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

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 3.0 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.