Validation of MRI short axis analysis for predicting lymphovascular invasion in endometrial cancer patients

In the context of FIGO classification updates in Endometrial Cancer (EC), lymphovascular space invasion (LVSI) is often either missing or wrongly assessed in preoperative histological analysis.

This retrospective study aimed to validate the diagnostic efficacy of systematic short-axis measurement on preoperative MRI for predicting lymphovascular space invasion (LVSI) in patients with EC.

A total of 116 patients who underwent preoperative pelvic MRI between January 2015 and December 2019 were included. Two expert radiologists specializing in female pelvic MRI measured the tumor's short axis (previously described by Lavaud et al) on all sequences in sagittal axes T2-weighted and post-contrast T1-weighted images fat suppressed. MRI findings were compared with preoperative biopsy results and postoperative histopathology.

The analysis revealed the highest discrepancies between preoperative histology combined with MRI images and final pathology in tumor grade (21.6 %), FIGO stage (39.6 %), and myometrial invasion (27.6 %). A 24 mm threshold for the anteroposterior measurement was used as a predictor of LVSI. The model utilizing this cutoff demonstrated good performance (AUC = 0.61, p < 0.001) and correctly reclassified 19.8 % of patients with preoperative FIGO stage I tumors as FIGO stage II or more after surgery.

This approach may enhance the preoperative prediction of LVSI and improve the application of the updated FIGO classification in endometrial cancer. The results suggest that MRI-derived short-axis measurement could be a valuable tool for refining the preoperative assessment of LVSI in EC patients.