OPTIMISED MRI PROTOCOL
WHEN?
It is important to perform the MRI study avoiding the menstrual phase to differentiate the physiologic thickening of the JZ during menstruation from the diagnosis of adenomyosis.
To optimisate the MRI study it is should be performed in the late proliferative- secretory phase of the menstrual cycle.
HOW?
T2WI: It should be performed sagital T2WI image of the pelvis,
it can be included an axial plane slanted perpendicular to the line of the miometrium in order to assess properly the thickness of the JZ ( Fig.4)
T1WI and T1WI with fat suppression: It is useful to assess hemorrhagic component,
which appears with high signal in T1 fat suppression.
It is also useful to rule out associated endometriosis.
CONTRAST: It may show a uniform or patchy contrast enhancement.
Usually we don’t include contrast enhanced imaging.
However when adenomyosis coexist with endometrial carcinoma at same site on T2WI,
contrast enhanced dynamic T1WI improves the accurancy of staging.
DIFFUSION ( DWI): Diffusion weighted imaging with ADC measurement may provide another clue for the diagnosis,
because a relatively high ACD in adenomyotic lesions with high signal intensity on T2WI,
may allow differentiation from malignant lesions,
which have a low ADC due to their hifh cellularity.
MRI APPEARANCE OF ADENOMYOSIS
We can differentiate two forms of adenomyosis: Diffuse and focal.
DIFFUSE ADENOMYOSIS:
It appears as a diffuse thickening of the JZ with low signal intensity on T2 .
The most important finding in MR is JZ > 12mm. (Fig.
5).
There can also appear small foci of high signal in T2 weigthed images that represent small foci of heterotopic endometrial tissue or cystic dilatation of the endometrial glands (Fig.
6) ,
linear striations that suggest endometrium within miometrium (Fig.
7) and small hiperintens focus on T1 and T2 that represent hemorrhagic foci (Fig.
8).
The identification of these hemorrhagic foci adds specificity to the diagnosis of adenomyosis.
however they might not be seen due to its little size.
FOCAL ADENOMYOSIS OR ADENOMYOMA:
It appears as a myometrial low-signal mass on T2WI,
with ill-defined margins,
usually ovoid and with a pseudocapsule.
It doesn’t produce significant mass effect.
This form may be in continuity with the JZ or not (Fig.9).
DIFFERENTIAL DIAGNOSIS AND PITFALLS:
Potential Pitfall are physiologic thickening of the JZ in the proliferative phase and uterine contractions, already mentioned.
Leiomyoma represents the main differential diagnosis of focal adenomyosis.
It is the most common gynecological tumor,
affecting 20-30 % of women of chilbearing age.
Most of patients are asymptomatic, when there are clinical symptoms,
usually is metrorrhagia.
Clinically it represents the main differential diagnosis of adenomyosis. A correct diagnosis is important,
because leiomyomas can be treated conservatively ,
while the treatment of choice for adenomyosis is hysterectomy.
According to their location they can be submucosal ,
intramural ,
or subserosal ( Fig.
10).
The intramural leiomyomas are the most frequent,
and we should consider the differential diagnosis with focal adenomyosis or adenomyoma.
Leiomyomas typically have low signal in T1WI and T2WI,
thus they can have the same signal than adenomyoma.
On T2WI it can appear a thin hyperintens ring (due to dilated lymphatic vessels ,
dilated veins and edema) that may help us distinguish between leiomyoma and adenomyoma.
Leiomyomas have well-defined margins,
whereas the interfase between focal adenomyosis and myometrium is irregular.
In addition,
leiomyomas,
unlike adenomyomas have greater myometrial mass effect or distortion.
Miscellaneous : There are other less common entities that can raise the differential diagnosis adenomyosis.
Uterine Adenomatoid tumor also appears as a low signal mass on T2WI,
and it can be well or poorly marginated.
Uterine metastases,
which are rare but may occur especially in breast and gastrointestinal tumors .
Finally myometrial invasion in endometrial carcinoma can also be confused with myometrial invasion of adenomyosis.
COEXISTING DISEASES:
Between 60-80 % of patients with adenomyosis have additional pelvic disease,
most often leiomyoma ( Fig.11).
Endometriosis is also a common disease in women of childbearing age.
It is defined as the presence of functioning endometrial tissue outside the endometrium.
Unlike adenomyosis,
endometriosis consists of extra-uterine endometrial tissue.
The most common location are the ovaries but it can locally affect the uterine horns and other structures like the gastrointestinal tract or urinary tract and other organs outside the pelvis,
like thorax or soft tissue .
It is considered a distinct clinical entity,
but there is a high association between the both of them (Fig.
12).