(Radiographics. 1999;19:S147-S160.)
© RSNA, 1999
Uterine Adenomyosis: Endovaginal US and MR Imaging Features with Histopathologic Correlation1
Caroline Reinhold, MD ,
Faranak Tafazoli, MD ,
Amira Mehio, MD ,
Lin Wang, MD ,
Mostafa Atri, MD ,
Evan S. Siegelman, MD and
Lori Rohoman, ACR, RTMR
1 From the Departments of Radiology (C.R., F.T., L.W., L.R.) and Pathology (A.M.), Montreal General Hospital and McGill University, 1650 Cedar Ave, Montreal, Quebec, Canada H3G 1A4; the Department of Radiology, Princess Margaret Hospital, Toronto, Ontario, Canada (M.A.); and the Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia (E.S.S.). Recipient of a Certificate of Merit award for a scientific exhibit at the 1998 RSNA scientific assembly. Received March 4, 1999; revision requested April 16 and received July 7; accepted July 7. Address reprint requests to C.R.
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Abstract
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Uterine adenomyosis is a common gynecologic condition that is characterized by the presence of heterotopic endometrial glands and stroma in the myometrium with adjacent smooth muscle hyperplasia. The histopathologic features of adenomyosis are varied and contribute to its imaging appearance. The accompanying smooth muscle hyperplasia produces the typical gross appearance of adenomyosis and corresponds to areas of decreased echogenicity at endovaginal ultrasonography (US) and areas of decreased signal intensity at magnetic resonance (MR) imaging. Endovaginal US also shows heterogeneity of the myometrial echotexture, which corresponds to small echogenic islands of heterotopic endometrial tissue surrounded by the hypoechoic smooth muscle. On T2-weighted MR images, bright foci are seen in areas of abnormal low signal intensity within the myometrium in approximately 50% of patients. These foci correspond to islands of heterotopic endometrial tissue, cystic dilatation of heterotopic glands, or hemorrhagic foci. With the advent of high-resolution imaging techniques, signs associated with the presence of heterotopic endometrial tissue are being detected with increasing frequency. These signs include myometrial cysts, myometrial nodules, linear striations, pseudowidening of the endometrium, and poor definition of the endomyometrial junction. Pitfalls in diagnosis of uterine adenomyosis include leiomyoma, endometrial carcinoma, myometrial contractions, and muscular hypertrophy.
Index Terms: Endometriosis, 854.3192 • Uterus, diseases, 854.3192 • Uterus, MR, 854.1214 • Uterus, US, 854.12989
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INTRODUCTION
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Uterine adenomyosis is a common gynecologic condition that is characterized at histopathologic analysis by the presence of heterotopic endometrial glands and stroma in the myometrium with adjacent smooth muscle hyperplasia. The typical symptoms include pelvic pain, dysmenorrhea, and menorrhagia. However, these symptoms are nonspecific and can be encountered in disorders such as dysfunctional uterine bleeding, leiomyoma, and endometriosis. The role of imaging in evaluating patients with suspected adenomyosis is as follows.
First, the correct diagnosis is established with imaging. Uterus-conserving therapy is possible in cases of leiomyoma, whereas hysterectomy is the definitive treatment for debilitating adenomyosis. Second, imaging is performed to determine the extent and depth of myometrial penetration. Symptoms have been shown to correlate with the extent of disease. Determining the depth of myometrial penetration is important for treatment planning because superficial adenomyosis responds significantly better to endometrial ablation than does deep adenomyosis. Third, imaging is used to monitor the evolution of the disease in patients receiving conservative therapy.
With the advent of high-resolution imaging techniques, adenomyosis can be diagnosed with a high degree of accuracy. The imaging signs demonstrated with endovaginal ultrasonography (US) and magnetic resonance (MR) imaging correspond closely to the varied appearances of this disease at histopathologic analysis. In this article, histopathologic features, endovaginal US, MR imaging, and diagnostic pitfalls of uterine adenomyosis are discussed.
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HISTOPATHOLOGIC FEATURES
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Understanding the gross and histopathologic features associated with adenomyosis is crucial when interpreting the associated imaging findings. The smooth muscle hyperplasia accompanying the heterotopic endometrial tissue actually produces the characteristic gross appearance of this disease. Nevertheless, the heterotopic endometrial tissue also contributes to the imaging appearance of adenomyosis. With the advent of high-resolution imaging techniques, these changes are being detected with increasing frequency.
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ENDOVAGINAL US
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Transducers used for endovaginal US operate at high frequencies, usually on the order of 5–7 MHz. Endovaginal US produces high-resolution images of the uterus, thus facilitating the detection of adenomyosis. The US signs of adenomyosis must be identified during the real-time examination; they cannot be reliably identified on static images.
The normal uterus shows zones with different degrees of echogenicity at endovaginal US (Fig 1). It is the stratum basale of the endometrium that gives rise to the heterotopic endometrial tissue in adenomyosis. However, this layer is very thin and cannot be identified as a separate entity at US. The presence of adenomyosis can alter and distort the US appearance of these uterine zones.
