Preoperative risk stratification for lymph node metastasis using 3D volumetric analysis indicator (3D-VAI) in...

We evaluated whether a diffusion-weighted imaging (DWI)-based three-dimensional volumetric analysis indicator (3D-VAI) calculated using a 3D workstation outperforms the conventional simple volume index (VI) in predicting lymph node metastasis (LN + ) in patients with clinical Stage (cStage) I-II endometrioid endometrial carcinoma, and evaluated a rule-based risk-stratification model combining 3D-VAI with serum CA125 levels.

We retrospectively reviewed data from 189 patients who underwent surgical treatment for endometrial cancer between January 2021 and December 2025. A final cohort of 118 patients with cStage I-II, preoperative biopsy-confirmed Grade 1/2 endometrioid carcinoma was analyzed (71 patients excluded, including 14 with overlapping exclusion criteria). Preoperative 3D-VAI was assessed using semi-automatic segmentation on a 3D workstation (SYNAPSE VINCENT) using DWI datasets. Conventional VI was geometrically calculated from 3D maximum diameters on T2-weighted images. Diagnostic performances were compared using receiver operating characteristic (ROC) curve analysis and DeLong's test. A risk-stratification model complementarily combining 3D-VAI (cutoff: 20.752 cm³) and serum CA125 levels (cutoff: 28.0 U/mL) was evaluated.

Postoperative pathology confirmed LN positivity in 12 patients (10.2%). The area under the curve (AUC) for predicting LN + was significantly higher for 3D-VAI than for conventional VI (0.769 vs. 0.657; p=0.019). In the risk-stratification model, patients were categorized into a low-risk group (n=68, 57.6%; both factors below cutoffs) and a high-risk group (n=50, 42.4%; either or both factors elevated). The actual histopathological LN + rate was significantly lower in the low-risk group than in the high-risk group (1.5% [1/68] vs. 22.0% [11/50]; p<0.001), achieving a high negative predictive value of 98.5% (67/68; 95% CI: 92.1%-100.0%) and sensitivity of 91.7% (11/12; 95% CI: 61.5%-99.8%).

Preoperative 3D-VAI based on non-contrast DWI is a significantly superior predictor of LN + compared with conventional geometric VI. Complementarily combining 3D-VAI and serum CA125 successfully identifies an ultra-low-risk subgroup (metastasis rate, 1.5%), which could safely allow for surgical de-escalation or omission of nodal assessment.