British Journal of Radiology 74 (2001),556-562 © 2001 The British Institute of Radiology
Imaging features of pelvic endometriosis
N Umaria, FRCR
and
J F Olliff, FRCR
Department of Clinical Radiology, Queen Elizabeth Hospital, Birmingham B15 2TH, UK
Correspondence: Dr J F Olliff
 |
Abstract
|
|---|
Although laparoscopy remains the investigation of choice in the diagnosis of endometriosis, imaging does play a significant role in its management. This pictorial review concentrates on the techniques used in the imaging of endometriosis.
|
Introduction
|
|---|
Endometriosis is characterized by the presence of ectopic endometrial tissue outside the uterus. Originally described by Von Rokitansky in 1860 [1], endometriosis occurs in up to 10% of women and is found almost exclusively in women of reproductive age. The exact pathogenesis is unclear but theories include: (1) metaplastic transformation of peritoneal epithelium into functional endometrium; (2) peritoneal seeding by way of retrograde menstruation; and (3) endometrium in the peritoneal cavity from retrograde flow activates differentiation of mesenchymal cells (induction theory) [2].
The commonest sites for endometrial implantation within the pelvis are the ovaries, broad and round ligaments, Fallopian tubes, cervix, vagina and pouch of Douglas. The gastrointestinal tract may be involved in about 12% of cases and the urinary tract is affected in about 1%. Symptoms include pelvic pain, dysmenorrhoea and dysparunia. 30–40% of patients suffer with infertility [3].
The hallmarks of endometriosis are endometriomas (multiloculated cystic lesions), peritoneal implants (solid endometrial tissue) and adhesions.
|
Diagnosis
|
|---|
Laparoscopy
Laparoscopy is the gold standard for the diagnosis of endometriosis when black or brown/blue nodules, resulting from repeated haemorrhage and retention of haemosiderin, are seen on the peritoneal surfaces of structures around the uterus.
Serum markers
Currently available laboratory tests lack the necessary sensitivity and specificity to serve as reliable screening tests for endometriosis, although there is growing evidence that carcinoembryonic antigen CA125 may help to evaluate selected populations at risk, to follow the course of the disease and to monitor response to treatment [4].
Imaging studies
Ultrasound
High resolution images may be obtained via the transvaginal approach using a 7.5 mHz probe. Sensitivity in the detection of focal endometrial implants is poor. However, the detection of endometriomas using ultrasound is excellent, with reports of 83% sensitivity and 98% specificity. Diagnostic accuracy may be enhanced by Doppler flow studies where blood flow in endometriomas is usually pericystic with a resistive index above 0.45 [4].
There is a broad range of ultrasound appearances of endometriomas. Diffuse, low level internal echoes occur in 95% of endometriomas (Figure 1
). Hyperechoic wall foci and multilocularity also point towards an endometrioma [5].
View larger version (104K):
[in this window]
[in a new window]
|
Figure 1. Transabdominal ultrasound showing a multiloculated right ovarian endometrioma containing low level echoes.
|
|
CT
Endometriomas may appear solid, cystic, or mixed solid and cystic, resulting in an overlap in the appearances with an abscess, ovarian cyst or even a malignant lesion (Figure 2). Owing to the poor specificity and high radiation dose, use of CT in the evaluation of pelvic endometriosis has been replaced by MRI.
View larger version (182K):
[in this window]
[in a new window]
|
Figure 2. Oral and intravenous contrast enhanced CT through the pelvis showing partly solid, partly cystic mass posterior to the uterus and anterior to the rectosigmoid junction (arrowheads). This was an endometrioma.
|
|
MRI
Identification of endometriomas by MRI relies on detection of pigmented haemorrhagic lesions. Signal characteristics vary according to the age of haemorrhage. (a) Typically, lesions appear hyperintense on T1 weighted spin echo (T1WSE) images and hypointense (shading) on T2 weighted turbo spin echo (T2WTSE) images owing to the presence of deoxyhaemoglobin and methaemoglobin (Figure 3). (b) Acute haemorrhage occasionally appears hypointense on T1WSE and T2WTSE sequences. (c) Old haemorrhage occasionally appears hyperintense on T1WSE and T2WTSE images [4].
View larger version (78K):
[in this window]
[in a new window]
|
Figure 3. Multiloculated left ovarian endometrioma showing (a) high signal intensity on T1 weighted spin echo axial image and (b) low signal intensity on T2 weighted turbo spin echo image (arrowheads), in keeping with the products of haemorrhage.
|
|
Multiple hyperintense lesions on T1WSE sequences, irrespective of the intensity on T2WTSE sequences, are characteristic of endometriosis. Sensitivities and specificities of 90% and 98%, respectively, have been achieved using standard T1WSE and T2WTSE sequences [6].
