Towards localization of malignant sites of asymmetry across bilateral mammograms.

BACKGROUND AND OBJECTIVES: The analysis of patterns of asymmetry between the left and right mammograms of a patient can provide meaningful insights into the presence of an underlying tumor in its early stage. However, the identification of breast cancer by investigating bilateral asymmetry is difficult to perform due to the indistinct and borderline nature of the asymmetric signs as they appear on mammograms. METHODS: In this study, to increase the positive-predictive value of asymmetry in mammographic screening, a novel computerized approach for the automatic localization of malignant sites of asymmetry in mammograms is proposed. The sites of anatomical correspondence between the right and left regions of each radiographic projection were extracted by means of two bilateral masking procedures, inspired by radiologists' criteria in interpreting mammograms and based on the use of detected landmarking structures. Relative variations of spatial patterns of intensity values and of orientations of directional components within each site were quantified by combining multidirectional Gabor filters and indices of structural similarity. The localization of the sites of malignant asymmetry was performed by coupling two quadratic discriminant analysis classifiers, one for each masking procedure, that assigned the likelihood of malignancy to each site of correspondence. RESULTS: The performance of the proposed method was assessed on 94 mammographic images from two publicly available databases and containing at least one asymmetric site. Sensitivity, specificity and balanced accuracy levels of 0.83 (0.09), 0.75 (0.06), and 0.79 (0.04), respectively were obtained in the classification of malignant asymmetric sites vs benign/normal sites using cross-validation. In addition, a further blind test on a dataset of Full Field Digital Mammograms achieved levels of sensitivity, specificity, and balanced accuracy of 0.86, 0.65, and 0.75, respectively. CONCLUSIONS: The achieved performance indicates that the proposed system is effective in localizing sites of malignant asymmetry and it is expected to improve computer-aided diagnosis of breast cancer.

Estimation of the breast skin-line in mammograms using multidirectional Gabor filters.

Segmentation of the breast region is a fundamental step in any system for computerized analysis of mammograms. In this work, we propose a novel procedure for the estimation of the breast skin-line based upon multidirectional Gabor filtering. The method includes an adaptive values-of-interest (VOI) transformation, extraction of the skin-air ribbon by Otsu's thresholding method and the Euclidean distance transform, Gabor filtering with 18 real kernels, and a step for suppression of false edge points using the magnitude and phase responses of the filters. On a test set of 361 images from different acquisition modalities (screen-film and full-field digital mammograms), the average Hausdorff and polyline distances obtained were 2.85 mm and 0.84 mm, respectively, with reference to the ground-truth boundaries provided by an expert radiologist. When compared with the results obtained by other state-of-the-art methods on the same set of images and with respect to the same ground-truth boundaries, our method mostly outperformed the other approaches. The results demonstrate the effectiveness and robustness of the proposed algorithm.

Deep pelvic endometriosis: accuracy of pelvic MRI completed by MR colonography.

PURPOSE: This study assessed the diagnostic accuracy of pelvic magnetic resonance (MR) imaging completed by MR colonography for the preoperative evaluation of deep pelvic endometriosis in patients undergoing laparoscopic surgery. MATERIALS AND METHODS: A total of 143 patients (mean age 34.3 ± 5.1 years) with a clinical suspicion of deep pelvic endometriosis were assessed by pelvic MR and MR colonography. All patients underwent laparoscopic surgery 3-10 weeks after the MR examination. The presence, location, number and extent of endometriotic lesions were evaluated. Data obtained with MR were compared with surgical findings. MR sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and diagnostic accuracy values were calculated for each site by considering the laparoscopic and histological findings as the reference standard. RESULTS: Laparoscopy confirmed the presence of endometriosis in 119/143 patients (83%); in 76/119 (64%) deep pelvic endometriosis was diagnosed, whereas in the remaining 43/119 (36%), superficial peritoneal implants and endometriomas were found. In 32/119 (27%) patients, intestinal lesions were detected. MR had sensitivity, specificity, PPV, NPV and diagnostic accuracy values of 67-100%, 85-100%, 83-100%, 84-100% and 84-100%, respectively, in recognising lesions located in different pelvic sites. CONCLUSIONS: MR imaging combined with colonography is a highly accurate tool for characterising deep endometriotic lesions in patients scheduled for laparoscopic surgery. In particular, MR colonography has very high accuracy in detecting colorectal involvement.

Study on the effectiveness of a nifedipine gel for treatment of Raynaud?s phenomenon.

The aim of this study is to evaluate the efficacy of a nifedipine gel in patients with primary or secondary Raynaud?s phenomenon. Photopletismography was the instrumental examination test used to evaluate recovery time (time necessary for recuperation of normal capillary circulation) in 17 patients with primary or secondary Raynaud?s phenomenon before and after the application of the gel. It emerged that of the 17 patients who used the gel, in 3 cases the recovery time was reduced, in 9 cases the recovery time was cancelled (no spasm occurred), in 5 cases the recovery time was not modified. Therefore, in more than 70 percent of patients the drug had a positive effect. Besides, 50 percent of the patients referred an improvement of the subjective symptomatology with reduction of cooling, torpidity, ache and paresthesias of the fingers. The results obtained, even if related to a restricted number of patients and to a brief interval of time, show the effectiveness of this drug in patients with primary or secondary Raynaud?s phenomenon. We believe that these results, presented here for the first time, are important for investigators involved in the study of Raynaud?s disease.