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International Interobserver Variability of Breast Density Assessment
Leah H Portnow1, Lina Choridah2, Kardinah Kardinah3
1Division of Breast Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts; and Instructor, Department of Radiology, Harvard Medical School, Boston, Massachusetts.
Summary
Radiologists worldwide show high agreement in breast density assessment using BI-RADS categories. However, significant variability exists in the distribution of density categories across different global locations.
Area of Science:
- Radiology
- Medical Imaging
- Oncology
Background:
- Mammographic breast density is a key factor in breast cancer risk assessment.
- Standardized categorization of breast density is crucial for consistent interpretation and risk stratification.
Purpose of the Study:
- To evaluate interreader agreement and variability in mammographic breast density categorization among radiologists globally.
- To assess consistency in applying the BI-RADS density classification system across different countries.
Main Methods:
- Retrospective review of 800 2-D digital screening mammograms from Indonesia, the Netherlands, South Africa, and the US.
- Consensus density assessments by three radiologists per location using BI-RADS categories.
- Statistical analysis including Gwet's AC2, AC1, Stuart-Maxwell, McNemar tests, and conditional logistic regression.
Main Results:
- High interreader agreement (AC2=0.86) for four density categories and substantial agreement (AC1=0.66) for binary dense vs. not dense categories.
- Statistically significant differences (P < .001) in density distribution across the four categories among different reader teams.
- Majority of mammograms were categorized as scattered or heterogeneous density by all readers.
Conclusions:
- While radiologists achieve high interreader agreement in BI-RADS density categorization, statistically significant variability in density distribution persists across global locations.
- This variability highlights the need for further standardization or training to ensure consistent application of breast density assessments worldwide.
