Objective: Evaluating concordance between core biopsy results and imaging findings is an integral component of breast intervention. Pathologic results deemed benign discordant reflect concern that a malignancy may have been incorrectly sampled. Standard of care currently is surgical excision, although a large percentage of these lesions will be benign at final pathologic analysis. The purpose of this study was to determine whether inclusion of contrast-enhanced MRI would optimize patient care.
Materials and methods: Forty-five patients with 46 lesions were identified who underwent contrast-enhanced MRI after receiving discordant ultrasound or stereotactic biopsy results between 2012 and mid 2018. These findings were classified BI-RADS category 4 at diagnostic imaging. Disease-positive was defined as all malignancies and borderline lesions.
Results: Fourteen patients had suspicious MRI findings; 31 patients did not. Negative or benign MRI findings were validated by stability at imaging follow-up of at least 1 year in 27 patients (28 lesions) and at least 6 months in four patients. Eight of the total of 46 discordant lesions were ultimately malignant, a rate of 17.3%, an expected result for BI-RADS 4 lesions. Sensitivity, specificity, positive predictive value, and negative predictive value of MRI calculated in the group of 41 patients (42 lesions) with documented stability for at least 1 year were 100%, 93.3%, 85.7%, and 100%. The false-negative rate of MRI was 0%; the false-positive rate was 2 of 30 (6.7%).
Conclusion: In the management of discordant benign core biopsy results, contrast-enhanced MRI facilitated successful triage of patients to surgery; 31 of the original 45 patients (68.9%) avoided surgery.
Keywords: breast imaging; contrast-enhanced MRI; discordant core biopsy.