ORIGINAL RESEARCH n BREAST IMAGING Radiology: Volume 281: Number 2—November 2016 n radiology.rsna.org 373 1 From the Departments of Circulation and Medical Imaging (J.R.T., T.E.S., T.F.B.), Physics (P.E.G), and Cancer Research and Molecular Medicine (H.E.F.), Faculty of Medicine, Norwegian University of Science and Technology (NTNU), PO Box 8905, 7491 Trondheim, Norway; and Department of Surgery (H.E.F.), and Clinic of Radiology and Nuclear Medicine (J.R.T., P.E.G., A.Ø.), St. Olav’s University Hospital, Trondheim, Norway. Received July 29, 2015; revision requested September 17 and received January 8, 2016; accepted February 11; final version accepted February 25. Address correspondence to J.R.T. (e-mail: jose.teruel@ ntnu.no). Supported by grants from the Liaison Committee between the Central Norway Regional Health Authority (RHA) and the Norwegian University of Science and Technology (NTNU). q RSNA, 2016 Purpose: To evaluate the relative change of the apparent diffusion coefficient (ADC) at low- and medium-b-value regimens as a surrogate marker of microcirculation, to study its correlation with dynamic contrast agent–enhanced (DCE) magnetic resonance (MR) imaging–derived parameters, and to assess its potential for differentiation between ma- lignant and benign breast tumors. Materials and Methods: Ethics approval and informed consent were obtained. From May 2013 to June 2015, 61 patients diagnosed with either malignant or benign breast tumors were prospec- tively recruited. All patients were scanned with a 3-T MR imager, including diffusion-weighted imaging (DWI) and DCE MR imaging. Parametric analysis of DWI and DCE MR imaging was performed, including a proposed marker, relative enhanced diffusivity (RED). Spearman correlation was calculated between DCE MR imaging and DWI pa- rameters, and the potential of the different DWI-derived parameters for differentiation between malignant and be- nign breast tumors was analyzed by dividing the sample into equally sized training and test sets. Optimal cut-off values were determined with receiver operating charac- teristic curve analysis in the training set, which were then used to evaluate the independent test set. Results: RED had a Spearman rank correlation of 0.61 with the initial area under the curve calculated from DCE MR im- aging. Furthermore, RED differentiated cancers from be- nign tumors with an overall accuracy of 90% (27 of 30) on the test set with 88.2% (15 of 17) sensitivity and 92.3% (12 of 13) specificity. Conclusion: This study presents promising results introducing a sim- plified approach to assess results from a DWI protocol sensitive to the intravoxel incoherent motion effect by us- ing only three b values. This approach could potentially aid in the differentiation, characterization, and monitor- ing of breast pathologies. q RSNA, 2016 Online supplemental material is available for this article. Jose R. Teruel, PhD Pål E. Goa, PhD Torill E. Sjøbakk, PhD Agnes Østlie, MD Hans E. Fjøsne, MD, PhD Tone F. Bathen, PhD A Simplified Approach to Measure the Effect of the Microvasculature in Diffusion- weighted MR Imaging Applied to Breast Tumors: Preliminary Results 1 This copy is for personal use only. To order printed copies, contact reprints@rsna.org