Multimodal apparent diffusion weighted MRI analysis in noninvasive assessment of breast cancer malignancy and Ki-67 status

Abstract Background: To assess the capability of multimodal apparent diffusion (MAD) weighted magnetic resonance imaging (MRI) to distinguish between malignant and benign breast lesions, and to predict Ki-67 expression level in breast cancer. Methods: This retrospective study was conducted with 93 patients who had postoperative pathology-confirmed breast cancer or benign breast lesions. MAD images were acquired using a 3.0T MRI scanner with 16 b values. The MAD parameters, as flow (fF, DF), unimpeded (fluid) (fI), hindered (fH, DH, and αH), and restricted (fR, DR), were calculated. The differences of the parameters were compared by Mann-Whitney U test between the benign/malignant lesions and high/low Ki-67 expression level. The diagnostic performance was assessed by the area under the receiver operating characteristic curve (AUC). Results: The fR in the malignant lesions was significantly higher than in the benign lesions (P=0.001), whereas the fI and DH were found to be significantly lower (P=0.007 and P<0.001, respectively). Compared with individual parameter in differentiating malignant from benign breast lesions, the combination parameters of MAD (fR, DH, and fI) provided the highest AUC (0.851), with the highest specificity (88.9%) and accuracy (86.6%). Of the 73 malignant lesions, 42 (57.5%) were assessed as Ki-67 low expression and 31 (42.5%) were Ki-67 high expression. The Ki-67 high status showed lower DH, higher DF and higher αH (P<0.05). The combination parameters of DH, DF, and αH provided the highest AUC (0.691) for evaluating Ki-67 expression level. Conclusions: MAD weighted MRI is a useful method for the breast lesions diagnostics and the preoperative prediction of Ki-67 expression level.