The contribution and histopathological correlation of MRI in BI-RADS category 4 solid lesions detected by ultrasonography

Abstract

Background/Aim: BI-RADS category 4 breast lesions have widely varying malignancy rates and they are almost always evaluated with biopsy. However, especially in the 4a subgroup with a benign character of up to 98%, many patients undergo unnecessary invasive procedures. Breast MRI can be a good problem-solving method to reduce unnecessary invasive procedures, but there are very few publications on BI-RADS category 4 solid lesions. This study aimed to investigate the contribution of breast MRI in Breast Imaging Reporting and Data System (BI-RADS) category 4 solid mass lesions detected by Mammography and Ultrasonography. Methods: In this retrospective cohort study, ultrasound reports of patients examined in the radiology breast imaging unit between January 2015 and December 2017 were reviewed. Cases reported as BI-RADS category 4 with a solid mass on ultrasonography were determined. Patients without histopathological diagnosis and/or breast MRI were excluded from the study. After the implementation of the exclusion criteria, 121 solid lesions of 104 female patients were included in the study. US and MRI images of the patients were re-evaluated by two radiologists and BI-RADS scoring was performed again. The obtained data were analyzed statistically together with histopathological data. Results: With breast MRI, 74 of 121 BI-RADS category 4 lesions were downgraded while 13 lesions were upgraded. Of the 74 downgraded lesions, 61 were BI-RADS category 2 and 3, which do not require a biopsy. Only one of these lesions was histopathologically malignant. Of the 13 lesions upgraded, 6 were in BI-RADS category 5, two of which were benign. The sensitivity, specificity, positive and negative predictive values of MRI were 93.8%, 56.2%, 24.6%, and 98.3%, respectively. Conclusion: In our study, breast MRI reduced the BI-RADS categories to 2 and 3 in approximately half of the BI-RADS category 4 solid lesions detected by ultrasound. Therefore, problem-solving MRI may be useful to avoid unnecessary invasive procedures in these patients.