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Figure 1. Normal uterus. Sagittal endovaginal US scan shows a normal myometrium (M), which is moderately echogenic and has a homogeneous echotexture. The subendometrial halo, which represents the innermost layer of the myometrium, is visualized subjacent to the endometrium (E) as a thin hypoechoic band (arrows). The endometrium is uniformly echogenic in this patient, who was in the secretory phase of the menstrual cycle.
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Features of Adenomyosis
Adenomyosis most commonly appears as areas of decreased echogenicity or heterogeneity of the myometrium, a sign found in approximately 75% of patients (1–3). The areas of decreased echogenicity correspond to areas of smooth muscle hyperplasia at histopathologic analysis. The areas of heterogeneity correspond to small echogenic islands of heterotopic endometrial tissue surrounded by the hypoechoic smooth muscle (Fig 2). The ratio of heterotopic endometrial tissue to smooth muscle partly determines the imaging appearance (Fig 3). The presence of dilated cystic glands or hemorrhagic foci within the heterotopic endometrial tissue results in the presence of small myometrial cysts (usually <5 mm in diameter) in approximately 50% of patients (Figs 4, 5). However, in a rare form of adenomyosis called cystic adenomyosis, the extent and degree of hemorrhage within the ectopic endometrial glands are more extensive (4). When large or confluent, the areas of heterotopic endometrial tissue result in discrete echogenic nodules (
5 mm in diameter) within the myometrium (Fig 5). Heterotopic endometrium extending into the inner myometrium can give the appearance of echogenic linear striations (Figs 6, 7). When these striations are small or indistinct, the US appearance is that of pseudowidening of the endometrium or poor definition of the endomyometrial junction (Figs 7, 8). Other endovaginal US signs of adenomyosis include lack of contour abnormality or mass effect (Figs 2, 3, 5), ill-defined margins between normal and abnormal myometrium (Figs 2, 3, 5, 8), and an elliptical shape of a myometrial abnormality (Figs 2, 5). The endovaginal US signs of adenomyosis are summarized in the Table.
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Figure 2a. Imaging signs of adenomyosis. E = endometrium. (a) Sagittal oblique endovaginal US scan shows that the myometrium is thickened ventrally and has a heterogeneous echotexture (straight arrows). The echogenicity of the ventral myometrium is decreased relative to that of the dorsal myometrium. Additional features of adenomyosis seen in this image include poor definition of the endomyometrial junction and a myometrial cyst (curved arrow). (b) Corresponding sagittal T2-weighted MR image shows marked thickening of the junctional zone. The result is a poorly defined low-signal-intensity mass that replaces the ventral myometrium (arrows). The numerous bright foci, some of which have a rounded appearance whereas others have a linear or fingerlike appearance, represent the heterotopic endometrium. Bl = bladder. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the middle aspect of the ventral myometrium shows foci of heterotopic endometrium scattered throughout the inner two-thirds of the myometrium (small arrows). The heterotopic islands have a linear or rounded appearance (see magnified views). The smooth muscle hyperplasia (dark pink stain) surrounds the heterotopic endometrium. Cysts of adenomyosis are noted in the outer myometrium (large arrows). The endometrial tissue extending into the myometrium results in poor definition of the endomyometrial junction at imaging.
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Figure 2b. Imaging signs of adenomyosis. E = endometrium. (a) Sagittal oblique endovaginal US scan shows that the myometrium is thickened ventrally and has a heterogeneous echotexture (straight arrows). The echogenicity of the ventral myometrium is decreased relative to that of the dorsal myometrium. Additional features of adenomyosis seen in this image include poor definition of the endomyometrial junction and a myometrial cyst (curved arrow). (b) Corresponding sagittal T2-weighted MR image shows marked thickening of the junctional zone. The result is a poorly defined low-signal-intensity mass that replaces the ventral myometrium (arrows). The numerous bright foci, some of which have a rounded appearance whereas others have a linear or fingerlike appearance, represent the heterotopic endometrium. Bl = bladder. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the middle aspect of the ventral myometrium shows foci of heterotopic endometrium scattered throughout the inner two-thirds of the myometrium (small arrows). The heterotopic islands have a linear or rounded appearance (see magnified views). The smooth muscle hyperplasia (dark pink stain) surrounds the heterotopic endometrium. Cysts of adenomyosis are noted in the outer myometrium (large arrows). The endometrial tissue extending into the myometrium results in poor definition of the endomyometrial junction at imaging.
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Figure 2c. Imaging signs of adenomyosis. E = endometrium. (a) Sagittal oblique endovaginal US scan shows that the myometrium is thickened ventrally and has a heterogeneous echotexture (straight arrows). The echogenicity of the ventral myometrium is decreased relative to that of the dorsal myometrium. Additional features of adenomyosis seen in this image include poor definition of the endomyometrial junction and a myometrial cyst (curved arrow). (b) Corresponding sagittal T2-weighted MR image shows marked thickening of the junctional zone. The result is a poorly defined low-signal-intensity mass that replaces the ventral myometrium (arrows). The numerous bright foci, some of which have a rounded appearance whereas others have a linear or fingerlike appearance, represent the heterotopic endometrium. Bl = bladder. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the middle aspect of the ventral myometrium shows foci of heterotopic endometrium scattered throughout the inner two-thirds of the myometrium (small arrows). The heterotopic islands have a linear or rounded appearance (see magnified views). The smooth muscle hyperplasia (dark pink stain) surrounds the heterotopic endometrium. Cysts of adenomyosis are noted in the outer myometrium (large arrows). The endometrial tissue extending into the myometrium results in poor definition of the endomyometrial junction at imaging.