Endometrial implants are often small and express signal intensity similar to that of normal endometrium on both T1WSE and T2WTSE images [7]. Depending on hormonal influences, they exhibit varying degrees of haemorrhage.
MRI has poor sensitivity (27%) [8] in the detection of implants using T1WSE and T2WTSE sequences. Identification of small implants is better achieved with T1WSE fat suppressed images, increasing the sensitivity to 61% [8] (Figure 4).
View larger version (77K):
[in this window]
[in a new window]
|
Figure 4. The left pelvic endometrioma (arrow) is barely perceptible on the standard T1 weighted spin echo (T1WSE) axial image (a), but is much better appreciated as an area of high signal intensity on the T1WSE fat suppressed sequence (b) owing to the presence of methaemoglobin.
|
|
Contrast enhanced fat saturated sequences occasionally demonstrate diffuse peritoneal enhancement secondary to tiny implants, particularly in the region of the uterine ligaments and within the cul-de-sacs [3].
Adhesions are diagnosed when a clear interface between an endometrioma and adjacent organs cannot be demonstrated, although this may be difficult to recognize on MRI.
|
Sites of disease
|
|---|
Ovary
The ovaries are the commonest site of endometrial involvement and may be affected in two ways: (a) small endometrial implants may cause paraovarian scarring and adhesions; and (b) the ovary enlarges with repeated haemorrhage and evolves into a chocolate cyst.
The ovary may contain multiple loculi with fluid–fluid levels, consistent with products of repeated haemorrhage, or lesions may display homogeneous high signal on T1WSE images with multiple low signal internal linear septations.
Uterine ligaments and Fallopian tubes
Involvement of the uterine ligaments produces thickening and nodularity, which is usually palpable on physical examination. Contrast enhancement may occur due to a secondary inflammatory reaction (Figure 5).
View larger version (83K):
[in this window]
[in a new window]
|
Figure 5. Endometriosis of the round ligament. (a) T1 weighted spin echo (T1WSE) fat suppressed and (b) post-contrast T1WSE fat suppressed sequence showing enhancement of both round ligaments (arrows) owing to inflammation secondary to endometriosis. Note the two large endometriomas containing the products of haemorrhage anterior to the uterus and posterior to the right round ligament (arrowheads).
|
|
Endometriosis of the Fallopian tubes usually occurs in the subserosal layer and displays hyperintense foci on T2WTSE and post-contrast T1WSE sequences.
Detection of parametrial disease is often difficult with MRI owing to the surrounding vascular structures, although any asymmetry of signal intensity raises the suspicion of disease.
Uterus and cervix
The uterus may be affected in two ways: (a) serosal surface nodules (Figure 6), which may be manifested on contrast enhanced fat saturated MR images as diffuse peritoneal enhancement; and (b) adenomyosis, where there is invasion of the endometrium into the myometrium. Diffuse or focal widening of the junctional zone more than 5 mm in thickness confirms the diagnosis of adenomyosis. This is best seen on T2WTSE images as diffuse low intensity areas, which may be accompanied by tiny high intensity foci [9] (Figure 7).
View larger version (90K):
[in this window]
[in a new window]
|
Figure 6. Endometriosis of the serosal surface of the uterus. T1 weighted spin echo (T1WSE) (a) and T2 weighted turbo spin echo (T2WTSE) (b) sagittal images of the uterus showing mixed high and low signal foci on the posterior superior surface of the uterus (arrowheads) on T1WSE, which are of high signal intensity on T2WTSE.
|
|
View larger version (89K):
[in this window]
[in a new window]
|
Figure 7. Endometriosis of the uterus. (a) T2 weighted turbo spin echo (T2WTSE) sagittal image of the uterus showing diffuse thickening of the junctional zone (low signal intensity area) with multiple areas of high and low signal intensity in the myometrium (arrows), which remained high signal on T1 weighted spin echo (T1WSE) sequences (not shown here). Areas of mainly high signal intensity on the posterior lip of the cervix on T2WTSE as well as intermediate signal intensity on the axial T1WSE (b) sequences may represent either a further area of endometriosis or a Nabothian cyst.
|
|
Cul-de-sac
Endometriosis in the cul-de-sacs and rectovaginal septum may occur as tiny high signal foci on T1WSE weighted images (Figures 8 and 9). Thick adhesions and partial obliteration of the cul-de-sacs by scar tissue occasionally occurs with loss of the distinct interface between the structures. The presence of simple fluid here is not associated with endometriosis.
