Diffusion Kurtosis Imaging for Differentiating Borderline From Malignant Epithelial Ovarian Tumors: A Correlation With Ki-67 Expression

Purpose: To investigate the use of diffusion kurtosis imaging (DKI) in differentiating borderline from malignant epithelial ovarian tumors (MEOTs) and to correlate DKI parameters with Ki-67 expression. Materials and Methods: Fifty-two consecutive patients with epithelial ovarian tumors (17 borderline epithelial ovarian tumors, BEOTs; 35 MEOTs) were prospectively evaluated using DKI with b values of 0, 500, 1000, 1500, 2000, and 2500 s/ mm 2 and standard diffusion-weighted imaging (DWI) with b values of 0 and 1000 s/ mm 2 using a 1.5T magnetic resonance imaging (MRI) unit. The kurtosis (K) and diffusion coefficient (D) from DKI and apparent diffusion coefficient (ADC) from standard DWI were measured, compared, and correlated with Ki-67 expression between the two groups. Statistical analyses were performed using theMann-Whitney U-test, receiver operating characteristic (ROC) curves, and Spearman's correlation. Results: The K value was significantly lower in BEOTs than in MEOTs (0.5560.09 vs. 0.960.2), while the D and ADC values were significantly higher in BEOTs than in MEOTs (2.2760.35 vs. 1.3960.37 and 1.7260.36 vs. 1.160.25, respectively) (P < 0.001). For differentiating between BEOTs and MEOTs, the sensitivity, specificity, and accuracy were 88.2%, 94.3%, and 92.3% for K value; 88.2%, 91.4%, and 90.4% for D value; and 88.2%, 88.6%, and 88.5% for ADC value, respectively. However, there were no differences in the diagnostic performances among the three parameters above (K vs. ADC, P50.203; D vs. ADC, P50.148; K vs. D, P50.904). The K value was positively correlated with Ki-67 expression (r50.699), while the D and ADC values were negatively correlated with Ki-67 expression (r5-0.680, -0.665, respectively). Conclusion: Preliminary findings demonstrate that DKI is an alternative tool for differentiating BEOTs from MEOTs, and is correlated with Ki-67 expression. However, no added value is found for DKI compared with standard DWI. Level of Evidence: 1 Technical Efficacy: Stage 2