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Figure 3a. Variable echogenicity in a patient with diffuse adenomyosis extending into the outer myometrium. (a) Sagittal oblique endovaginal US scan shows that most regions of the myometrium are hypoechoic and heterogeneous. However, an area of increased echogenicity (arrows) is seen in the ventral myometrium adjacent to the fundus and immediately deep to the endometrium (E) dorsally. The borders of the endometrium are obscured at this level due to the increased echogenicity of the adjacent myometrium, thus resulting in pseudowidening of the endometrium. (b) Photomicrograph (hematoxylin-eosin stain) shows that the ratio of heterotopic endometrial tissue (arrows) to smooth muscle hyperplasia (dark pink stain) is greatest in the ventral myometrium (VM), which corresponds to the area of increased echogenicity on the endovaginal US scan (a). E = endometrium.
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Figure 3b. Variable echogenicity in a patient with diffuse adenomyosis extending into the outer myometrium. (a) Sagittal oblique endovaginal US scan shows that most regions of the myometrium are hypoechoic and heterogeneous. However, an area of increased echogenicity (arrows) is seen in the ventral myometrium adjacent to the fundus and immediately deep to the endometrium (E) dorsally. The borders of the endometrium are obscured at this level due to the increased echogenicity of the adjacent myometrium, thus resulting in pseudowidening of the endometrium. (b) Photomicrograph (hematoxylin-eosin stain) shows that the ratio of heterotopic endometrial tissue (arrows) to smooth muscle hyperplasia (dark pink stain) is greatest in the ventral myometrium (VM), which corresponds to the area of increased echogenicity on the endovaginal US scan (a). E = endometrium.
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Figure 4a. Myometrial cyst. E = endometrium. (a) Transverse oblique endovaginal US scan shows a 6-mm-diameter cyst in the left dorsal aspect of the inner myometrium (arrow). (b) Photomicrograph (hematoxylin-eosin stain) of a section through the dorsal myometrium shows the cyst (magnified view).
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Figure 4b. Myometrial cyst. E = endometrium. (a) Transverse oblique endovaginal US scan shows a 6-mm-diameter cyst in the left dorsal aspect of the inner myometrium (arrow). (b) Photomicrograph (hematoxylin-eosin stain) of a section through the dorsal myometrium shows the cyst (magnified view).
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Figure 5a. Hyperechoic nodules. E = endometrium. (a) Sagittal oblique endovaginal US scan of a patient receiving tamoxifen therapy shows that the inner myometrium is hypoechoic and heterogeneous. Several echogenic nodules consistent with large islands of heterotopic endometrium are seen (short arrows). A myometrial cyst is also present (long arrow). (b) Transverse oblique endovaginal US scan of another patient shows a large echogenic nodule with a central cystic area in the inner aspect of the dorsal myometrium (arrows). (c) Photomicrograph (hematoxylin-eosin stain) of a section through the dorsal uterus (same patient as in b) shows a large heterotopic island of endometrial tissue in the inner myometrium (arrows).
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Figure 5b. Hyperechoic nodules. E = endometrium. (a) Sagittal oblique endovaginal US scan of a patient receiving tamoxifen therapy shows that the inner myometrium is hypoechoic and heterogeneous. Several echogenic nodules consistent with large islands of heterotopic endometrium are seen (short arrows). A myometrial cyst is also present (long arrow). (b) Transverse oblique endovaginal US scan of another patient shows a large echogenic nodule with a central cystic area in the inner aspect of the dorsal myometrium (arrows). (c) Photomicrograph (hematoxylin-eosin stain) of a section through the dorsal uterus (same patient as in b) shows a large heterotopic island of endometrial tissue in the inner myometrium (arrows).
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Figure 5c. Hyperechoic nodules. E = endometrium. (a) Sagittal oblique endovaginal US scan of a patient receiving tamoxifen therapy shows that the inner myometrium is hypoechoic and heterogeneous. Several echogenic nodules consistent with large islands of heterotopic endometrium are seen (short arrows). A myometrial cyst is also present (long arrow). (b) Transverse oblique endovaginal US scan of another patient shows a large echogenic nodule with a central cystic area in the inner aspect of the dorsal myometrium (arrows). (c) Photomicrograph (hematoxylin-eosin stain) of a section through the dorsal uterus (same patient as in b) shows a large heterotopic island of endometrial tissue in the inner myometrium (arrows).
