An Analysis of Delta Apparent Diffusion Coefficient Values for Epithelial Ovarian Cancer Classification and Ki-67 Expression

Background: Ovarian cancer is one of the most common malignant tumors of the female reproductive system, characterized by high malignancy and poor prognosis. Epithelial ovarian cancer (EOC) accounts for 90% to 95% of all cases. This study aims to investigate the diagnostic value of delta apparent diffusion coefficient (dADC) values in distinguishing between type I and type II EOC and to explore its correlation with Ki-67 expression. Methods: A retrospective analysis included 95 patients (mean age: 51.6 ± 12.5 y; range: 17 to 73 y) diagnosed with EOC at our hospital from September 2021 to August 2023. Of these, 51 patients had type I EOC (low-grade serous carcinoma, clear cell carcinoma, endometrioid carcinoma, mucinous carcinoma, or borderline tumors), and 44 had type II EOC (high-grade serous carcinoma or high-grade endometrioid carcinoma). Bilateral lesions were observed in 16.8% of patients. Preoperative MRI, including diffusion-weighted imaging (DWI), serum CA125 levels, and postoperative immunohistochemical Ki-67 expression, were analyzed. Tumor staging was based on the 2021 FIGO criteria. Minimum ADC (minADC), maximum ADC (maxADC), and dADC values were calculated from the solid tumor components. Receiver operating characteristic (ROC) curves assessed diagnostic performance, and the correlation between dADC and Ki-67 expression was examined. Results: The maxADC and minADC of type II EOC were lower than those of type I, while dADC was higher than type I ( P <0.05). ROC curve analysis showed that the efficacy of dADC in distinguishing between type I and type II EOC was higher than that of minADC and maxADC ( P <0.05). When the dADC threshold was 0.31×10 −3 mm 2 /s, the area under the curve (AUC) was 0.982, with a sensitivity of 95.3% and specificity of 97.3%. Pearson correlation analysis showed a positive correlation between dADC and Ki-67 expression. Conclusion: dADC has a certain value in accurately distinguishing between type I and type II EOC preoperatively, and it can reflect the proliferative activity of tumor cells.