Background: Background parenchymal enhancement (BPE) on breast Magnetic Resonance Imaging (MRI) is the amount of enhancing fibroglandular tissue, BPE influences both MRI interpretation and possibly risk of breast cancer. If increased BPE proves to be an important risk factor, then it has the potential to serve as a bio-marker of breast cancer risk.Before BPE can be introduced into clinical practice, data confirming the repeatability and reproducibility of its measurement is required. . PURPOSE The aim of this study is to assess repeatability and reproducibility of BPE measurements by expert and non expert breast radiologists. Material and Method: BPE measurements were made retrospectively on a consecutive series of 51 clinically indicated MRI’sperformed. All examinations were independently assessed for BPE by two expert readers and an inexperienced reader and assigned a category 1-4 in accordance with the proposed BIRADS MRI categorisation. Results: The inter-reader agreement between expert readers obtained was substantial (k=0.75 p< 0,01). Agreement between expert and non expert readers was moderate (k=0,494 p< 0,01 and k=0,55 p< 0,01). The intra-reader agreement between the three readers was strong (ICC 0.94). The intra-reader agreement for the expert readers was substantial (k=0.78 k=0.68 p< 0,01). Conclusion: Our results show a high intra and inter-reader reproducibility, between expert readers. Lower reproducibility for non-expert radiologists suggests the presence of a learning curve and training requirements for categorization of BPE.
