Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 20188(2):187-195 qims.amegroups.comIntroduction [626628]

© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comIntroduction
Endometriosis, which is defined as the presence of ectopic
endometrial tissue outside the uterus, is a common disease
of premenopausal women with a prevalence of 5–20% and
accounts for 20% of infertility and 24% of pelvic pain (1-5).
Although ovaries are the most common sites for ectopic
endometrial tissue implant, pelvic involvement and beyond,
such as brain and lung, can be seen. Deep infiltrating
endometriosis (DIE) is defined as subperitoneal invasion by
endometriotic lesions that exceed 5 mm in depth (6). DIE is
a common cause of pelvic pain, dysmenorrhea, dyspareunia,
dyschezia, and urinary symptoms and is associated with
infertility. Surgical treatment is required sometimes.
The diagnosis of DIE can be made through physical
examination and laparoscopic exploration, followed by
histologic confirmation. Disease extension assessment
is difficult, especially in pelvic subperitoneal sites and in regions that are obscured by pelvic adhesions (7).
T ransvaginal ultrasonography (US) is usually the first
imaging modality in diagnosis of endometriosis due to
its accessibility and low cost. However, US is operator
dependent and its poor penetration shows drawback in
detecting endometriotic lesions in some location.
MR imaging is a noninvasive and nonionizing radiation
imaging modality with high spatial resolution and excellent
tissue identification through multi-parameter sequences.
The broad field of view and multiplanar imaging allow MR
imaging to survey the whole pelvis, which can facilitate the
evaluation of lesion extension (8-10). In present pictorial
review, we will exhibit DIE at different anatomic sites with
surgical correlation.
MR imaging protocol
Patients with suspected DIE in our institution often Review Article
Deep infiltrating endometriosis MR imaging with surgical
correlation
Xue Tang1, Rennan Ling1, Jingshan Gong1, Dongdong Mei1, Yan Luo1, Minge Li2, Jianmin Xu1, Liguo Ma2
1Department of Radiology, 2Department of Gynaecology, Shenzhen People’s Hospital, Second Clinical Medical College of Jinan University,
Shenzhen 518020, China
Correspondence to: Dr. Jingshan Gong. Department of Radiology, Shenzhen People’s Hospital, Second Clinical Medical College of Jinan University,
Shenzhen 518020, China. Email: [anonimizat].
Abstract: In this pictorial review, MR imaging findings of deep infiltrating endometriosis (DIE) are
illustrated together with surgical correlation. DIE can appear as irregular nodules or plaques with similar
signal intensity to muscle on both T1-weighted and T2-weighted images. Hemorrhage foci and strands
or stellate margins are also often noted. Restriction of diffusion can be seen on diffusion-weighted image.
Fibrosis and adhesions often result in morphologic changes, such as alimentary tract tortuosity, irregular
or nodular thickening of uterosacral ligaments, and partial or complete obliteration of the pouch of
Douglas. After intravenous gadolinium contrast agent administration, homo- or heterogeneous mild to
moderate enhancement can be observed. MR imaging can depict endometriosis lesions and extension of
DIE at different anatomic locations, which is well consistent with surgical findings. Combining signal and
morphological abnormalities, MR imaging can diagnose and assess the extension of DIE with high accuracy.
MR imaging findings of DIE facilitate surgeons at treatment decision making and patient communication.
Keywords: Deep infiltrating endometriosis; MR imaging; laparoscopic findings
Submitted Nov 30, 2017. Accepted for publication Jan 19, 2018.
doi: 10.21037/qims.2018.01.10
View this article at: http://dx.doi.org/10.21037/qims.2018.01.10195

