E.A. Krupinski (Ed.): IWDM 2008, LNCS 5116, pp. 67–73, 2008. © Springer-Verlag Berlin Heidelberg 2008 BIRADS Classification in Breast Tomosynthesis Compared to Mammography and Ultrasonography Anders Tingberg 1,2 , Ingvar Andersson 3 , Debra M Ikeda 4 , Mark Ruschin 2,5 , Tony Svahn 2 , and Pontus Timberg 2 1 Department of Radiation Physics, Malmö University Hospital, Malmö, Sweden 2 Department of Medical Radiation Physics, Lund University, Malmö University Hospital, Malmö, Sweden 3 Diagnostic Centre of Imaging and Functional Medicine, Malmö University Hospital, Malmö, Sweden 4 Department of Radiology, Stanford University, Stanford Advanced Medicine Center, Stanford, CA, USA 5 Department of Radiation Physics, University Health Network/Princess Margaret Hospital, Toronto, Ontario, Canada Abstract. This paper presents the Malmö Breast Tomosynthesis project. The tomosynthesis equipment is described as well as the patient selection and image acquisition. Special focus is given to one of the studies of the project, which is a comparison of the diagnostic performance between breast tomosynthesis (BT), digital mammography (DM) and ultrasonography (US): Tumor classification according to the BIRADS system was performed on 40 cancers imaged with DM, US and BT. The patients were selected on the basis of subtle signs of breast cancer on DM or negative findings on DM but suspicious lesions on US. The BIRADS scores based on the BT images were significantly higher than 1- view DM and 2-view DM, and equal to 2-view plus US. The results suggest that BT may be a suitable technique for breast cancer screening. Keywords: Breast tomosynthesis, mammography, ultrasonography, BIRADS classification. 1 Introduction 1.1 Tomosynthesis The background of the mammogram consists of normal breast structures superimposed onto a two-dimensional (2D) plane, comprising a so-called “anatomic background”. This may hamper cancer detection on mammograms. The anatomic background has been shown to play a larger role than quantum noise in the non-detection of certain lesion types and sizes (1-3). A tomographic technique like breast tomosynthesis (BT) that reduces the obscuring effect of overlying and underlying breast tissues should therefore improve sensitivity compared to digital mammography (DM) (4). Even though at least some studies suggest that this might be the case (3, 5), these results have been mostly based on phantom studies and limited clinical data.