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Figures 6, 7. (6) Echogenic linear striations. Transverse oblique endovaginal US scan shows that the myometrium is hypoechoic and slightly heterogeneous, an appearance consistent with diffuse adenomyosis. Echogenic linear striations (arrows) can be seen radiating out from the endometrium (E) dorsally. The linear striations represent the ectopic endometrial tissue that is in direct continuity with the endometrium. (7) Linear striations. (a) Sagittal endovaginal US scan shows that the myometrium is heterogeneous and of decreased echogenicity. There is pseudowidening of the endometrium (E) at the level of the fundus. Echogenic linear striations can be seen radiating out from the endometrium (arrows). (b) Corresponding sagittal T2-weighted MR image shows diffuse widening of the junctional zone. Linear striations of high signal intensity (arrows) can be seen radiating out from the endometrium (E) at the level of the fundus. Si = sigmoid colon.
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Figures 6, 7. (6) Echogenic linear striations. Transverse oblique endovaginal US scan shows that the myometrium is hypoechoic and slightly heterogeneous, an appearance consistent with diffuse adenomyosis. Echogenic linear striations (arrows) can be seen radiating out from the endometrium (E) dorsally. The linear striations represent the ectopic endometrial tissue that is in direct continuity with the endometrium. (7) Linear striations. (a) Sagittal endovaginal US scan shows that the myometrium is heterogeneous and of decreased echogenicity. There is pseudowidening of the endometrium (E) at the level of the fundus. Echogenic linear striations can be seen radiating out from the endometrium (arrows). (b) Corresponding sagittal T2-weighted MR image shows diffuse widening of the junctional zone. Linear striations of high signal intensity (arrows) can be seen radiating out from the endometrium (E) at the level of the fundus. Si = sigmoid colon.
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Figures 6, 7. (6) Echogenic linear striations. Transverse oblique endovaginal US scan shows that the myometrium is hypoechoic and slightly heterogeneous, an appearance consistent with diffuse adenomyosis. Echogenic linear striations (arrows) can be seen radiating out from the endometrium (E) dorsally. The linear striations represent the ectopic endometrial tissue that is in direct continuity with the endometrium. (7) Linear striations. (a) Sagittal endovaginal US scan shows that the myometrium is heterogeneous and of decreased echogenicity. There is pseudowidening of the endometrium (E) at the level of the fundus. Echogenic linear striations can be seen radiating out from the endometrium (arrows). (b) Corresponding sagittal T2-weighted MR image shows diffuse widening of the junctional zone. Linear striations of high signal intensity (arrows) can be seen radiating out from the endometrium (E) at the level of the fundus. Si = sigmoid colon.
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Figure 8a. Poor definition of the endomyometrial junction. E = endometrium. (a) Transverse oblique endovaginal US scan shows that the ventral myometrium (VM) is markedly heterogeneous, with areas of increased and decreased echogenicity. The abnormal myometrial echotexture results in poor definition of the endomyometrial junction ventrally (arrows). Contrast this appearance with the well-defined appearance of the endomyometrial junction dorsally. (b) Corresponding axial T2-weighted MR image shows thickening of the junctional zone that is most marked ventrally (VM), with multiple foci of increased signal intensity. Owing to the differences in signal intensity between the endometrium (E) and the adjacent myometrium, the endomyometrial junction remains relatively well defined. Cx = cervix. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows extensive adenomyosis with numerous foci of heterotopic endometrial tissue throughout the myometrium (arrows). Note the poor definition of the endomyometrial junction. (d) Photomicrograph (hematoxylin-eosin stain) of a section through a normal uterus shows deep crypts of endometrial glands (arrow), which result in an undulating appearance of the endomyometrial junction. However, the endomyometrial junction remains well defined.
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Figure 8b. Poor definition of the endomyometrial junction. E = endometrium. (a) Transverse oblique endovaginal US scan shows that the ventral myometrium (VM) is markedly heterogeneous, with areas of increased and decreased echogenicity. The abnormal myometrial echotexture results in poor definition of the endomyometrial junction ventrally (arrows). Contrast this appearance with the well-defined appearance of the endomyometrial junction dorsally. (b) Corresponding axial T2-weighted MR image shows thickening of the junctional zone that is most marked ventrally (VM), with multiple foci of increased signal intensity. Owing to the differences in signal intensity between the endometrium (E) and the adjacent myometrium, the endomyometrial junction remains relatively well defined. Cx = cervix. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows extensive adenomyosis with numerous foci of heterotopic endometrial tissue throughout the myometrium (arrows). Note the poor definition of the endomyometrial junction. (d) Photomicrograph (hematoxylin-eosin stain) of a section through a normal uterus shows deep crypts of endometrial glands (arrow), which result in an undulating appearance of the endomyometrial junction. However, the endomyometrial junction remains well defined.
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Figure 8c. Poor definition of the endomyometrial junction. E = endometrium. (a) Transverse oblique endovaginal US scan shows that the ventral myometrium (VM) is markedly heterogeneous, with areas of increased and decreased echogenicity. The abnormal myometrial echotexture results in poor definition of the endomyometrial junction ventrally (arrows). Contrast this appearance with the well-defined appearance of the endomyometrial junction dorsally. (b) Corresponding axial T2-weighted MR image shows thickening of the junctional zone that is most marked ventrally (VM), with multiple foci of increased signal intensity. Owing to the differences in signal intensity between the endometrium (E) and the adjacent myometrium, the endomyometrial junction remains relatively well defined. Cx = cervix. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows extensive adenomyosis with numerous foci of heterotopic endometrial tissue throughout the myometrium (arrows). Note the poor definition of the endomyometrial junction. (d) Photomicrograph (hematoxylin-eosin stain) of a section through a normal uterus shows deep crypts of endometrial glands (arrow), which result in an undulating appearance of the endomyometrial junction. However, the endomyometrial junction remains well defined.
