eMedicine Specialties > Radiology > Obstetrics/Gynecology

Uterus, Adenomyosis: Imaging

Author: Karen L Reuter, MD, FACR, Professor, Department of Radiology, Lahey Clinic Medical Center
Contributor Information and Disclosures

Updated: Feb 12, 2009

Magnetic Resonance Imaging

Findings

The second modality commonly used for diagnosing adenomyosis, MRI, although more expensive than ultrasonography, can be employed in cases with indeterminate sonographic results or in patients who are undergoing uterine-sparing surgery for leiomyomas.

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 Image 3). Furthermore, the thickness of a normal junctional zone changes with the menstrual cycle, while the thickness of diffuse adenomyosis does not. However the MRI appearance of adenomyosis can change in response to hormonal stimulation and treatment. Findings from an MRI study of 20 healthy volunteers suggested that the upper limits of a normal junctional zone should be at least 7-8 mm to avoid a high false-positive rate in the diagnosis of adenomyosis. These authors noted that myometrial contractions can appear as adenomyosis.

Haimovici and Tempany reported that a junctional zone of 12 mm or less is normal.² They used findings of focal hyperintensity on T2-weighted images (see Image 3) to confirm the diagnosis of adenomyosis. These authors did not recommend the use of gadolinium enhancement to diagnose adenomyomas in their review article.

In their review of the endovaginal ultrasonographic and MRI features of adenomyosis, Reinhold and colleagues concluded that adenomyosis could be diagnosed with a high degree of accuracy when the junctional zone thickness was 12 mm or greater.^3,4 A maximum thickness of 8 mm or less usually excluded the disease. When the maximum junctional zone diameter was 8-12 mm, secondary findings, such as high–signal-intensity foci on T1- or T2-weighted images, were necessary to make the diagnosis.

The bright foci seen in the myometrium on T2-weighted images in 50% of patients (see Image 3) 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.

In addition to depicting adenomyosis, MRI can be used to distinguish a focal adenomyoma from a leiomyoma. Adenomyomas lack distinct borders and any mass effect on both T2-weighted and contrast-enhanced T1-weighted MRI scans. Furthermore, most focal adenomyomas are in the posterior myometrium. Leiomyomas do not have this predilection. Both adenomyomas and leiomyomas have low signal intensity, although some leiomyomas with hemorrhage have high signal intensity.^5,6,7,8

The most common lesion of adenomyosis seen on magnetic resonance images is a low–signal-intensity area on T2-weighted images that often gives the appearance of diffuse or focal widening of the junctional zone (see Image 3). 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-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. 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 the FDA Public Health Advisory or Medscape.

Degree of Confidence

The reported accuracy of MRI for diagnosing adenomyosis is high. Its sensitivity and specificity are 80-100%, with an overall accuracy of 85-90.5%.

Ultrasonography

Findings

The gross ultrasonographic description of adenomyosis includes irregular, myometrial, cystic spaces predominantly involving the posterior uterine wall, an enlarged uterus with a widened posterior wall (see Image 1), an eccentric endometrial cavity, and decreased uterine echogenicity without lobulations, contour abnormality, or mass effects (which is more commonly seen with leiomyomas). Sonograms may also show an ill-defined margin between the normal myometrium and the abnormal myometrium, as well as an elliptically shaped myometrial abnormality. However, the occurrence of adenomyosis cannot be consistently differentiated from the presence of leiomyomas by using TAUS.^9,10,11

From a series of 29 women with evidence of adenomyosis at hysterectomy, the morphologic criterion for adenomyosis at endovaginal ultrasonography was the presence of myometrial heterogeneous and hypoechoic areas with or without cysts. The sensitivity in that series was 86%, the specificity was 86%, and the positive and negative predictive values were 71% and 94%, respectively.

Endovaginal ultrasonography, especially with a Doppler technique, can be used as the initial imaging modality to determine the presence of adenomyosis. It must be performed meticulously and with real-time imaging. Chiang and colleagues used color Doppler ultrasonography with the morphologic criteria to improve the diagnostic accuracy of ultrasonography in differentiating adenomyosis from leiomyomas.¹² They found that 87% of the cases of adenomyosis had randomly scattered vessels or intratumoral signals. In 88% of leiomyoma cases, they observed peripheral scattered vessels or outer feeding vessels. In addition, in 82% of the adenomyomas, arteries within or around the uterine tumors had a pulsatility index (PI) greater than 1.17, and 84% of leiomyomas had a PI of 1.17 or less.

On sonograms, the most common appearance of adenomyosis is areas of decreased echogenicity or heterogeneity in the myometrium. Specific details of this observation have been analyzed. The areas of decreased echogenicity are those where smooth-muscle hyperplasia has occurred. The areas of heterogeneity are small, echogenic islands of heterotopic endometrial tissues surrounded by hypoechoic smooth muscle. Dilated cystic glands or hemorrhagic foci within the heterotopic endometrial tissue cause the appearance of small myometrial cysts that are smaller than 5 mm in diameter. These are seen in about 50% of patients.

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