Background parenchymal enhancement over exam time in patients with and without breast cancer

Abstract

Purpose: To compare background parenchymal enhancement (BPE) over time in patients with and without breast cancer. Materials and Methods: This retrospective Institutional Review Board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant study included 116 women (25–84 years, mean 54 years) with breast cancer who underwent breast magnetic resonance imaging at 3T between 1/2/2009 and 12/29/2009 and 116 age and date-of-exam-matched women without breast cancer (23–84 years, mean 51 years). Two independent, blinded readers (R1, R2) recorded BPE (minimal, mild, moderate, marked) at three times (100, 210, and 320 seconds postcontrast). Subsequent cancers were diagnosed in 9/96 control patients with follow up (12.6–93.0 months, mean 63.6 months). Exact Mann–Whitney, Fisher's exact, and McNemar tests were performed. Results: Mean BPE was not found to be different between patients with and without breast cancer at any time (P = 0.36–0.64). At time 2 as compared with time 1, there were significantly more patients, both with and without breast cancer, with BPE >minimal (R1: 90 vs. 41 [P < 0.001] and 81 vs. 36 [P < 0.001]; R2: 84 vs. 52 [P < 0.001] and 79 vs. 43 [P < 0.001]) and BPE >mild (R1: 59 vs. 10 [P < 0.001] and 47 vs. 13 [P < 0.001]; R2: 49 vs. 12 [P < 0.001] and 41 vs. 18 [P < 0.001]). BPE changes between times 2 and 3 were not significant (P = 0.083–1.0). Odds ratios for control patients developing breast cancer were significant only for R2 and ranged up to 7.67 (1.49, 39.5; P < 0.01) for BPE >mild at time 2. Conclusion: BPE changes between the first and second postcontrast scans and stabilizes thereafter in most patients. Further investigation into the most clinically relevant timepoint for BPE assessment is warranted. Level of Evidence: 3. J. Magn. Reson. Imaging 2017;45:74–83.