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• Uterine endometriosis
• Endometriosis interna

• Heterotopic endometrial tissue within myometrium with adjacent smooth muscle hyperplasia

Best diagnostic clue
·         Uterine enlargement with poor definition of endometrial-myometrial interface
·         Myometrial cysts in up to 50% , Usually subendometrial

·         Diffuse or asymmetric myometrial involvement
      Superficial type: Involving < 1/3 of myometrial thickness
      Deep type: Invasion > 1/3 of myometrial thickness
      When asymmetric, posterior > anterior myometrium
      May be more focal and mass-like, resulting in adenomyoma , Often near endomyometrial junction

If confluent/diffuse, globular enlarged uterus with smooth external contour
If focal, commonly elliptical myometrial mass

Ultrasonographic Findings
1.      Size : Globular uterine enlargement

Sagittal TAS demonstrates globular shape of the uterus

Sagittal TVS shows diffuse myometrial heterogeneity. In addition, the endometrium is poorly defined. 

Transabdominal US shows uterine enlargement and diffuse heterogeneity of the uterine parenchyma with nonvisualization of the endometrium.

2.         Echo texture : Heterogeneous myometrial echotexture - Hypoechoic smooth muscle hyperplasia -  Echogenic linear striations due to endometrial extension into myometrium
Longitudinal transvaginal US demonstrates asymmetric posterior greater than anterior linear bands of echogenicity and shadowing  without a focal mass, consistent with adenomyosis.

3.         Endomyometrial interface : Loss due to thickening of junctional zone

Longitudinal transvaginal US demonstrates asymmetric posterior myometrial thickening with subtle shadowing without a defined mass. The endomyometrial border is partially obscured .

4.  Subendometrial echogenic linear striations

Transverse transabdominal US demonstrates poor delineation of the endomyometrial border , and diffuse myometrial thickening with areas of bandlike shadowing .
5.         Subendometrial echogenic nodules

Transverse TVS shows echogenic nodules. The central echogenic area in this image is the endometrium. Striations and nodules are likely the same feature, with the term “striations” being used when more elongated in shape and “nodules” when more spherical. 

Longitudinal transvaginal US demonstrates subtle invaginations of the endometrium into the myometrium , diagnostic of adenomyosis. Presence of a subendometrial cyst is also highly specific
6.         Cysts within myometrium :  Anechoic, usually subendometrial  , Highly specific for diagnosis . Distinguished from uterine veins, which are peripheral, have color flow Disordered or uncircumscribed myometrial vascular pattern on color Doppler

Sagittal TVS reveals multiple small cysts in the myometrium

7. Tender with probe pressure
8.  If mass-like, difficult to differentiate from leiomyoma but less distinct - Often emanates from endomyometrial junction -  Penetrating vessels without mass effect on color Doppler - Not calcified
NB. Focal adenomyosis is usually the form most difficult to distinguish from leiomyomas. Distinct borders are typical of leiomyomas, whereas indistinct borders suggest adenomyosis. It has been suggested that color or power Doppler may be helpful in making the distinction, with adenomyosis tending to have more central vascularity and leiomyomas tending to have mostly peripheral vascularity. However, the reliability of Doppler findings to make this distinction has not been adequately evaluated. In patients in whom one is uncertain whether the findings represent Adenomyosis Or leiomyomas Or both (when making This distinction Is important For clinical care), MRI is helpful. Although adenomyosis is usually considered to occur mostly in premenopausal women, it can be seen in postmenopausal women.

9.   focal adenomyosis :  when involving only part of the myometrium
Sagittal TAS shows  asymmetrical myometrial thickness, with the posterior myometrium thicker and heterogeneous compared with the anterior myometrium..

Longitudinal transvaginal US demonstrates asymmetric posterior enlargement of the uterus body/fundus without a defined mass

Transverse transvaginal US shows diffuse heterogeneity and thickening of the myometrium without a focal mass. The endomyometrial border is obscured
10.  adenomyoma :  when more distinct  as focal
11.  juvenile cystic adenomyoma  : rarely form , can appear as an isolated cystic mass, larger than the small myometrial cysts typically seen in  Adenomyosis .
12.         9% of affected patients have normal ultrasound findings.

MR Findings
      Thickened junctional zone (> 12 mm) on T2WI, diffuse or focal
      Focal areas of T2 increased signal due to dilated endometrial glands
      May have focal areas of T1 increased signal due to hemorrhage
      If mass-like, difficult to differentiate from leiomyoma :  Often near junctional zone - T2 hypointense due to smooth muscle hyperplasia -  Similar enhancement patterns as leiomyoma

Axial T2WI MR in the same patient demonstrates diffuse but asymmetric thickening of the fundal junctional zone  with subendometrial cysts , diagnostic of adenomyosis.
Transabdominal US shows diffuse heterogeneity of the uterus with asymmetric anterior myometrial thickening with linear refractive shadows , consistent with adenomyosis.
A well-defined hypoechoic mass with posterior shadowing in the posterior fundus  is consistent with an intramural fibroid.

