The value of the apparent diffusion coefficient in differentiating type II from type I endometrial carcinoma

Diagnostic type II endometrial carcinoma (EC) is considered more aggressive and has a poorer prognosis than type I EC; differentiation between them is helpful for preoperative clinical decision-making. However, the diagnostic value of the apparent diffusion coefficient (ADC) in differentiating them remains unclear.

To investigate the value of ADC in differentiating type II EC from type I EC.

Ninety-four patients with EC who underwent diffusion-weighted imaging (DWI) were retrospectively included and divided into type I and type II subgroups, based on the postoperative pathologic results. We analyzed the clinical characteristics, conventional magnetic resonance imaging manifestations, and ADC mean values (ADC_mean), ADC minimum values (ADC_min), and ADC max values (ADC_max). Receiver operating characteristic (ROC) curve analysis was further used to assess the predictive performance.

The ADC_mean, ADC_min, and tumor size differed significantly between the two subtypes. The area under the ROC curve (AUC) for ADC_mean and ADC_min was 0.787 (95% confidence interval [CI] = 0.692-0.88) and 0.835 (95% CI = 0.751-0.919) for predicting type II EC, respectively. The optimal cut-off value of ADC_mean for prediction was 0.757 × 10^-3 mm²/s with a sensitivity of 91%, a specificity of 58%, and an accuracy of 74%, while for ADC_min was 0.637 × 10^-3 mm²/s with a sensitivity of 82%, a specificity of 73%, and an accuracy of 75%.

EC with lower ADC_mean and ADC_min values derived from DWI, and a larger size, are indicative of type II EC.