(Elastography) E-BI-RADS: A Novel Classification System for Breast Elastography to Enable Safe Biopsy De-escalation

OBJECTIVES: Determining the probability of malignancy of a breast lesion allows for the appropriate triage of follow-up. Although BI-RADS provides standardized risk stratification for mammography, ultrasound, and magnetic resonance imaging, no equivalent classification system exists for breast elastography. The aim of this study was to develop and evaluate a data-driven E-BI-RADS classification for breast elastography and to compare its diagnostic performance with B-mode BI-RADS. MATERIALS AND METHODS: In this retrospective study, consecutive patients undergoing breast imaging with available B-mode ultrasound, shear-wave elastography (SWE), and strain elastography (10L4 transducer, Siemens ACUSON Sequoia) from 06/2023 to 12/2025 were included. A multivariable logistic regression model combining SWE velocity and elastography-to-B-mode lesion size (E/B) ratio was used to estimate malignancy probability, followed by Platt recalibration. Data-driven probability cutoffs were derived to define E-BI-RADS categories aligned with the BI-RADS concept. (E-)BI-RADS categories 4 and 5 were considered an indication for biopsy. Histopathologic evaluation or imaging follow-up served as the reference standard. RESULTS: The cohort comprised 344 breast lesions in 337 patients, including 224 (65.1%) malignant and 120 (34.9%) benign lesions. B-mode BI-RADS achieved a sensitivity of 98.6% (221/224) and a specificity of 34.2% (41/120). E-BI-RADS demonstrated malignancy rates of 0.0% in E-BI-RADS 2 (0/71); 5.3% in E-BI-RADS 3 (1/19); 85.2% in E-BI-RADS 4 (155/182); and 94.4% in E-BI-RADS 5 (68/70). E-BI-RADS achieved a sensitivity of 99.6% (223/224) and a specificity of 74.2% (89/120). The single false-negative case was a 31 mm B-cell lymphoma, classified as E-BI-RADS 3, with a shear-wave velocity of 4.4 m/s and an E/B ratio of 0.9. Decision-curve analysis demonstrates that E-BI-RADS achieves higher net benefit than SWE-based and B-mode BI-RADS strategies. DISCUSSION: E-BI-RADS provides the first standardized, BI-RADS-like classification system for breast elastography and enables safe biopsy de-escalation with excellent sensitivity and improved specificity compared with existing approaches.