Dynamic Contrast-enhanced Breast MR Images Research Articles

Measuring sparse temporal-variation for accurate registration of dynamic contrast-enhanced breast MR images

Accurate registration of dynamic contrast-enhanced (DCE) MR breast images is challenging due to the temporal variations of image intensity and the non-rigidity of breast motion. The former can cause the well-known tumor shrinking/expanding problem in registration process while the latter complicates the task by requiring an estimation of non-rigid deformation. In this paper, we treat the intensity's temporal variations as “corruptions” which spatially distribute in a sparse pattern and model them with a L1 norm and a Lorentzian norm. We show that these new image similarity measurements can characterize the non-Gaussian property of the difference between the pre-contrast and post-contrast images and help to resolve the shrinking/expanding problem by forgiving significant image variations. Furthermore, we propose an iteratively re-weighted least squares based method and a linear programming based technique for optimizing the objective functions obtained using these two novel norms. We show that these optimization techniques outperform the traditional gradient-descent approach. Experimental results with sequential DCE-MR images from 28 patients show the superior performances of our algorithms.

Evaluation of breast cancer chemotherapy efficacy with multifractal spectrum analysis of magnetic resonance image

Multifractal spectrum analysis of dynamic contrast enhanced (DCE) breast MR images was used to establish a new quantitative analysis method for solid tumor blood perfusion and to explore its applicability in evaluating efficacy of breast cancer chemotherapy. Five randomly selected patients suffering from newly diagnosed malignant breast nodule lesions were enrolled in this study, and four of them were treated with neoadjuvant chemotherapy. Their DCE breast MR images were collected before and after treatment. Chemotherapeutic efficacy was analyzed using international response evaluation criteria for solid tumors (RECIST). Sandbox method for statistical number density was employed to measure and calculate multifractal spectra of DCE breast MR images with spatiotemporal characteristics. Multifractal spectral data of malignant lesions before and after chemotherapy were compared. Multifractal spectra of malignant lesions show an asymmetric bell-shape. Chemotherapy efficacy was assessed to be partial remission (PR) for three patients and their multifractal spectral width significantly increased after chemotherapy while to be stable disease (SD) for other patient and of her changed slightly. Multifractal spectral width correlates with blood-supply condition of tumor lesion before and after chemotherapy, providing a potential suitable characteristic parameter for evaluating chemotherapeutic efficacy quantitatively.

Background parenchymal enhancement on breast MRI: Influence of menstrual cycle and breast composition

To evaluate the menstrual cycle and breast composition influence on background parenchymal enhancement of breast magnetic resonance imaging (MRI) and to investigate the optimal time for breast MR examinations. We evaluated the dynamic contrast-enhanced breast MR images of 238 women who had completed a questionnaire survey about menstrual status. On MRI, the degree of enhancement (DE) of normal parenchyma was measured in the images 2 minutes and 6 minutes after contrast injection. A comparison between premenopausal and postmenopausal women and a separate comparison between dense breasts and fatty breasts were analyzed according to the premenopausal women's menstrual cycle. Premenopausal women showed significantly higher DE than the postmenopausal women (P<0.001). In premenopausal women, overall DE of fatty breasts and dense breasts was not different. However, fatty breasts showed the highest DE in the 4th week and lowest DE in the 2nd week, while dense breasts showed the highest DE in the 3rd week and the lowest DE in the 4th week of menstrual cycle. The influence of menstrual cycle on the enhancement of breast parenchyma is different according to the breast composition. The optimal time for breast MRI could be different for dense and fatty breasts.