Positive and negative predictive values of BI-RADS-MRI descriptors for focal breast masses

The purposes of this study were to evaluate the positive and negative predictive values of the BI-RADS-MR descriptors of focal masses and to develop an interpretation model based on the kinetic and morphologic parameters.

Retrospective review was performed of 171 consecutive focal breast masses. MR imaging was performed on a 1.5T system using the volumetric interpolated breath-hold examination sequence (mean partition thickness, 1.2 mm; time of acquisition, 35 s). Kinetic enhancement patterns were assessed by visually comparing signal intensity on the dynamic images acquired at 60 s and 4 min (washout, plateau, and persistent).

There were 126 malignant and 45 benign lesions. The most frequent morphological finding among the malignant lesions was heterogeneous internal enhancement in the delayed phase (96%; P<0.001); the most frequent finding in benign lesions was smooth margin or smooth shape/margin (80 to 82%; P<0.001). The features with the highest positive predictive value for carcinoma were spiculated margin (100%), delayed central enhancement (100%), delayed enhancing internal septations (97%), and irregular shape (97%). The characteristics with the highest diagnostic accuracy for malignancy were spiculated margin (100%) and heterogeneous enhancement following washout in the smooth shape/margin group (100%). The sensitivity, specificity, and positive and negative predictive values of an interpretation model based on a combination of the morphologic characteristics and kinetic information were 99%, 89%, 96%, and 98%, respectively.

A combination of morphologic criteria, particularly lesion shape/margin and internal heterogeneity, and kinetic information is useful for differentiating benign and malignant lesions.