DIAGNOSTIC ACCURACY OF ULTRASOUND BI-RADS CATEGORIES 4 AND 5 FOR BREAST CANCER DETECTION

Abstract

Background: Breast cancer is the most frequently diagnosed malignancy and a leading cause of cancer-related mortality among women worldwide, with a disproportionately heavy burden in Pakistan. Ultrasound BI-RADS categories 4 and 5 are the thresholds at which tissue biopsy is recommended, yet local data describing the diagnostic performance of these categories against histopathology remain scarce.

Methods: This cross-sectional diagnostic accuracy study was conducted in the Departments of Radiology at Nishtar Medical University and Bakhtawar Amin Medical and Dental College, Multan, over four months from May 2026 to Sep 2026. 105 women aged 14–80 years with clinically suspected breast lesions were enrolled by purposive sampling. All underwent high-resolution ultrasound (5–10 MHz linear probe), BI-RADS categorisation, and subsequent core-needle or excisional biopsy. Histopathology served as the reference standard. Diagnostic accuracy indices were derived from a 2×2 contingency table in which BI-RADS 4/5 was taken as test-positive and BI-RADS 2/3 as test-negative.

Results: Among 105 women (mean age 34.17 ± 11.34 years), histopathology confirmed malignancy in 52 (49.5%) and benign disease in 53 (50.5%). BI-RADS 4/5 was assigned to 56 women (53.3%) and BI-RADS 2/3 to 49 (46.7%); malignancy rates were 0% in BI-RADS 2, 12.5% in 3, 53.8% in 4A and 100% in 4B, 4C and 5. Ultrasound BI-RADS 4/5 achieved a sensitivity of 96.15% (95% CI 87.02–98.94), specificity of 88.68% (95% CI 77.42–94.71), positive predictive value of 89.29% (95% CI 78.53–95.00), negative predictive value of 95.92% (95% CI 86.29–98.87), and overall diagnostic accuracy of 92.38% (95% CI 85.68–96.09).

Conclusion: Ultrasound BI-RADS categories 4 and 5 show excellent diagnostic accuracy for discriminating benign from malignant breast lesions and can dependably guide biopsy decisions, although histopathology remains the definitive diagnostic standard.