Diagnostic Accuracy of Sonomammography in Differentiation of BI-RADS 4 Suspicious Breast Lesions as Benign or Malignant Keeping Histopathology as Gold Standard

Diagnostic Accuracy of Sonomammography for BI-RADS 4 Breast Lesions

Abstract

Background:  Breast cancer continues to be the most prevalent malignancy among women worldwide, with an estimated 2.3 million new cases and 685,000 fatalities reported in 2020. In a population of 220 million, Pakistan alone reported approximately 178,000 new cancer cases and 117,149 fatalities. Early detection through imaging is essential for enhancing survival outcomes. Although mammography is the standard screening method, its diagnostic efficacy deteriorates in women with dense breast tissue. In such instances, sonomammography, a real-time imaging technique that is radiation-free, provides a more accurate characterization of the lesion. Nevertheless, its diagnostic potential for BI-RADS 4 (suspicious) lesions is still underexplored in local environments.

Objective: To assess the diagnostic accuracy of sonomammography in distinguishing benign from malignant BI-RADS 4 lesions, with histopathology serving as the reference standard.

Methods: A cross-sectional investigation was conducted at the Department of Radiology, CMH Lahore, involving 360 women aged 30–70 years who had sonographically detected BI-RADS 4 lesions. All participants underwent high-frequency linear-array ultrasound (≥10 MHz), which was followed by an ultrasound-guided core biopsy for histopathological confirmation. Sonographic findings were classified as low suspicion (BI-RADS 4A) or moderate/high suspicion (BI-RADS 4B/4C). The diagnostic performance measures—sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy—were computed.

Results: The prevalence of malignancy was 60.6% among the 360 women. A total of 207 true positives and 128 true negatives were identified by sonomammography, with 11 false negatives and 14 false positives. The sensitivity was 95.0%, the specificity was 90.1%, the PPV was 93.7%, the NPV was 92.1%, and the overall accuracy was 93.1%. These results are in close agreement with previous regional data that reported diagnostic indices that were similar.

Conclusion: In dense breasts, sonomammography exhibits high diagnostic accuracy in the evaluation of BI-RADS 4 lesions, particularly in the differentiation of malignant from benign pathology. When employed as a complementary imaging modality to mammography, it can effectively decrease the number of superfluous biopsies. It is advised that additional large-scale and multicenter studies be conducted to verify these findings and refine the BI-RADS subcategorization in ultrasound diagnostics.