View larger version (144K):
[in this window]
[in a new window]
|
Figure 8. Endometriosis of the rectovaginal septum. T2 weighted turbo spin echo sagittal image showing high signal intensity in the region of the rectovaginal septum (arrow), which was also of high signal on T1 weighted spin echo images (not shown here).
|
|
View larger version (103K):
[in this window]
[in a new window]
|
Figure 9. Endometriosis in the pouch of Douglas. High signal intensity foci on (a) T1 weighted spin echo and (b) T2 weighted turbo spin echo sagittal sequences owing to extracellular methaemoglobin (arrows).
|
|
Other sites of endometriosis
Endometriosis of the alimentary tract usually affects the rectosigmoid colon. Unlike neoplastic lesions, the mucosa is not affected. Contrast enema examination may show a constricting or an eccentric intramural filling defect [3] (Figure 10). The ileum and appendix may also be affected.
View larger version (70K):
[in this window]
[in a new window]
|
Figure 10. Endometriosis of the bowel. (a) Double contrast barium enema examination showing extrinsic compression and puckering of the serosa (arrows) in the region of the rectosigmoid junction. (b) T1 weighted spin echo (T1WSE) and (c) T2 weighted turbo spin echo (T2WTSE) axial images through the pelvis of the same patient showing a left-sided multiloculated endometrioma (arrowheads) displaying high signal intensity and low signal intensity shading centrally on T1WSE and T2WTSE images, respectively. There are also multiple cysts in the right ovary.
|
|
The urinary tract may also be involved, with the bladder being affected in 84% of cases. Endometrial implants on the posterior wall and the dome of the bladder produce filling defects seen on intravenous urography and display multiple high signal foci on T1WSE and T2WTSE MRI (Figure 11). Ureteral involvement is less frequent, but extrinsic compression can produce obstruction.
View larger version (78K):
[in this window]
[in a new window]
|
Figure 11. Bladder endometriosis. (a) Bladder view from an intravenous urography examination showing irregularity of the dome of the bladder. (b) Coronal T1 weighted spin echo image of the same patient showing an endometrial implant in the wall of the bladder dome containing foci of high signal intensity. A further area of high signal intensity in the uterus is in keeping with adenomyosis.
|
|
|
Conclusion
|
|---|
Laparoscopy still remains the procedure of choice in the initial diagnosis of the disease, as the sole use of imaging is not sensitive or specific enough in the diagnosis of endometriosis. Ultrasound as an initial investigation may point towards pathology in the pelvis. However, MRI is now more frequently used, particularly in staging and monitoring response to treatment.
|
Acknowledgments
|
|---|
The authors would like to thank Dr Peter Guest from the Department of Radiology, Queen Elizabeth Hospital, Birmingham for kindly providing some of the images.
Received for publication March 29, 2000.
Revision received August 8, 2000.
Accepted for publication August 31, 2000.
|
References
|
|---|
Von Rokitansky C. Ueber uterusdrüsen—neubildung in uterus- und ovarial-sarcomen. Ztsch K K Gesellsch der Aerzte zu Wien 1860;37:577–81.
-
van der Linden PJQ. Theories on the pathogenesis of endometriosis. Hum Reprod 1996;11:53–65.
-
Bis KG, Vrachliotis TG, Agrawal R, Shetty AN, Maximovich A, Hricak H. Pelvic endometriosis: MR imaging spectrum with laparoscopic correlation and diagnostic pitfalls. Radiographics 1997;17:639–55.[Abstract]
-
Duleba AJ. Diagnosis of endometriosis. Obstet Gynecol Clin North Am 1997;24:331–46.[Medline]
-
Patel MD, Feldstein VA, Chen DC, Lipson SD, Filly RA. Endometriomas: diagnostic performance of US. Radiology 1999;210:739–45.[Abstract/Free Full Text]
-
Togashi K, Nishimura K, Kimura I, Tsuda Y, Yamashita K, Shibata T, et al. Endometrial cysts: diagnosis with MR imaging. Radiology 1991;180:73–8.[Abstract/Free Full Text]
-
Arrive L, Hricak H, Martin MC. Pelvic endometriosis: MR imaging. Radiology 1989;171:687–92.[Abstract/Free Full Text]
-
Ha HK, Lim YT, Kim HS, Suh TS, Song HH, Kim SJ. Diagnosis of pelvic endometriosis: fat suppressed T1 weighted vs conventional MR images. AJR 1994;163:127–31.[Abstract/Free Full Text]
-
Togashi K, Nishimura K, Itoh K, Fujisawa I, Noma S, Kanoka M, et al. Adenomyosis: diagnosis with MR imaging. Radiology 1988;166:111–4.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
T T Zacharia and M J O'Neill
Prevalence and distribution of adnexal findings suggesting endometriosis in patients with MR diagnosis of adenomyosis.
Br. J. Radiol.,
April 1, 2006;
79(940):
303 - 307.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
