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