E2676. Staging and Follow-Up of Endometrial Cancer: Role of MRI with Attention to Updated Guidelines, Pitfalls and Mimickers
  1. Hannah Fleming; University Health Network
  2. Andrew Nanapragasam; University Health Network
  3. Ciara O'Brien; University Health Network
Endometrial cancer (EC) is the most common female genital tract malignancy in Western countries. Prognosis is based on tumour type, grade and Myometrial Invasion depth (MI), according to the FIGO staging. Benefit of lymphadenectomy in early-stage EC is controversial.The updated European Society of Medical Oncology (ESMO) recommendations defining it only necessary for Stage I, Grade 1 or 2 Endometrial Carcinoma with less than 50% MI. Purpose to assess the role of MRI at revealing MI depth, which correlates with tumour grade, lymph node (LN) metastases and thus prognosis, review the role of MRI in assessment of LN involvement, outline the ability of MRI to confirm disease confined to the endometrium which is required for fertility sparing therapy, review of mimics that can simulate EC, discuss the role of DCE and DWI in improving staging accuracy.

Educational Goals / Teaching Points
MI, diagnosed with MRI, is an important prognostic indicator. MRI can diagnose disease confined to the endometrium which is of paramount importance for fertility sparing treatment. MRI interpretation errors causes diagnostic and staging mistakes during all phases of EC evaluation. Awareness of mimics that can simulate EC is critical. The use of different imaging planes, DWI and DCE to improve accuracy of EC staging is of paramount importance.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
MR Staging of EC (tips on what to avoid and imaging pitfalls). Myometrial invasion [MI] (axial obliques are the most accurate, MRI can overestimate MI if there is a large tumour, isointense to endometrium, if the cornua are involved, or distorted uterine anatomy, TIP: Use DCE and DWI for MI assessment).Cervical stromal iInvasion (sagittal and axial obliques are the most accurate, the cervical stroma must be distorted, TIP: Use delayed DCE). Serosal invasion (TIP: Use DCE and DWI). Parametrial invasion (TIP: Use DWI). Pelvic and para-aortic Lymph node evaluation (TIP: Use T2 and morphology). Value of DCE (more specific than T2 for deep MI especially the equilibrium phase, can confirm uninterrupted enhancement of the sub-endometrial zone which is most accurate on the delayed phase). Value of DWI (good for MI in concurrent adenomyosis, use two b values with an optimal high b value of 800 to 1000 s/mm2, axial oblique plane is the most accurate, together T2 and DWI are superior to DWI or DCE alone). MR evaluation of LN metastases (grade 3 EC and non-endometrioid histology’s are a high risk for LN metastases, DWI through the entire abdomen and pelvis recommended). Future directions (FOCUS DWI predicts tumour grade and extent in uterus-confined disease, -18F-FDG PET/CT superior to MRI for N and M staging, PET/MR, radiomics, radiogenomics).

Accurate MRI assessment and interpretation in EC is crucial for guiding future management in terms of assessing MI and identifying patients with disease confined to the endometrium. MRI interpretation errors causes diagnostic and staging mistakes during all phases of EC evaluation. Awareness of mimics that can simulate EC is critical. Knowledge of the best sequences to use in the assessment of EC is of paramount clinical importance.