Ultrasound real-time elastography can predict malignancy in BI-RADS®-US 3 lesions

Background: Lesions of the breast that are classified BI-RADS (R)-US 3 by ultrasound are probably benign and observation is recommended, although malignancy may occasionally occur. In our study, we focus exclusively on BI-RADS (R)-US 3 lesions and hypothesize that sonoelastography as an adjunct to conventional ultrasound can identify a high-risk-group and a low-risk-group within these patients. Methods: A group of 177 breast lesions that were classified BI-RADS (R)-US 3 were additionally examined with real-time sonoelastography. Elastograms were evaluated according to the Tsukuba Elasticity Score. Pretest and posttest probability of disease (POD), sensitivity (SE), specificity (SP), positive (PPV) and negative predictive values (NPV) and likelihood-ratios (LR) were calculated. Furthermore, we analyzed the false-negative and false-positive cases and performed a model calculation to determine how elastography could affect the proceedings in population screening. Results: In our collection of BI-RADS (R)-US 3 cases there were 169 benign and eight malignant lesions. The pretest POD was 4.5% (95% confidence interval (CI): 2.1-9.0). In patients with a suspicious elastogram (high-risk group), the posttest POD was significantly higher (13.2%, p = 0.041) and the positive LR was 3.2 (95% CI: 1.7-5.9). With a benign elastogram (low-risk group), the posttest POD decreased to 2.2%. SE, SP, PPV and NPV for sonoelastography in BI-RADS (R)-US 3 lesions were 62.5% (95% CI: 25.9-89.8), 80.5% (95% CI: 73.5-86.0), 13.2% (95% CI: 5.0-28.9) and 97.8% (95% CI: 93.3-99.4), respectively. Conclusions: Sonoelastography yields additional diagnostic information in the evaluation of BI-RADS (R)-US 3 lesions of the breast. The examiner can identify a low-risk group that can be vigilantly observed and a high-risk group that should receive immediate biopsy due to an elevated breast cancer risk.