More than interobserver agreement is required for comparisons of categorization systems

Positive Predictive Value for the Malignancy of Mammographic Abnormalities Based on the Presence of an Ultrasound Correlate

Purpose To compare the outcomes of different mammographic lesions based on the presence of an ultrasound (US) correlate and to estimate how often targeted US can identify such lesions.

Materials and Methods This retrospective study included all consecutive cases from 2010 to 2016, with Breast Imaging Reporting and Database System (BI-RADS) categories 4 & 5 who underwent US as part of their diagnostic workup. We compared the incidence of malignancy between lesions comprising a US correlate that underwent US-guided core needle biopsy (CNB) and those without a correlate that underwent stereotactic CNB.

Results 833 lesions met the study criteria and included masses (64.3%), architectural distortion (19%), asymmetries (4.6%), and calcifications (12.1%). The CNB-based positive predictive value (PPV) was higher for lesions with a US correlate than for those without (40.2% [36.1, 44.4%] vs. 18.9% [14.5, 23.9%], respectively) (p<0.001). Malignancy odds for masses, asymmetries, architectural distortion, and calcifications were greater by 2.70, 4.17, 4.98, and 2.77 times, respectively, for the US-guided CNB (p<0.001, p=0.091, p<0.001, and p=0.034, respectively). Targeted US identified a correlate to 66.3% of the mammographic findings. The odds of finding a correlate were greater for masses (77.8%) than architectural distortions (53.8%) (p<0.001) or calcifications (24.8%) (p<0.001).

Conclusion The success of targeted US in identifying a correlate varies significantly according to the type of mammographic lesion. The PPV of lesions with a US correlate was significantly higher than that of those with no correlate. However, the PPV of lesions with no US correlate is high enough (18.9%) to warrant a biopsy.