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Figure 8d. Poor definition of the endomyometrial junction. E = endometrium. (a) Transverse oblique endovaginal US scan shows that the ventral myometrium (VM) is markedly heterogeneous, with areas of increased and decreased echogenicity. The abnormal myometrial echotexture results in poor definition of the endomyometrial junction ventrally (arrows). Contrast this appearance with the well-defined appearance of the endomyometrial junction dorsally. (b) Corresponding axial T2-weighted MR image shows thickening of the junctional zone that is most marked ventrally (VM), with multiple foci of increased signal intensity. Owing to the differences in signal intensity between the endometrium (E) and the adjacent myometrium, the endomyometrial junction remains relatively well defined. Cx = cervix. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows extensive adenomyosis with numerous foci of heterotopic endometrial tissue throughout the myometrium (arrows). Note the poor definition of the endomyometrial junction. (d) Photomicrograph (hematoxylin-eosin stain) of a section through a normal uterus shows deep crypts of endometrial glands (arrow), which result in an undulating appearance of the endomyometrial junction. However, the endomyometrial junction remains well defined.
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Accuracy of Diagnosis
When the previously described endovaginal US criteria for diagnosing adenomyosis are used, the sensitivity of endovaginal US has been reported to be 80%–86%, the specificity 50%–96%, and the overall accuracy 68%–86% (1–3).
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MR IMAGING
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Thin-section high-resolution MR images acquired with a pelvic multicoil array are optimal for diagnosis of adenomyosis. At MR imaging, the uterine zonal anatomy is best demonstrated with sagittal T2-weighted sequences. In women of reproductive age, three zones can be identified within the uterine corpus on T2-weighted images (Fig 9).
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Figure 9. Normal uterus. Sagittal T2-weighted MR image shows a centrally located high-signal-intensity stripe, which represents the endometrium (E). Immediately subjacent is a band of low signal intensity, which is located within the inner myometrium and represents the junctional zone (JZ). The outer myometrium is of intermediate signal intensity. Bl = bladder.
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Considerable variation in the normal thickness of the inner myometrium or junctional zone has been reported, with a mean thickness of 2–8 mm. Abnormal widening of the junctional zone is one of the MR imaging features associated with adenomyosis.
Features of Adenomyosis
The predominant lesion of adenomyosis at MR imaging consists of a low-signal-intensity area on T2-weighted images, which frequently gives the appearance of diffuse or focal widening of the junctional zone (5) (Figs 7b, 8b, 10). These areas of low signal intensity have been shown to correspond to the smooth muscle hyperplasia accompanying the heterotopic endometrial tissue. In a prospective study of 119 patients, 28 of whom had histopathologically diagnosed adenomyosis, a significant difference in mean junctional zone thickness at MR imaging was found between patients with and patients without the disease (5). When the maximal junctional zone thickness was 12 mm or greater, adenomyosis was diagnosed with a high degree of accuracy; conversely, a maximal junctional zone thickness of 8 mm or less usually allowed exclusion of the disease. In patients with a maximal junctional zone thickness of 8–12 mm, secondary findings such as relative thickening of the junctional zone in a localized area, poor definition of borders, or high-signal-intensity foci on T2- or T1-weighted images can be used to diagnose adenomyosis.
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Figure 10. Focal thickening of the junctional zone. Sagittal T2-weighted MR image shows focal thickening of the junctional zone at the level of the fundus (arrows). Although the maximal thickness of the junctional zone was more than 12 mm in this patient, any focal thickening of the junctional zone should raise the possibility of adenomyosis. Bl = bladder, E = endometrium.
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On T2-weighted images, bright foci are seen in areas of abnormal low signal intensity within the myometrium in approximately 50% of patients (5). These foci correspond to islands of heterotopic endometrial tissue, cystic dilatation of heterotopic glands, or hemorrhagic foci (Figs 2b, 11a). In addition to bright foci, linear striations of increased signal intensity can be seen radiating out from the endometrium into the myometrium on T2-weighted images. These striations represent direct invasion of the basal endometrium into the myometrium (Figs 2b, 7b). When these striations blend or become indistinct, the resulting appearance is that of pseudowidening of the endometrium (Fig 12). Bright foci on T1-weighted images are seen much less frequently and correspond to areas of hemorrhage (6) (Fig 11b). The exact mechanism of the hemorrhage is unclear because adenomyosis involves only the basal layer of the endometrium, not the functional layer. Nevertheless, hormonal receptors exhibiting some degree of proliferative and secretory changes during the menstrual cycle have been identified in adenomyotic implants (7,8). However, whether the hemorrhage within implants of adenomyosis represents a sequela of hormonal changes during the menstrual cycle or is the result of spontaneous hemorrhage has not yet been elucidated. When the degree of hemorrhage is extensive, cystic adenomyosis can result. Cystic adenomyosis is characterized by a well-circumscribed, cystic myometrial lesion that demonstrates hemorrhage in differential stages of organization at MR imaging (9) (Figs 13, 14). On T2-weighted images, cystic adenomyosis typically demonstrates a low-signal-intensity rim (Fig 13a).
