Abstract P4-03-06: Non-invasive classification of microcalcifications by the use of X-ray phase contrast mammography as a novel tool in breast diagnostics

Abstract

Purpose: Phase-contrast and scattering-based x-ray imaging are known to provide additional and complementary information to conventional, absorption-based methods. The goal of this study is to evaluate this method to distinguish between benign and malignant microcalcifications with the benefit to increase accuracy of early breast cancer diagnosis. Phase-contrast mammography has been shown to increase image quality of native breast samples when compared to conventional mammography. Two major types of microcalcifications are found within breast tissue. Type I consist of calcium oxalate dehydrate and type II microcalcifications are composed of calcium phosphates. Type I is seen most frequently in benign lesions whereas type II is indicative for proliferative lesions, including carcinomas. Phase contrast mammography is shown here to distinguish between the two types of microcalcifications and therefore indicates a step forward to improve early breast cancer diagnosis. Material and Methods: Freshly dissected breast specimens (n = 50) were imaged using a Talbot-Lau interferometer equipped with a conventional x-ray tube; the interferometer was operated at the fifth Talbot distance, tube voltage of 40 kVp with mean energy of 28 keV, and current of 25 mA. The device simultaneously recorded absorption, differential phase and small-angle scattering signals. These quantities were combined into novel, high-frequency-enhanced radiographic images. Histopathological analysis was performed and regions of interests correlated with the findings of phase contrast mammography. Results: Our novel imaging approach yields complementary and otherwise inaccessible information on electron density distribution and small-angle scattering power of the sample at microscopic scale. Recently we generated the world's first phase contrast mammograms of native, not-fixed human whole breast samples. Our results indicate the superiority of the new technique with respect to image quality and lesion conspicuity. A clinical reader study is currently carried out. Exploiting the multiple, complementary information obtained by grating-based interferometry, we are able to classify microcalcifications by a non-invasive technique within the clinical environment. By considering the small-angle scattering signal as a complement to the absorption signal, our method can analyze the differences in the attenuation coefficient as well as in the crystal structure of the microcalcifications. Further, the scattering signal is used to decouple the thickness parameter. We demonstrate that type I and type II microcalcifications give opposite absorption and scattering signals and in addition the small-angle scattering signal helps to determine the type of microcalcification. Conclusions: The potential clinical significance of phase-contrast enhanced mammography has been evaluated by our team. This technique yields improved diagnostic capabilities when compared with conventional mammography, can provide superior contrast, inaccessible and complementary information, and potentially also reduce dose deposition. The non-invasive classification of microcalcifications is an important step toward early diagnosis and differentiation of breast lesions. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-06.