188 Tang et al. Deep infiltrating endometriosis MRI
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comundergo pelvic MR imaging with following protocol: axial
and sagittal high resolution turbo spin-echo T2-weighted
sequences, transverse turbo spin-echo T1-weighted
sequences with and without fat suppression, sagittal turbo
spin-echo T1-weighted sequences with fat suppression, and
transverse gradient-echo T1-weighted MR imaging with
and without fat suppression before and after intravenous
injection of gadolinium contrast agent with a dose of 0.2 mL
per kilogram body weight. Coronal turbo spin-echo T2-
weighted sequence and diffusion-weighted sequence are
optional decided by radiologists.
MR features of endometriosis
Endometrial cyst
Ectopic endometriotic tissues generally implant in ovaries and result in endometriotic cysts (endometriomas) during
repeated cyclic hemorrhage. The cysts typically contain
thick, old dark blood called “chocolate cyst” ( Figure 1 ).
Therefore, unlike simple cysts which are low intensity on
T1-weighted images and high intensity on T2-weighted
images, endometriomas often shows both high intensity on
T1-weighted images and T2-weighted images ( Figure 2 ).
Signal intensity of endometriomas can be low on T2-
weighted image ( Figure 3 ). A term called T2 shading sign
defined as a cystic lesion with hyperintense signal on a T1-
weighted image that demonstrates relative hypointensity on
T2-weighted image (11). This phenomenon is secondary
to the high concentration of protein and degraded blood
products that result from the repeated hemorrhage, which
shortens T2 relaxation due to susceptibility effect of
degraded blood products. This sign was reported to have a
specificity of 96% for endometriomas (12). Signal intensity
characteristics of endometrial cysts sometimes mimic fat-
containing lesions such as dermoids. Fat suppression
sequences can distinguish mature cystic teratomas from
endometrial cyst ( Figures 4,5 ). Therefore, fat suppressed
T1-weighted sequence is important in female pelvic
imaging.
Deep infiltrating endometriosis
In DIE, the ectopic endometrial foci show secretary
changes responding to circulating hormones and repeated
bleeding (13). Hemorrhage causes inflammation, which
induces histiocyte infiltration, fibromuscular hyperplasia and
adhesion. The infiltration of histiocytes results in pigment
Figure 1 Laparoscopic photo shows chocolate-like dark old blood
(arrow) spilling out after an endometriomas is cut open.
Figure 2 A 28-year-old woman with dyspareunia. (A) T ransverse T1-weighted image shows a hyperintense lesion (arrow) in the site of right
ovary; (B) sagittal T-weighted image shows the lesion is hyperintense (long arrow). A small amount of fluid in the pouch of Douglas (star),
endometriotic lesion in posterior fornix (short arrow) and Nabothian cysts of cervix (curve arrow) are noted also.
A B

189 Quantitative Imaging in Medicine and Surgery, Vol 8, No 2 March 2018
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comFigure 3 A 41-year-old woman with DIE. (A) T ransverse T1-weighted image shows a homogeneous hyperintense cyst (long arrow) in the
left ovary and a heterogeneous cyst (short arrow) with hyperintense component in the right ovary. Rectal wall involvement is seen (curve
arrow); (B) transverse T2-weighted image shows hypointensity of both ovary lesions (long arrow and short arrow) consistent with T2
shading sign.
Figure 4 A 26-year-old woman with endometrioid cyst. (A) T ransverse T1 weighted image shows several hyperintense lesions (arrows) in
the pouch of Douglas; (B) fat suppression T1-weighted image demonstrates the signal of these lesions (arrows) is not suppressed.
Figure 5 A 19-year-old girl with a mature teratoma at the right ovary and simple cyst at the left ovary. (A) T ransverse T1-weighted image
shows a lesion with hyperintensity (long arrow) at the site of right ovary and a low signal lesion (short arrow) at the pouch of Douglas; (B)
transverse T2-weighted image shows the hyperintense lesion remains as hyper intensity (long arrow), while the hypointense lesion becomes
high signal intensity (short arrow); (C) transverse fat suppression T1-weighted image demonstrates the hyperintense components on (A) are
suppressed (arrow).
A B
A B
A B C

190 Tang et al. Deep infiltrating endometriosis MRI
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comladen with hemosiderin and hemofuscin, which accounts for
hypointensity on T2 weight images, coupling with fibrosis. In
some cases, endometriosis is stromal tissue dominated with
little glands (14). Extensive adhesions can distort the normal
pelvic anatomy and obliterate the pouch of Douglas.
DIE can affect all the pelvic structures in the following
order: the rectovaginal septum and uterosacral ligaments
(69.2% of cases), the vagina (14.5%), alimentary tract
(9.9%), urinary tract (6.4%), and other extraperitoneal pelvic
sites (15). At MR imaging, the diagnosis of DIE can be
made by the joint presence of signal intensity abnormalities
and morphologic abnormalities (8). The endometrial
lesions often appear as irregular nodules or plaques with
similar signal intensity to muscle on both T1-weighted
and T2-weighted images, hemorrhage foci ( Figure 6 )
and strands or stellate margins ( Figure 7 ). Identifying
hemorrhage foci is essential, especially on fat suppressed
T1-weighted images ( Figure 8 ). Restriction of diffusion can
be seen within DIE on diffusion-weighted imaging, but
on high b value imaging it often shows mild high intensity
(Figure 9 ). After i.v. gadolinium, homo- or heterogeneous
mild to moderate enhancement may be observed ( Figure 10 ).
Fibrosis and adhesions often result in morphologic changes,
such as alimentary tract tortuosity, irregular or nodular
thickening of uterosacral ligaments, and partial or complete
obliteration of the pouch of Douglas ( Figures 11,12 ).
The morphologic abnormalities, demonstrated by MR
imaging, show well consistence with laparoscopic findings
(Figures 12,13 ). Another advantage of MR imaging is that it
can depict endometrial lesions at different anatomic sites at
single imaging, so that it can evaluate the extension of DIE
Figure 6 A 53-year-old woman with DIE. T ransverse T2-weighted
image shows an irregular hyperintense plaque (long arrow)
with multiple hyperintense foci (short arrow) in the retrocervix.
Adenomyosis (star) is demonstrated also.
Figure 7 A 37-year-old woman with DIE. Sagittal T2-weighted
image shows an irregular nodule (long arrow) with stellate margins in
the right uterosacral ligament and an endometriotic cyst (short arrow).
Figure 8 A 37-year-old woman with DIE. (A) T ransverse T1-weighted image shows irregular hypointense plaque (long arrow) with multiple
hyperintense foci at retrocervix. Thickening of bilateral uterosacral ligaments (short arrows) is noted; (B) transverse fat suppressed T1-
weighted image shows signal of the hyperintense foci (arrow) on (A) remains unchanged and is more obvious.
A B

