Oscillating Gradient Diffusion-Weighted MRI for Risk Stratification of Uterine Endometrial Cancer

Background: Oscillating gradient diffusion-weighted imaging (DWI) enables elucidation of microstructural characteristics in cancers; however, there are limited data to evaluate its utility in patients with endometrial cancer.

Purpose: To investigate the utility of oscillating gradient DWI for risk stratification in patients with uterine endometrial cancer compared with conventional pulsed gradient DWI.

Study type: Retrospective.

Subjects: Sixty-three women (mean age: 58 [range: 32-85] years) with endometrial cancer.

Field strength/sequence: 3 T MRI including DWI using oscillating gradient spin-echo (OGSE) and pulsed gradient spin-echo (PGSE) research sequences.

Assessment: Mean value of the apparent diffusion coefficient (ADC) values for OGSE (ADC_OGSE) and PGSE (ADC_PGSE) as well as the ADC ratio (ADC_OGSE/ADC_PGSE) within endometrial cancer were measured using regions of interest. Prognostic factors (histological grade, deep myometrial invasion, lymphovascular invasion, International Federation of Gynecology and Obstetrics [FIGO] stage, and prognostic risk classification) were tabulated.

Statistical tests: Interobserver agreement was analyzed by calculating the intraclass correlation coefficient. The associations of ADC_OGSE, ADC_PGSE, and ADC_OGSE/ADC_PGSE with prognostic factors were examined using the Kendall rank correlation coefficient, Mann-Whitney U test, and receiver operating characteristic (ROC) curve. A P value of <0.05 was statistically significant.

Results: Compared with ADC_OGSE and ADC_PGSE, ADC_OGSE/ADC_PGSE was significantly and strongly correlated with histological grade (observer 1, τ = 0.563; observer 2, τ = 0.456), FIGO stage (observer 1, τ = 0.354; observer 2, τ = 0.324), and prognostic risk classification (observer 1, τ = 0.456; observer 2, τ = 0.385). The area under the ROC curves of ADC_OGSE/ADC_PGSE for histological grade (observer 1, 0.92, 95% confidence intervals [CIs]: 0.83-0.98; observer 2, 0.84, 95% CI: 0.73-0.92) and prognostic risk (observer 1, 0.80, 95% CI: 0.68-0.89; observer 2, 0.76, 95% CI: 0.63-0.86) were significantly higher than that of ADC_OGSE and ADC_PGSE.

Data conclusion: The ADC ratio obtained via oscillating gradient and pulsed gradient DWIs might be useful imaging biomarkers for risk stratification in patients with endometrial cancer.

Level of evidence: 3 TECHNICAL EFFICACY: Stage 2.