Multimodal apparent diffusion MRI model in noninvasive evaluation of breast cancer and Ki-67 expression

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 3.0 T MRI scanner with 16 b values. The MAD parameters, as flow (f_F, D_F), unimpeded (fluid) (f_UI), hindered (f_H, D_H, and α_H), and restricted (f_R, D_R), 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 f_R in the malignant lesions was significantly higher than in the benign lesions (P = 0.001), whereas the f_UI and D_H 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 (f_R, D_H, and f_UI) provided the highest AUC (0.851). 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 D_H, higher D_F and higher α_H (P < 0.05). The combination parameters of D_H, D_F, and α_H 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.