Preoperative histogram parameters of dynamic contrast‐enhanced MRI as a potential imaging biomarker for assessing the expression of Ki‐67 in prostate cancer

PURPOSE: To investigate whether preoperative histogram parameters of dynamic contrast‐enhanced MRI (DCE‐MRI) can assess the expression of Ki‐67 in prostate cancer (PCa). MATERIALS AND METHODS: A consecutive series of 76 patients with pathology‐proven PCa who underwent routine DCE‐MRI scans were retrospectively recruited. Quantitative parameters including the volume transfer constant (K(trans)), rate contrast (K(ep)), extracellular‐extravascular volume fraction (V(e)), and plasma volume (V(p)) by outlining the three‐dimensional volume of interest (VOI) of all lesions were processed. Then, the histogram analyses of these quantitative parameters were performed. The Spearman rank correlation analysis was used to evaluate the correlation of these parameters and Ki‐67 expression of PCa. Receiver operating characteristic (ROC) curve analysis was adopted to evaluate the efficacy of these quantitative histogram parameters in identifying high Ki‐67 expression from low Ki‐67 expression of PCa. RESULTS: Eighty‐eight PCa lesions were enrolled in this study, including 31 lesions with high Ki‐67 expression and 57 lesions with low Ki‐67 expression. The median, mean, 75th percentile, and 90th percentile derived from K(trans) and K(ep) had a moderately positive correlation with Ki‐67 expression (r = 0.361–0.450, p < 0.05), in which both the median and mean of K(trans) had the highest positive correlation (r = 0.450, p < 0.05). The diagnostic efficacy of the K(trans) median, mean, 75th percentile, and 90th percentile, along with the K(ep)‐based median and mean was assessed by the ROC curve. The area under the curve (AUC) of the mean for K(trans) was the highest (0.826). When the cut‐off of the mean for K(trans) was ≥0.47/min, its Youden index, sensitivity, and specificity were 0.625, 0.871, and 0.754, respectively. The AUC of the median of K(ep) was the lowest (0.772). CONCLUSION: The histogram of DCE‐MRI quantitative parameters is correlated with Ki‐67 expression, which has the potential to noninvasively assess the expression of Ki‐67 with patients of PCa.