Screening Mammography Interpretation Analysis Tool

Methodology & Frequently Asked Questions

What does this Screening Mammography Interpretation Analysis tool calculate?

The tool calculates two key screening performance metrics: the Abnormal Interpretation Rate (AIR), also known as recall rate, and Positive Predictive Value One (PPV1). Both are calculated from BI-RADS category counts and cancer detection data you enter, and are compared against BCSC national benchmarks.

What is the formula for AIR in this tool?

AIR (%) = (N0 + N3 + N4 + N5) / (N_negative + N0 + N3 + N4 + N5) × 100. Where N_negative is the count of BI-RADS 1 and 2 interpretations, and N0, N3, N4, N5 are the counts of each positive BI-RADS category. The BCSC benchmark range is 5%–12%.

What is PPV1 and how is it calculated?

PPV1 (Positive Predictive Value 1) is the proportion of recalled screening mammograms that resulted in a cancer diagnosis within one year. Formula: PPV1 (%) = True Positives / (True Positives + False Positives) × 100. The BCSC benchmark range is 3%–8%.

What is the difference between a True Positive and a False Positive in this context?

A True Positive is a recalled screening exam that led to a diagnosis of invasive breast cancer or DCIS within one year. A False Positive is a recalled exam where no cancer was found. All recalled patients fall into one of these two categories, so True Positives + False Positives should equal your total recalled count.

Why are BI-RADS 1 and 2 included but not counted in the recall rate?

BI-RADS 1 (Negative) and BI-RADS 2 (Benign) are negative screening interpretations — no additional evaluation is needed. They are included in the total interpretation count (denominator) but not in the positive/recalled count (numerator). This is consistent with the ACR BI-RADS audit framework and BCSC documentation.

Should BI-RADS 3 be used in screening mammography?

BI-RADS 3 (Probably Benign) at screening is generally discouraged by the ACR — ideally, patients with a finding appropriate for BI-RADS 3 at screening should undergo diagnostic evaluation before that assessment is assigned. However, it does occur in practice, and for audit purposes it is counted as a positive screening interpretation along with BI-RADS 0, 4, and 5.

Peer-Reviewed References

1. 1.Funaro K, et al. "Understanding the Mammography Audit." Radiologic Clinics of North America. 2021. View source
2. 2.Rosenberg RD, Yankaskas BC, Abraham LA, et al. "Performance Benchmarks for Screening Mammography." Radiology. 2006;241(1):55–66. View source
3. 3.Lehman CD, Arao RF, Sprague BL, et al. "National Performance Benchmarks for Modern Screening Digital Mammography: Update from the BCSC." Radiology. 2017;283(1):49–58. View source
4. 4.Lee CI, Abraham L, Miglioretti DL, et al. "National Performance Benchmarks for Screening Digital Breast Tomosynthesis: Update from the BCSC." Radiology. 2023;307(4):e222499. View source
5. 5.Sprague BL, Miglioretti DL, Lee CI, et al. "New mammography screening performance metrics based on the entire screening episode." Cancer. 2020;126(14):3289–3296. View source
6. 6.BCSC Screening Performance Benchmarks. Breast Cancer Surveillance Consortium. View source