In many medical image applications, high-resolution images are needed to facilitate early diagnosis. However, due to technical limitations, it may not be easy to obtain an image with ideal resolution especially for the diffusion weighted imaging (DWI). Super-resolution (SR) technology is developed to solve this problem by generating high-resolution (HR) images from low-resolution (LR) images. The purpose of this study is to obtain the SR-DWI from the original LR image through deep super-resolution network. The effectiveness of the SR image is assessed by radiomic analysis in predicting the histological grade of breast cancer. To this end, a dataset of 144 breast cancer cases were collected, including 83 cases who diagnosed as high-grade malignant (Grade 3) breast cancer, and 61 who were median-grade malignant (Grade 2). For each case, the dynamic enhanced magnetic resonance imaging (DCE-MRI), and the apparent diffusion coefficients (ADC) map derived from DWI were obtained. Lesion segmentation was performed on each of the original ADC and the SR-ADC, in which 30 texture and 10 statistical features were extracted. Deep SR model was established by an end-to-end training from the LR DCE-MRI and the HR counterparts and was applied to the ADC images to obtain SR-ADCs. Univariate and multivariate logistic regression classifier was implemented to evaluate the performance of the individual feature and collective features, respectively. The model performance was evaluated by the area under the curve (AUC) under leave one-out cross-validation (LOOCV). For the individual feature analysis, the performance in terms of AUC was significantly better based on the SR-ADC image than that based on the original ADC image. For multivariate analysis, the classifier performance in terms of AUCs were 0.848±0.061 and 0.878±0.051 for the original ADC and the SR ADC, respectively. The results suggested that the enhanced resolution of ADC image had the potential to more accurately predict histological grade in breast cancer.
Breast cancer is one of the most common malignant tumors in women. The purpose of this study was to predict the histological grade of breast cancer using features extracted from dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) and diffusion weighted imaging (DWI). In this study, we collected 144 cases of breast invasive ductal carcinoma, which consists of 76 who were high-grade malignant (Grade 3) and 68 mediate-grade malignant (Grade 2) breast cancers. Preoperative breast DW and DCE-MR examination were performed using a 3T MR scanner. Breast tumor segmentation was performed on all of the image series. After that, image features of texture, statistic, and morphological features of breast tumor were extracted on both the DW and DCE-MR images. The classification model was established on these images respectively, and the classifiers of single-parametric image were fused for prediction. In order to evaluate the classifier performance, the area under the receiver operating characteristic curve (AUC) was calculated in a leave-oneout cross-validation (LOOCV) analysis. The predictive model based on DCE-MRI generated an AUC of 0.829 with the sensitivity and specificity of 0.868 and 0.676 respectively, while that based on DWI generated an AUC of 0.783 with the sensitivity and specificity of 0.842 and 0.676 respectively. After multi-classifier fusion using features both from the DWI and DCE-MRI, the classification performance was increased to AUC of 0.844±0.067 with the sensitivity and specificity of 0.908 and 0.735 respectively. Our results showed that, compared with each single parametric image alone, the performance of the classifier could be improved by combining features of DCE-MRI and DWI.
Breast cancer histological grade and lymph node status are important in evaluating the prognosis of patients. This study aim to predict these factors by analyzing the heterogeneity of tumor and its adjacent stroma based on dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI). A dataset of 172 patients with surgically verified lymph node status (positive lymph nodes, n=62; negative lymph nodes, n=110) who underwent preoperative DCE-MRI and DWI examination was collected. Among them, 144 cases had available histological grade information, including 56 cases of low-grade (grade 1 and 2), and 88 samples of high-grade (grade 3). To this end, we identified six tumor subregions on DCE-MRI as well as the corresponding subregions on ADC according to their distances to the tumor boundary. The statistical and Haralick texture features were extracted in each subregion, based on which predictive models were built to predict histological grade and lymph node status in breast cancer. An area under a receiver operating characteristic curve (AUC) was computed with a leave-one-out cross-validation (LOOCV) method to assess each classifier’s performance. For histological grade prediction, the classifier using DCE-MRI features in the inner tumor achieved best performance among all the subregions with AUC of 0.859. For lymph node status, classifier based on DCE-MRI features from tumor subregion of proximal peritumoral stromal shell obtained highest AUC of 0.882 among all the regions. Furthermore, the predictions from DCE-MRI and DWI were fused, and the AUC value was increased to 0.895 for discriminating histological grade. Our results demonstrate that DCE-MRI and ADC imaging features are complementary in predicting histological grade in breast cancer.
Human epidermal growth factor receptor-2 (HER2) plays an important role in treatment strategy and prognosis determination in breast cancers. However, breast cancers are characterized by considerable heterogeneity both between and within tumors, which is a key impediment to accurately determine HER2 status for radiomic analysis. To this end, tumor heterogeneity was evaluated by unsupervised decomposition method on breast magnetic resonance imaging (MRI), in which three tumor subregions were generated terms as Input, Fast and Slow. This tumor decomposition was performed by a convex analysis of mixtures (CAM) method, which was designed according to analysis of contrast-enhancement patterns. The study retrospectively investigated 181 patients who underwent dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) examination. Among them, 124 were HER2-negative and 57 were HER2-positive status. Imaging features of texture and histogram were computed in each subregion. Multivariate logistic regression classifiers were trained and validated with leave-one-out cross-validation (LOOCV) method. An area under a receiver operating characteristic curve (AUC) was calculated to assess performance of the classifier. The classifier based on features from Fast subregion obtained an AUC of 0.802 ± 0.067 and was significantly (P = 0.0113) outperformed the classifier based on features from the whole tumors. When the predicted values from the respective classifiers were fused by weighted average, the AUC significantly increased to 0.820 ± 0.063 (P = 0.0011). The results indicate that analysis of intratumor heterogeneity through decomposing method of DCE-MRI has the potential to serve as a marker for predicting HER2 status.
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