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Figure 11a. High-signal-intensity foci. C = left ovarian cyst, Cx = cervix, E = endometrium. (a) Axial T2-weighted MR image shows an ill-defined low-signal-intensity mass with numerous foci of increased signal intensity that replaces the left side of the myometrium (arrows). (b) Axial T1-weighted MR image shows several foci of increased signal intensity (arrowheads), which correspond to areas of hemorrhage within the adenomyotic tissue. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the uterus shows numerous foci of heterotopic endometrial tissue throughout the myometrium (arrowheads). Note also the smooth muscle hyperplasia (dark pink stain) surrounding the heterotopic tissue.
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Figure 11b. High-signal-intensity foci. C = left ovarian cyst, Cx = cervix, E = endometrium. (a) Axial T2-weighted MR image shows an ill-defined low-signal-intensity mass with numerous foci of increased signal intensity that replaces the left side of the myometrium (arrows). (b) Axial T1-weighted MR image shows several foci of increased signal intensity (arrowheads), which correspond to areas of hemorrhage within the adenomyotic tissue. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the uterus shows numerous foci of heterotopic endometrial tissue throughout the myometrium (arrowheads). Note also the smooth muscle hyperplasia (dark pink stain) surrounding the heterotopic tissue.
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Figure 11c. High-signal-intensity foci. C = left ovarian cyst, Cx = cervix, E = endometrium. (a) Axial T2-weighted MR image shows an ill-defined low-signal-intensity mass with numerous foci of increased signal intensity that replaces the left side of the myometrium (arrows). (b) Axial T1-weighted MR image shows several foci of increased signal intensity (arrowheads), which correspond to areas of hemorrhage within the adenomyotic tissue. (c) Photomicrograph (hematoxylin-eosin stain) of a section through the uterus shows numerous foci of heterotopic endometrial tissue throughout the myometrium (arrowheads). Note also the smooth muscle hyperplasia (dark pink stain) surrounding the heterotopic tissue.
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Figure 12a. Pseudowidening of the endometrium. Sagittal (a) and axial (b) T2-weighted MR images show diffuse thickening of the junctional zone, aside from a central area of the dorsal myometrium. Note the blending of the fine linear hyperintense striations that extend out into the ventral myometrium (arrows); this blending results in pseudowidening of the endometrium (E). N = nabothian cysts.
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Figure 12b. Pseudowidening of the endometrium. Sagittal (a) and axial (b) T2-weighted MR images show diffuse thickening of the junctional zone, aside from a central area of the dorsal myometrium. Note the blending of the fine linear hyperintense striations that extend out into the ventral myometrium (arrows); this blending results in pseudowidening of the endometrium (E). N = nabothian cysts.
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Figure 13a. Cystic adenomyosis. (a) Coronal T2-weighted MR image shows focal thickening of the junctional zone both ventrally and dorsally (black arrows) with multiple foci of high signal intensity, findings consistent with adenomyosis. In addition, there is a well-circumscribed, cystic mass of high signal intensity with a low-signal-intensity rim in the right aspect of the ventral myometrium (white arrow). Bl = bladder. (b) Axial T1-weighted MR image shows the cystic mass (arrow), which has intermediate signal intensity and a high-signal-intensity rim. N = nabothian cyst.
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Figure 13b. Cystic adenomyosis. (a) Coronal T2-weighted MR image shows focal thickening of the junctional zone both ventrally and dorsally (black arrows) with multiple foci of high signal intensity, findings consistent with adenomyosis. In addition, there is a well-circumscribed, cystic mass of high signal intensity with a low-signal-intensity rim in the right aspect of the ventral myometrium (white arrow). Bl = bladder. (b) Axial T1-weighted MR image shows the cystic mass (arrow), which has intermediate signal intensity and a high-signal-intensity rim. N = nabothian cyst.
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Figure 14a. Cystic adenomyosis. A = diffuse adenomyosis, Cx = cervix. Sagittal T2-weighted (a), fat-suppressed T1-weighted (b), and gadolinium-enhanced fat-suppressed T1-weighted (c) MR images show a complex cystic mass originating from the dorsal myometrium (arrows). Note the variable signal intensity of the mass on the T2-weighted (a) and fat-suppressed T1-weighted (b) images, which indicates hemorrhage in differential stages of organization.
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Figure 14b. Cystic adenomyosis. A = diffuse adenomyosis, Cx = cervix. Sagittal T2-weighted (a), fat-suppressed T1-weighted (b), and gadolinium-enhanced fat-suppressed T1-weighted (c) MR images show a complex cystic mass originating from the dorsal myometrium (arrows). Note the variable signal intensity of the mass on the T2-weighted (a) and fat-suppressed T1-weighted (b) images, which indicates hemorrhage in differential stages of organization.
