Ultrasound examination (ultrasound)
Transvaginal ultrasound (TVUS) is the first-line imaging modality for evaluating patients with postmenopausal bleeding. It is significantly superior to the transabdominal approach in assessing intrauterine pathology.
The primary ultrasound presentation is often a nonspecific thickening of the endometrium, which is visually indistinguishable from a polyp or hyperplasia. The main alarming sign of a malignant process is irregularity of the mucosal surface and disruption of the clear boundary between the endometrium and the myometrium (endometrial/myometrial junction).
Additional sonographic techniques:
- Color Doppler mapping (CDM): allows visualization of the internal vascularity of a polypoid lesion expanding the uterine cavity.
- Sonohysterography: when fluid is introduced into the uterine cavity, cancer is outlined as an asymmetric mucosal thickening or an intracavitary polyp.
The main drawback of ultrasound is that the method is only effective for assessing early-stage I disease (for roughly determining the depth of invasion based on the integrity of the hypoechoic halo around the endometrium).
Magnetic resonance imaging (MRI)
MRI is the gold standard and imaging modality of choice for precise local tumor assessment. MRI significantly outperforms ultrasound and CT in determining the depth of invasion into the myometrium and cervical stroma.
Diffusion-weighted imaging (DWI) is of particular importance. Tumor tissue demonstrates restricted diffusion: high signal on DWI and low signal on ADC maps. This property allows for:
- Accurately measuring the depth of invasion even in the presence of coexisting adenomyosis or myomas.
- Detecting extragenital lesions (peritoneal and adnexal metastases).
- Identifying drop metastases (drop metastases) in the vagina and cervix.
MRI signs of FIGO stages
Although FIGO relies on surgical staging, the MRI appearance correlates well with clinical stages.
Stage I (tumor confined to the uterine corpus):
- Ia: invasion of less than 50% of the myometrial thickness. The junctional zone (junctional zone) may be distorted, but if its low signal is preserved, this indicates minimal invasion.
- Ib: invasion of 50% or more. A tumor with intermediate signal intensity is identified in the outer half of the myometrium.
Stage II (invasion of the cervical stroma): On T2-weighted images, a tumor with high/intermediate signal intensity disrupts the low-intensity signal of the normal fibrous cervical stroma. Important: mere prolapse of tumor masses into the cervical canal without stromal invasion does not constitute stage II.
Stage III (local/regional spread):
- IIIa: invasion of the serosa (disruption of the uterine contour) or adnexa.
- IIIb: involvement of the vagina (loss of the hypointense signal of its wall) or parametria.
- IIIc: involvement of pelvic (IIIc1) or para-aortic (IIIc2) lymph nodes. On MRI, they are enlarged (>1 cm in short axis), have irregular contours, areas of necrosis, and abnormal signal intensity.
Stage IV (invasion of adjacent organs or distant metastases):
- IVa: invasion of the bladder or rectal mucosa. The normal low signal from the organ wall is lost. The presence of bullous edema (bullous oedema) alone is not considered a criterion for stage IVa; mucosal involvement must be confirmed.
- IVb: distant metastases, including inguinal nodes and malignant ascites.
Role of CT and PET/CT
Computed tomography (CT) has limited utility in primary diagnosis due to poor soft-tissue contrast. However, the method is indispensable for confirming stage IVb (detecting peritoneal metastases and evaluating lymph nodes), especially in aggressive forms—clear cell and serous papillary carcinomas, which tend to disseminate peritoneally similar to ovarian cancer.
Positron emission tomography (PET/CT) with FDG is rarely used for primary staging, but plays a leading role in suspected local pelvic recurrence and the detection of occult metastases, fundamentally changing patient management.
Briefly: answers to topical questions
Which pelvic lymph node groups are affected in stage IIIc1 endometrial cancer?
In stage IIIc1 endometrial cancer, the pelvic lymph nodes are affected. The provided materials do not detail the anatomical subdivision of pelvic lymph nodes into subgroups.
What are the phases of dynamic contrast-enhanced MRI used to evaluate endometrial cancer?
To evaluate endometrial cancer using magnetic resonance imaging, dynamic multi-phase 3D MRI with intravenous gadolinium administration (gradient echo T1-weighted images) is used. A detailed list of specific dynamic contrast phases (arterial, venous, etc.) is not presented in the educational text.
Class and exam questions
Can ultrasound reliably distinguish endometrial cancer from hyperplasia?
No, the most frequent ultrasound sign is a nonspecific thickening of the endometrium, which is visually indistinguishable from a polyp or hyperplasia. Hysteroscopy with biopsy is required for a definitive diagnosis.
Is tumor prolapse into the cervical canal a sign of stage II disease?
No. Stage II is diagnosed only when there is true invasion into the fibrous cervical stroma. Simple protrusion of the tumor into the canal lumen does not change the stage as long as the stroma itself remains intact.
Does bladder bullous edema signify transition to stage IVa?
No. The presence of bullous edema only indicates that the tumor is located close (in the muscular or subserosal layer). Stage IVa requires biopsy-proven direct invasion into the mucosal lining of the organ.
What else to study on this topic
- MRI criteria for lymph node malignancy
- Differential ultrasound diagnosis of endometrial hyperplasia
- Specifics of metastasis in serous papillary and clear cell carcinoma
- Technique of sonohysterography in oncogynecology
- Artifacts on pelvic diffusion-weighted imaging (DWI)
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