Diffusion-Weighted Whole-Body Imaging with Background Body Signal Suppression (DWIBS)-Based Non-Contrast Breast MRI Screening: Initial Real-World Outcomes of a Non-Population-Based Program

Background/Objectives: Mammography screening is limited by low sensitivity in dense breasts and by low participation, partly because of compression-related pain. We report the initial real-world outcomes of a non-population-based (opportunistic), non-contrast, compression-free breast cancer screening program based on DWIBS (DWIBS-BCS), distinguishing initial (prevalence) from subsequent screening. Methods: We retrospectively analyzed DWIBS-BCS examinations performed at a single center from January 2021 to December 2023, excluding examinations in women reporting a palpable lump. Two radiologists assigned four categories; category D was referred for diagnostic follow-up, and categories A–C were not systematically verified. Recall rate (RR), diagnostic follow-up completion rate (DFR), cancer detection rate (CDR), and positive predictive value (PPV) were calculated per examination with exact 95% confidence intervals (CIs) for initial, subsequent, and overall screening. Results: Of 554 DWIBS-BCS examinations, 506 were eligible: 360 initial (360 women) and 146 subsequent (107 women). All six screen-detected cancers occurred at initial screening. At initial screening, RR was 6.1% (22/360; 95% CI, 3.9–9.1%), DFR 81.8% (18/22; 95% CI, 59.7–94.8%), CDR 1.7% (6/360; 16.7 per 1000 examinations; 95% CI, 0.6–3.6%), and PPV 33.3% (6/18; 95% CI, 13.3–59.0%). No cancer was detected among 146 subsequent examinations. Five of the six screen-detected cancers were clinical stage 0 or I. In 36.8% (186/506) of examinations, the woman had never had mammography. Conclusions: In this self-selected cohort with incomplete outcome ascertainment, DWIBS-BCS detected six mostly early-stage cancers at initial screening. These preliminary, descriptive data are not comparable with organized-screening benchmarks and do not establish screening accuracy or clinical benefit; prospective studies with systematic outcome ascertainment are needed.