What is the role of MRI in the diagnosis of adenomyosis?

Updated: Dec 07, 2018
  • Author: Karen L Reuter, MD, FACR; Chief Editor: Eugene C Lin, MD  more...
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Answer

Although it is more expensive than ultrasonography, MRI can be employed in cases with indeterminate sonographic results for adenomyosis or in patients who are undergoing uterine-sparing surgery for leiomyomas. [8, 9]

Thin-section, high-resolution MRI scans obtained with a pelvic multicoil array are optimal for diagnosing adenomyosis. The uterine zonal anatomy is best seen on T2-weighted images.

Variations in the normal thickness of the inner myometrium, or junctional zone, have been reported, with a mean thickness of 2-8 mm. Widening of this junctional zone has been associated with adenomyosis (see the image below). Furthermore, the thickness of a normal junctional zone changes with the menstrual cycle, while the thickness of diffuse adenomyosis does not.

Sagittal magnetic resonance image of an enlarged u Sagittal magnetic resonance image of an enlarged uterus with a thickened posterior myometrium. T2-weighted image without gadolinium enhancement shows a widened junctional zone of 23 mm (arrows) and focal high signal intensity (arrowhead). Same patient as in Images 1 and 2.
Transvaginal sagittal image of the uterus showing Transvaginal sagittal image of the uterus showing indistinct endometrial lining (long yellow arrow) with subcentimeter avascular cyst abutting the posterior endometrial lining (short yellow arrow). Courtesy of Christopher D Scheirey, MD.
Sagittal T2-weighted MRI image (same patient as in Sagittal T2-weighted MRI image (same patient as in previous image) without IV contrast showing a globular hypertrophied uterus (long red arrow) and tiny fluid collection about the endometrial lining, with the short red arrow pointing to the largest one. Courtesy of Christopher D Scheirey, MD.

The most established MRI finding is thickening of the junctional zone exceeding 12 mm. A maximum thickness of 8 mm or less excludes the disease. When the maximum junctional zone diameter is 8-12 mm, secondary findings, such as high–signal-intensity foci on T1- or T2-weighted images, are necessary to make the diagnosis. [3]

The bright foci seen in the myometrium on T2-weighted images in 50% of patients are islands of heterotopic endometrial tissue, cystic dilation of heterotopic glands, or hemorrhage. Whether the hemorrhage is from hormonal changes or from spontaneous causes is not known.

Sometimes, linear striations of decreased signal intensity can be seen radiating out from the endometrium into the myometrium on T2-weighted images. These striations are the direct invasion of the basal endometrium into the myometrium. When the striations blend or become indistinct, pseudo-widening of the endometrium is seen.

Focal adenomyosis, as opposed to diffuse adenomyosis, is seen as a localized, low–signal-intensity mass within the myometrium on both T2-weighted and contrast-enhanced T1-weighted MRIs. In one series of T1-weighted images, most of these masses were isointense relative to the surrounding myometrium. These focal adenomyomas were 2-7 cm in diameter, round or oval, and located in the posterior wall. They also had a poorly defined margin.

The main differential diagnosis of adenomyoma is leiomyoma. Adenomyoma appears as a hypointense mass on T2- weighted images with ill-defined borders, minimal mass effect, and, in some cases, multiple bright foci. Leiomyomas have well-defined borders, despite also being hypointense on T2-weighted images. The presence of large vessels at the periphery may also favor this diagnosis. [3]

The most common lesion of adenomyosis seen on MRI is a low–signal-intensity area on T2-weighted images that often gives the appearance of diffuse or focal widening of the junctional zone. This hypointense area is smooth-muscle hyperplasia accompanying the heterotopic endometrial glands.

Rarely, endometrial carcinoma may arise from adenomyosis. It has been shown that when adenomyosis coexists with endometrial carcinoma at the same site on T2-weighted images, contrast-enhanced T1-weighted images improve the accuracy of staging.

Gadolinium contrast enhancement does not aid in the diagnosis of diffuse adenomyosis.

Gadolinium-based contrast agents have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see Nephrogenic Systemic Fibrosis. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see Medscape.


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