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Figure 14c. Cystic adenomyosis. A = diffuse adenomyosis, Cx = cervix. Sagittal T2-weighted (a), fat-suppressed T1-weighted (b), and gadolinium-enhanced fat-suppressed T1-weighted (c) MR images show a complex cystic mass originating from the dorsal myometrium (arrows). Note the variable signal intensity of the mass on the T2-weighted (a) and fat-suppressed T1-weighted (b) images, which indicates hemorrhage in differential stages of organization.
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Other signs of adenomyosis at MR imaging include lack of contour abnormality or mass effect (Figs 2b, 10, 11a, 15a), ill-defined margins between normal and abnormal myometrium (Figs 2b, 8b, 12a), and an elliptical shape of a low-signal-intensity myometrial abnormality (Figs 2b, 12a, 15a). The MR imaging signs of adenomyosis are summarized in the Table.
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Figure 15a. Adenomyoma. (a) Sagittal T2-weighted MR image shows a low-signal-intensity mass with an elliptical shape in the ventral myometrium (arrows). Poorly defined borders and lack of significant mass effect allow differentiation of this adenomyoma from a leiomyoma. E = endometrium. (Reprinted, with permission, from reference 10.) (b) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows the adenomyoma (arrows).
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Figure 15b. Adenomyoma. (a) Sagittal T2-weighted MR image shows a low-signal-intensity mass with an elliptical shape in the ventral myometrium (arrows). Poorly defined borders and lack of significant mass effect allow differentiation of this adenomyoma from a leiomyoma. E = endometrium. (Reprinted, with permission, from reference 10.) (b) Photomicrograph (hematoxylin-eosin stain) of a section through the ventral myometrium shows the adenomyoma (arrows).
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Accuracy of Diagnosis
Several studies have demonstrated MR imaging to be highly accurate in diagnosis of adenomyosis, with a sensitivity and specificity of 86%–100% and an overall accuracy of 85%–90.5% (5,6,11–14).
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DIAGNOSTIC PITFALLS
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Differentiation of adenomyosis from leiomyoma is critical because this is the most frequently encountered pitfall and the therapeutic options differ. Imaging features that favor adenomyosis instead of leiomyoma are poorly defined borders, minimal mass effect, an elliptical instead of globular shape, and absence of large vessels at the margin of the lesion (5,11) (Figs 15–17). At endovaginal US, absence of calcification, edge shadowing, and a whorled appearance and the presence of echogenic nodules or linear striations favor the diagnosis of adenomyosis (15) (Fig 16). At MR imaging, hyperintense linear striations are specific for adenomyosis. Adenomyoma, the nodular form of adenomyosis, may be indistinguishable from leiomyoma at imaging (5,12). Adenomyosis can mimic endometrial carcinoma at imaging and may result in staging errors when the two conditions coexist (16,17) (Fig 18). The appearance of myometrial contractions may closely resemble that of focal adenomyosis. Contractions can be differentiated from true myometrial disease by their transient nature and changing appearance over time (10) (Fig 19). Muscular hypertrophy may demonstrate a hypoechoic inner myometrium at endovaginal US and diffuse junctional zone thickening at MR imaging, thus mimicking the appearance of adenomyosis. Cystic adenomyosis may be mistaken for a leiomyoma with hemorrhagic degeneration or a hematometra within a noncommunicating uterine segment (Figs 13, 14).
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Figure 16a. Adenomyosis versus leiomyoma. Transverse endovaginal US scans through the uterus in different patients show extensive adenomyosis (a) and a mural leiomyoma (b) involving the dorsal myometrium. Distinguishing features of the adenomyosis (arrows in a) include poorly defined borders, lack of mass effect on the endometrium (E), and an elliptical shape. In contradistinction, the leiomyoma (large arrows in b) has edge shadowing, mass effect on the endometrium (small arrows in b), and a round shape with well-defined borders.
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Figure 16b. Adenomyosis versus leiomyoma. Transverse endovaginal US scans through the uterus in different patients show extensive adenomyosis (a) and a mural leiomyoma (b) involving the dorsal myometrium. Distinguishing features of the adenomyosis (arrows in a) include poorly defined borders, lack of mass effect on the endometrium (E), and an elliptical shape. In contradistinction, the leiomyoma (large arrows in b) has edge shadowing, mass effect on the endometrium (small arrows in b), and a round shape with well-defined borders.
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Figure 17a. Adenomyosis versus leiomyoma. E = endometrium. (a) Sagittal T2-weighted MR image of a patient with adenomyosis shows thickening of the junctional zone ventrally, thus giving the appearance of an ill-defined myometrial mass (arrows). Note the minimal mass effect on the endometrial cavity and outer uterine contours relative to the size of the lesion. (b) Sagittal T2-weighted MR image of a patient with a leiomyoma shows a mass with well-defined borders (arrows) and considerable mass effect on the endometrial cavity and uterine contours. Bl = bladder.