Axial T2WI MR in the same patient better demonstrates heterogeneity of the anterior uterine myometrium with thickening and cysts  as well as the posterior intramural fibroid .

Fluoroscopic Findings
•Hysterosalpingography (HSG)
Small diverticula extending from endometrial cavity

Saline-Infused Hysterosonography
• Saline and bubbles may fill linear tracks in myometrium, producing "myometrial cracks" SHG may show communication between the lesions of adenomyosis and the endometrial cavity.

Best imaging tool
US best initial study for patients with pelvic symptoms . Transvaginal ultrasound best to evaluate endomyometrial interface

MR for equivocal, difficult, or nondiagnostic cases
– T2WI best to evaluate junctional zone
– Less limited by size of uterus and patient
– More comprehensive evaluation of fibroid burden
– Not limited by shadowing

Protocol advice
Cine clips with slow sweep are helpful for subtle findings such as streaky shadowing and small myometrial cysts
Evaluate for uterine tenderness

Differential Diagnosis
• US: Well-defined mass in submucosal, subserosal, or mural location , it May be difficult to distinguish from adenomyoma
• Often multiple, with lobular external uterine contour
• Can be calcified with peripheral vascularity
• MR: Low T1/T2 signal with nonthickened junctional zone

Diffuse Myometrial Hypertrophy
• Endometrial-myometrial borders maintained
• Junctional zone remains well defined
• Heterogeneous myometrium without other findings

Endometrial Cancer
• Irregularly thickened heterogeneous endometrium
• Possible invasion into myometrium with loss of endomyometrial interface

Metastasis to Uterine Corpus
• Rare, most commonly breast, gastric cancers and lymphoma
• Lymphoma rarely primary : Hypoechoic infiltration, preserves contour with less mass
effect on endomyometrial interface

Endometrial Hyperplasia
• Thickened endometrium, may have cystic appearance
• Typically preserved endomyometrial interface

• Etiology
·         Ectopic endometrial tissue within myometrium
·         the histologic diagnosis of adenomyosis requires the presence of endometrial glands or stroma to be located more than 2.5 or 3 mm away from the outer edge of the endometrium.
·         Reactive hypertrophy and hyperplasia of surrounding smooth muscle
·         Etiology poorly understood, but may involve invagination of endometrium directly into myometrium vs. de novo development from müllerian rests

• Associated abnormalities
Endometriosis : ; 22% to 49%
Leiomyomas : Adenomyosis and leiomyomas often coexist; 15% to 57% of women with leiomyomas are reported to also have Adenomyosis in surgical series. It can sometimes be difficult to distinguish  these two entities, or determine if both are present, by ultrasound
  Tamoxifen : Women with breast cancer who are treated with tamoxifen have a higher incidence of adenomyosis. It may be that the estrogen agonist effects of tamoxifen on endometrial tissue cause adenomyosis or reactivate preexisting  adenomyosis.

Diffusely enlarged uterus, may be tender
Often associated with menorrhagia : Less commonly dysmenorrhea or metrorrhagia
Commonly associated with endometriosis
Controversial association with infertility
Often mistaken for fibroids given similar symptoms and ultrasound findings

• Age
Pre- or perimenopausal

• Epidemiology
Often have coexistent leiomyomas
Most commonly multiparous
Association with cesarean sections
The prevalence Of Adenomyosis Is uncertain; There are Widely varying Estimates from 5% to 70%.

• Medical treatment with oral contraceptives or gonadotropin releasing hormone agonists to control symptoms
• Adenomyosis cannot be resected
• Hysterectomy is definitive treatment
• Uterine artery embolization is effective alternative treatment : Results not as reproducible as for leiomyoma

• Enlarged, tender uterus in patient with menorrhagia
Image Interpretation Pearls
• Loss of endomyometrial interface due to thickening of junctional zone
• Abnormal myometrial echogenicity, most commonly hypoechoic, due to smooth muscle hyperplasia
• Echogenic linear striations due to endometrial extension into myometrium

• If findings are equivocal, obtain MR to evaluate for thickened junctional zone (> 12 mm is diagnostic),  However, diagnosis can be made at lower threshold if T1/T2-bright foci or linear high T2 signal striations are Present

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