Multi-pool Model-based Amide Proton Transfer Imaging for Tumor Characterization and Risk Stratification in Endometrial Carcinoma.

Abstract

Purpose: To evaluate whether multi-pool model (MPM)-based amide proton transfer (APT) imaging parameters can assess histological grade, histological type, lymphovascular space invasion (LVSI), and recurrence risk in endometrial carcinoma (EC), relative to conventional apparent diffusion coefficient (ADC) and magnetization transfer ratio asymmetry (MTRasym).

Methods: Preoperative 3.0T MRI was performed in 27 patients with EC at Kagawa University Hospital. Two-dimensional axial APT imaging was conducted using a single-shot fast-spin echo acquisition at 3T. ADC, MTRasym (3.5 ppm), and MPM-based APT imaging parameters were calculated using ROI analysis. Tumor grade, histological type, and LVSI status were obtained from surgical specimens. Recurrence risk was defined according to the Japan Society of Gynecologic Oncology 2023 guidelines. Between-group differences were tested using independent-samples t-tests, Mann-Whitney U tests, one-way analysis of variance, or Kruskal-Wallis tests as appropriate. Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic performance.

Results: APT_T2 was significantly higher in grade 2 than in grade 1 ECs (P < 0.05) and in type II than in type I ECs (P < 0.05), yielding the highest area under the curve (AUC) values of 0.81 and 0.83 for differentiating tumor grade and histological type, respectively. APT_T1 was significantly higher in LVSI-positive tumors than in LVSI-negative tumors (P < 0.05) and showed good performance for predicting LVSI (AUC = 0.84). APT_T1 was also significantly higher in the intermediate-risk group than in the low-risk group and achieved an AUC of 0.78 for differentiating low-risk from non-low-risk groups. MTRasym was likewise significantly higher in the non-low-risk group (P < 0.05) and showed comparable diagnostic performance. In contrast, ADC metrics showed no significant differences across these comparisons.

Conclusion: These preliminary findings indicate that APT_T2 may be useful for assessing histological grade and type, whereas APT_T1 may provide complementary information for evaluating LVSI and stratifying recurrence risk in EC.