Table 3 Radiological assessment of myometrial invasion
From: Radiology–pathology correlation of endometrial carcinoma assessment on magnetic resonance imaging
Scenario | Difficulty | Tips |
|---|---|---|
Large tumour volume (Fig. 5) | - Difficulty in identifying the endometrium/myometrium junction - Thinning of the myometrium because of tumoural distension | - Symmetry and smooth interface favour endometrium confined disease (stage IA) - Smooth uninterrupted band of subendometrial enhancement on early DCE excludes myometrial invasion |
- Some tumours exhibit peritumoural enhancement which may be difficult to distinguish from junctional zone enhancement | - Correlate with T2W sequences. Normal junctional zone has low T2W signal compared to normal myometrium | |
Tumour located in the cornua (Fig. 6) | - Thin overlying myometrium at cornua makes it difficult to estimate percentage of invasion | - Compare to the opposite cornua and be aware of the that there is normal thinning of the myometrium at the cornua - Ensure correct angulation on the oblique reformats of the contrast-enhanced T1 3D volume sequence to enable comparison |
Tumour in multi-fibroid uterus (Fig. 7) | - Distortion of both the myometrial–endometrial junction and the depth of the myometrium | - Look at contrast-enhanced sequences and DWI to delineate the tumour from fibroids |
Tumour in uterus with adenomyosis (Fig. 8) | - Difficulty assessing myometrial invasion versus adenomyosis versus tumour colonisation in adenomyosis | - Look at DWI as adenomyosis usually does not show diffusion restriction - Tumour confined to adenomyosis is not considered to be myoinvasive |
Tumour is isointense to myometrium on T2W (Fig. 9) | - Difficulty in delineating tumour margins and identifying extent of myometrial or serosal invasion | - Post-contrast sequences are best for delineating tumour depth and avoids overestimation |
Tumour with mucinous cystic components (Fig. 10) | Tumours may have mucinous differentiation and develop mucin pools that appear cystic on MRI. These mucin pools when present should be included in the depth evaluation | - Awareness of the possible histology of mucinous differentiation in endometrial carcinoma helps radiologists to be prepared for the variation in the appearance of the tumour |