♦ ULTRASOUND (US):
COMPLETE MOLE (fig 1,
2a) appears as:
- a heterogeneous echogenic endometrial mass with multiple variable size small anechoic cysts “snowstorm or granular appearance” (because of hydropic villi);
- without fetal tissue;
- increased vascularity with low-resistance waveforms in the spiral arteries of the uterus;
- ovarian enlargement with multiloculated theca lutein cysts < 50% (because of the excessive production of β-hCG) [9,
13].
PARTIAL MOLE (fig 1,
2b) appears similar to complete moles even if fetal tissue is present.
Distinction between the two forms can be difficult.
INVASIVE MOLE and CHORIOCARCINOMA (fig.
3,
4) are largely indistinguishable at ultrasound:
- heterogeneous,
echogenic masses
- hypervascular masses at Doppler US (occasionally helpful in detection of myometrial invasion)
PLACENTAL SITE TROPHOBLASTIC DISEASE manifests as:
- masses with both solid and cystic lesion
- myometrial invasion
♦ MAGNETIC RESONANCE (MR):
Although rarely used,
MR allows to evaluate loco-regional extension of molar tissue demonstrating myometrial and parametrial invasion (fig.
5).
Mole appears as a tissue with low signal on T1 images,
high signal on T2 images,
and avid enhancement on post-contrast images (fig.
6,
7,
8).
When US shows an endometrial or myometrial mass with multiple cystic spaces,
MR imaging is recommended especially to clarify tumor vascularity and the extent of the tumor.
MR imaging may provide useful information in determining the strategy for surgical approach.
On T1- and T2-weighted MR images,
the lesion is usually isointense and slightly hyperintense,
respectively,
relative to the normal myometrium.
On contrast-enhanced T1-weighted images,
the lesion is identified as a strongly enhanced mass with an unenhanced central area (fig.
6,
7,
8) [9,
13].
♦ COMPUTED TOMOGRAPHY (CT):
CT scan is particularly useful [9,
13].:
- to confirm disease (heterogeneous predominantly hypoattenuating intrauterine tissue) and its progression (fig.
9-10) (fig.
11-16);
- in staging neoplasia (invasive mole and choriocarcinoma) by allowing detection of distant metastases (fig.18);
- to identify,
as collateral findings,
imaging features due to excessive production of β-hCG by abnormal trophoblast (fig.17).