Utility of Diffusion-Weighted Imaging in Association With Pathologic Upgrading in Biopsy-Proven Grade I Endometrial Cancer

Background: Prediction of pathologic upgrading is clinically meaningful to identify the optimal candidate of fertility-preserving hormonal treatment in the young patients with biopsy-proven grade I endometrial cancer. Purpose: To investigate the utility of diffusion-weighted imaging (DWI) in association with pathologic upgrading in endometrial cancer. Study Type: Retrospective. Subjects: Preoperative MRI datasets of 221 patients with grade I endometrial cancer on endometrial biopsy (n = 146), dilatation and curettage (n = 66), or either (n = 9). Field Strength/Sequence: 3.0T, including T-2-weighted imaging, DWI with a b-value of 1000 s/mm(2), and dynamic contrast enhanced imaging. Assessment: The tumor size was determined as the longest diameter of the lesion. The minimum apparent diffusion coefficient (ADC(min)) was calculated using histogram analysis of the entire tumor. Statistical Tests: Mann-Whitney U-test, Pearson's chi-square test, Fisher's exact test, intraclass correlation coefficient (ICC) analysis, receiver operating characteristic (ROC) curve analysis, univariate and multivariate logistic regression analysis. Results: Pathologic upgrading was identified in 42 patients (19.0%). Patients with pathologic upgrading had larger tumors and showed lower ADCmin values than those without pathologic upgrading (both P < 0.001). The area under the ROC curve of ADC(min) and tumor size was 0.812 and 0.758, respectively. On multivariate analysis, tumor ADCmin =0.600 x 10(-3) mm(2)/s (odds ratio [OR], 11.8; P < 0.001) and tumor size on MRI >3 cm (OR, 3.24; P = 0.009) were independently associated with pathologic upgrading. Upgrading occurred in 23 of 31 patients (74.2%) with ADC(min) =0.600 x 10(-3) mm(2)/s and tumor size >3 cm, and in 7 of 114 patients (6.1%) with ADCmin >0.600 x 10(-3) mm(2)/s and tumor size =3 cm. Data Conclusion: Tumor ADC and tumor size on MRI may be useful parameters in association with pathologic upgrading in biopsy-proven grade I endometrial cancer.