normal University. His current research interests include medical image segmentation and detection.

    Zhenxing Zou is a Radiologist at Medical Imaging Department of Yantai Yuhuangding Hospital.

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