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Figure 17b. Adenomyosis versus leiomyoma. E = endometrium. (a) Sagittal T2-weighted MR image of a patient with adenomyosis shows thickening of the junctional zone ventrally, thus giving the appearance of an ill-defined myometrial mass (arrows). Note the minimal mass effect on the endometrial cavity and outer uterine contours relative to the size of the lesion. (b) Sagittal T2-weighted MR image of a patient with a leiomyoma shows a mass with well-defined borders (arrows) and considerable mass effect on the endometrial cavity and uterine contours. Bl = bladder.
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Figure 18a. Adenomyosis versus endometrial carcinoma. Bl = bladder. (a) Sagittal T2-weighted MR image shows a small endometrial mass of intermediate signal intensity (M), a finding consistent with the clinical diagnosis of endometrial carcinoma. The abnormal signal intensity extends into the inner one-third of the myometrium dorsally (arrows). At histopathologic analysis, only microscopic myometrial invasion was present with extensive subjacent adenomyosis. (b) Axial T2-weighted MR image of another patient shows a small endometrium-based mass displacing the endometrial cavity ventrally (large straight arrow). This mass was proved to be an endometrial carcinoma with superficial myometrial invasion at histopathologic analysis. Similar-appearing abnormal areas of high signal intensity are seen in the inner aspect of the ventral myometrium (small straight arrows). These were proved to be areas of adenomyosis at histopathologic analysis. Note the associated thickening of the junctional zone ventrally, as well as the presence of a myometrial cyst (curved arrow).
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Figure 18b. Adenomyosis versus endometrial carcinoma. Bl = bladder. (a) Sagittal T2-weighted MR image shows a small endometrial mass of intermediate signal intensity (M), a finding consistent with the clinical diagnosis of endometrial carcinoma. The abnormal signal intensity extends into the inner one-third of the myometrium dorsally (arrows). At histopathologic analysis, only microscopic myometrial invasion was present with extensive subjacent adenomyosis. (b) Axial T2-weighted MR image of another patient shows a small endometrium-based mass displacing the endometrial cavity ventrally (large straight arrow). This mass was proved to be an endometrial carcinoma with superficial myometrial invasion at histopathologic analysis. Similar-appearing abnormal areas of high signal intensity are seen in the inner aspect of the ventral myometrium (small straight arrows). These were proved to be areas of adenomyosis at histopathologic analysis. Note the associated thickening of the junctional zone ventrally, as well as the presence of a myometrial cyst (curved arrow).
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Figure 19a. Myometrial contraction. (a) Transverse endovaginal US scan shows a hypoechoic, elliptical mass within the inner half of the ventral myometrium (arrows). The mass results in distortion of the endometrial cavity (E). (b) Transverse endovaginal US scan obtained 30 minutes later shows complete resolution of the mass, a finding consistent with a myometrial contraction. The echogenic contents within the endometrial cavity (between cursors) represent menstrual blood. (c) Sagittal T2-weighted MR image of another patient shows an elliptical, low-signal-intensity mass in the inner aspect of the dorsal myometrium (arrows). Note the associated distortion of the endometrium (E). These findings are consistent with a myometrial contraction.
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Figure 19b. Myometrial contraction. (a) Transverse endovaginal US scan shows a hypoechoic, elliptical mass within the inner half of the ventral myometrium (arrows). The mass results in distortion of the endometrial cavity (E). (b) Transverse endovaginal US scan obtained 30 minutes later shows complete resolution of the mass, a finding consistent with a myometrial contraction. The echogenic contents within the endometrial cavity (between cursors) represent menstrual blood. (c) Sagittal T2-weighted MR image of another patient shows an elliptical, low-signal-intensity mass in the inner aspect of the dorsal myometrium (arrows). Note the associated distortion of the endometrium (E). These findings are consistent with a myometrial contraction.
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Figure 19c. Myometrial contraction. (a) Transverse endovaginal US scan shows a hypoechoic, elliptical mass within the inner half of the ventral myometrium (arrows). The mass results in distortion of the endometrial cavity (E). (b) Transverse endovaginal US scan obtained 30 minutes later shows complete resolution of the mass, a finding consistent with a myometrial contraction. The echogenic contents within the endometrial cavity (between cursors) represent menstrual blood. (c) Sagittal T2-weighted MR image of another patient shows an elliptical, low-signal-intensity mass in the inner aspect of the dorsal myometrium (arrows). Note the associated distortion of the endometrium (E). These findings are consistent with a myometrial contraction.
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CONCLUSIONS
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With the advent of high-resolution imaging techniques, adenomyosis can be diagnosed with a high degree of accuracy. The imaging signs demonstrated with endovaginal US and MR imaging correspond closely to the varied
appearances of this disease at histopathologic analysis. Sonologists and sonographers should familiarize themselves with the endovaginal US appearance of this disease. Endovaginal US can be used as the initial imaging modality in patients suspected of having adenomyosis, but US must be performed meticulously and in real time. MR imaging can be reserved for cases that are indeterminate at endovaginal US and for patients who will undergo uterus-sparing surgery.
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References
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Abstract
INTRODUCTION
