What are the MRI characteristics of a uterine adenomyoma?

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Last updated: September 15, 2026 • View editorial policy

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Uterine Adenomyoma on MRI

A uterine adenomyoma appears on MRI as a well-circumscribed mass that is typically isointense to the myometrium on T1-weighted images, shows variable signal intensity on T2-weighted images, and characteristically contains hemorrhagic cavities appearing as high signal intensity foci on T1-weighted images, often with concomitant adenomyosis elsewhere in the uterus 1.

Key MRI Characteristics

Location and Morphology

  • Most commonly submucosal (protruding into the endometrial cavity), but can also be subserosal or intramural 1, 2
  • Well-circumscribed margins on both T2-weighted and contrast-enhanced fat-suppressed T1-weighted images 1
  • Can present as polypoid masses with a stalk, though the stalk may become less identifiable as the tumor grows 3

Signal Intensity Patterns

T1-Weighted Images:

  • Solid portions show isointensity compared to normal myometrium 1
  • High signal intensity hemorrhagic cavities are present in approximately 85% of cases (6 of 7 cases in the primary study), reflecting hemorrhagic areas within ectopic endometrial tissue 1

T2-Weighted Images:

  • Variable signal intensity in the solid portions 1, 2
  • Contains cystic structures representing functional endometrium and dilated endometrial glands 2
  • Some septal areas may show strong hypointense signal similar to the junctional zone 3, 4

Enhancement Pattern

  • Intense homogeneous enhancement similar to normal myometrium on contrast-enhanced images 1, 2
  • Satisfactory contrast enhancement of septa within cystic areas 3

Associated Findings

Concomitant adenomyosis is observed in approximately 70% of cases (5 of 7 cases), making this an important diagnostic clue 1. When present, the background myometrium shows typical adenomyosis features including junctional zone thickening or ill-defined areas of low signal intensity on T2-weighted images 5.

Advanced Imaging Features

Diffusion-Weighted Imaging (DWI):

  • Adenomyomas typically do not show high signal intensity compared to normal myometrium on DWI, helping differentiate them from malignant lesions 2

Susceptibility-Weighted Imaging (SWI):

  • Reveals punctate low intensity areas reflecting blood contents, further confirming the hemorrhagic nature of the lesion 2

Critical Diagnostic Pitfalls

The most important caveat is that adenomyoma of endocervical type can mimic minimal deviation adenocarcinoma on small biopsy specimens 3. In these cases, MRI morphology becomes crucial for preoperative diagnosis. Look for:

  • Previous imaging showing a stalked polypoid mass originating from the endocervical wall
  • Multifocal cystic structures with hypointense fluid on T1WI and hyperintense on T2WI
  • Characteristic septal enhancement patterns

Differential Diagnosis Considerations

When encountering a well-circumscribed uterine mass with hemorrhagic cavities and cysts, consider adenomyoma particularly when:

  • Background adenomyosis is present (strongest predictor)
  • Enhancement pattern matches the myometrium (not typical of leiomyomas)
  • Multiple hemorrhagic foci are visible on T1-weighted images
  • The lesion shows no restricted diffusion (helps exclude malignancy)

The combination of these MRI features—well-defined margins, hemorrhagic cavities, cystic components, myometrium-like enhancement, and associated adenomyosis—creates a highly specific imaging signature for adenomyoma 1, 2, 4.

References

1
Research

MR imaging features of uterine adenomyomas.

Abdominal imaging, 2011

5
Research

Spectrum of MR features in adenomyosis.

Best practice & research. Clinical obstetrics & gynaecology, 2006

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