Impact of Background Parenchymal Enhancement on Breast MRI Lesion Detection

Overview

Background parenchymal enhancement (BPE) on breast MRI varies with hormonal and physiological factors and may affect lesion detection. This systematic review analyzed the influence of BPE levels on the identification and diagnostic accuracy of enhancing breast lesions using a region-of-interest (ROI) based approach.

Background

Dynamic contrast-enhanced MRI (DCE-MRI) is highly sensitive for breast cancer detection but is affected by background parenchymal enhancement (BPE), which represents normal breast tissue enhancement after contrast administration. BPE varies with menstrual cycle, hormone levels, and vascular factors and is categorized by the ACR BI-RADS lexicon into minimal, mild, moderate, or marked. While BPE can mimic or mask lesions, its exact impact on diagnostic accuracy remains controversial, with some studies showing increased abnormal interpretations but no significant effect on final diagnosis, and others indicating a direct relationship between BPE and diagnostic performance.

Data Highlights

The study included women undergoing breast MRI between May 2020 and September 2023, excluding those with renal insufficiency, allergy to gadolinium, prior chemotherapy or antihormonal treatment, pregnancy, or breastfeeding. MRI was performed on 1.5-T or 3-T scanners with standardized protocols. Two readers independently assessed BPE levels and lesion localization within 10 predefined volumetric ROIs per patient. BPE was classified according to ACR BI-RADS categories on early postcontrast images. Diagnostic accuracy was evaluated regionally, requiring correct lesion localization and classification.

Key Findings

• BPE is influenced by hormonal status and vascular factors, showing variable enhancement patterns that can be peripheral, central, nodular, regional, or diffuse.
• Higher BPE levels (moderate to marked) are associated with increased abnormal interpretation rates but do not consistently reduce final diagnostic accuracy.
• ROI-based analysis allows lesion-level assessment, accounting for coexistence of benign and malignant findings within the same patient.
• Readers blinded to clinical and histopathological data assessed BPE and lesion presence with standardized criteria, enhancing reproducibility.
• The study supports that BPE assessment should be integrated into breast MRI interpretation to contextualize lesion detection and reduce false positives.

Clinical Implications

Clinicians should consider BPE levels when interpreting breast MRI, as moderate to marked BPE may increase false-positive findings but does not necessarily compromise diagnostic accuracy. Incorporating standardized BPE assessment and ROI-based lesion localization can improve diagnostic confidence and patient management decisions. Awareness of BPE variability related to hormonal status can guide optimal timing of MRI examinations.

Conclusion

Background parenchymal enhancement significantly influences the interpretation of breast MRI by potentially masking or mimicking lesions. A standardized, ROI-based approach to lesion detection that accounts for BPE can enhance diagnostic accuracy and clinical decision-making.

References

1. American College of Radiology (ACR) BI-RADS® MRI Lexicon
2. Obuchowski et al. 2010 -- Region-based analysis framework for breast MRI