• Hubert Bickel, Stephan H Polanec, Georg Wengert, Katja Pinker, Wolfgang Bogner, Thomas H Helbich, and Pascal A Baltzer.
• Department of Biomedical Imaging and Image Guided Therapy, Division of Molecular and Gender Imaging, Medical University of Vienna, Austria.
• J Magn Reson Imaging. 2019 Dec 1; 50 (6): 1754-1761.

BackgroundDiffusion-weighted imaging (DWI) is an MRI technique with the potential to serve as an unenhanced breast cancer detection tool. Synthetic b-values produce images with high diffusion weighting to suppress residual background signal, while avoiding additional measurement times and reducing artifacts.PurposeTo compare acquired DWI images (at b = 850 s/mm2 ) and different synthetic b-values (at b = 1000-2000 s/mm2 ) in terms of lesion visibility, image quality, and tumor-to-tissue contrast in patients with malignant breast tumors.Study TypeRetrospective.PopulationFifty-three females with malignant breast lesions.Field Strength/SequenceT2 w, DWI EPI with STIR fat-suppression, and dynamic contrast-enhanced T1 w at 3T.AssessmentFrom acquired images using b-values of 50 and 850 s/mm2 , synthetic images were calculated at b = 1000, 1200, 1400, 1600, 1800, and 2000 s/mm2 . Four readers independently rated image quality, lesion visibility, preferred b-value, as well as the lowest and highest b-value, over the range of b-values tested, to provide a diagnostic image.Statistical TestsMedians and mean ranks were calculated and compared using the Friedman test and Wilcoxon signed-rank test. Reproducibility was analyzed by intraclass correlation (ICC), Fleiss, and Cohen's κ.ResultsRelative signal-to-noise and contrast-to-noise ratios decreased with increasing b-values, while the signal-intensity ratio between tumor and tissue increased significantly (P < 0.001). Intermediate b-values (1200-1800 s/mm2 ) were rated best concerning image quality and lesion visibility; the preferred b-value mostly lay at 1200-1600 s/mm2 . Lowest and highest acceptable b-values were 850 s/mm2 and 2000 s/mm2 . Interreader agreement was moderate to high concerning image quality (ICC: 0.50-0.67) and lesion visibility (0.70-0.93), but poor concerning preferred and acceptable b-values (κ = 0.032-0.446).Data ConclusionSynthetically increased b-values may be a way to improve tumor-to-tissue contrast, lesion visibility, and image quality of breast DWI, while avoiding the disadvantages of performing DWI at very high b-values.Level Of Evidence3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1754-1761.© 2019 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

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