A 62-year-old woman undergoes hysteroscopy with endometrial biopsy, which confirms endometrial adenocarcinoma. Before staging and treatment planning, which investigation is most appropriate to assess myometrial invasion and cervical involvement?

Explanation

## Investigation of Choice for Staging Endometrial Carcinoma **Key Point:** MRI pelvis with gadolinium contrast is the imaging modality of choice for preoperative staging of endometrial carcinoma. It provides superior soft tissue contrast resolution for assessing myometrial invasion depth and cervical involvement. ### Why MRI is Superior for Staging **High-Yield:** MRI advantages for endometrial cancer staging: - Excellent soft tissue contrast without ionizing radiation - Accurate assessment of myometrial invasion (critical for grade/stage determination) - Detection of cervical stromal invasion - Identification of adnexal involvement - Sensitivity 80–90% for deep myometrial invasion - Can assess lymph node involvement (size criteria) - Gadolinium enhancement improves visualization of tumor-myometrium interface ### Clinical Pearl: Myometrial invasion depth is a critical prognostic factor in endometrial cancer: - **Superficial invasion** (<50% myometrial thickness) → lower risk of lymph node metastasis - **Deep invasion** (≥50% myometrial thickness) → higher risk, may warrant lymphadenectomy MRI can reliably differentiate these, guiding surgical planning. ### Comparison of Staging Modalities | Investigation | Myometrial Invasion | Cervical Involvement | Lymph Nodes | Radiation | Cost | |---|---|---|---|---|---| | MRI with gadolinium | Excellent (80–90%) | Excellent | Fair (size only) | None | High | | CT abdomen/pelvis | Fair–Good (60–75%) | Fair | Fair (size only) | Yes | Moderate | | Transvaginal ultrasound | Good (70–80%) | Fair | Poor | None | Low | | PET-CT | Poor–Fair | Poor | Good (metabolic) | Yes | Very high | **Mnemonic:** **MRI for STAGE** = **M**yometrial invasion, **R**isk stratification, **I**nvasion depth assessment for **S**urgical **T**actics, **A**dnexal involvement, **G**ynecologic staging, **E**xcellent soft tissue contrast. ### Indications for Preoperative MRI 1. **All endometrial adenocarcinomas** (standard of care in most centers) 2. Grade 2–3 tumors (higher risk of deep invasion) 3. Non-endometrioid histology (serous, clear cell — higher risk) 4. Clinical suspicion of cervical involvement 5. Assessment before fertility-sparing surgery in young women ### Sequence Protocol - **T2-weighted images:** Best for anatomic detail and myometrial zoning - **Diffusion-weighted imaging (DWI):** Helps identify tumor (restricted diffusion) - **Dynamic contrast-enhanced (DCE):** Gadolinium enhancement pattern differentiates tumor from normal myometrium - **T1-weighted post-contrast:** Assesses enhancement kinetics **Clinical Pearl:** The **junctional zone** (innermost myometrium) shows normal enhancement; tumor typically enhances differently, allowing visualization of invasion depth.