191 Quantitative Imaging in Medicine and Surgery, Vol 8, No 2 March 2018
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comwith high accuracy (8), especially degree of alimentary tract
involvement ( Figure 14 ) and ureter ( Figure 15 ), which can
guide treatment decision.
Malignant transformation of endometriosis
Although malignant transformation of endometriosis is
rare complication with an occurrence rate of 0.6–0.8%
(16-18), the possibility should be kept in mind when a
radiologist is confronted with DIE. Contrast-enhanced
mural nodules within an endometrial cyst often suggest
malignant transformation (19). Hyperintensity due to
hemorrhage makes it difficult to identify the enhancement.
Dynamic subtraction MR imaging is useful in depicting small Figure 9 A 28-year-woman with DIE. (A) T ransverse diffusion-weighted image with a b value of 500 s/mm2 shows a hyperintense lesion (long
arrow) in the left-low abdominal wall and an endometrial cyst (short arrow) in the right ovary. (B) T ransverse diffusion-weighted image with
a b value of 1,000 s/mm2 shows the intensity of the abdominal wall lesion (long arrow) decreased and the right ovarian cyst (short arrow) as
low signal intensity.
Figure 10 A 40-year-old woman with DIE. (A) Sagittal T2-weighted image depicts an irregular fibromuscular plaque (long arrow) involving
anterior rectal wall, and an endometrial cyst (short arrow). (B) Sagittal contrast-enhanced fat-suppressed T1-weighted image shows mild
heterogeneous enhancement of rectal wall lesion (long arrow). The endometrial cyst (short arrow) is noted. (C) Photograph of gross
specimen demonstrates the endometrial lesion (arrow) penetrating the mucous layer of rectal wall.
Figure 11 A 28-year-old woman with DIE. Sagittal T2-weighted
image shows retrocervical endometriosis (arrow) and adhesion
which results in distortion of rectum.
A B
A B C

192 Tang et al. Deep infiltrating endometriosis MRI
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comFigure 12 A 38-year-old woman with DIE. (A) T ransverse T2-weighted image shows endometrial cysts (star) obliterating the pouch of
Douglas and unsymmetrical fluid (arrow); (B) laparoscopic photo demonstrates obliteration of the pouch of Douglas. The endometrial cysts
have been removed.
Figure 13 A 42-year-woman with DIE. (A) T ransverse T2-weighted image shows thickening of the right uterosacral ligament (long
arrow) and an endometrial cyst (short arrow) in the right perirectal fossa. (B) T ransverse diffusion-weighted image with a b value of
1,000 s/mm2 shows slight high signal of the right uterosacral ligament (arrow). The endometrial cyst (short arrow) in the right perirectal
fossa is heterogeneously hyperintense, which may result from T2-through effect. (C) T ransverse fat-suppressed T1-weighted image after iv
gadolinium shows mild enhancement of the left uterosacral ligament (arrow). The endometrial cyst (short arrow) in the right perirectal fossa
is noted also. (D) Sagittal fat suppressed T2-weighted image shows infiltration of the upper external aspect of the bladder wall (short arrow).
(E) Laparoscopic photo shows thickening of the right uterosacral ligament (long arrow) and several subperitoneal endometrial lesions (short
arrows).
A B
A B C
D E

193 Quantitative Imaging in Medicine and Surgery, Vol 8, No 2 March 2018
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.com
A B C
D E
Figure 14 A 37-year-old woman with DIE. (A) Sagittal T2-weighted image shows a fan-shaped hypointense mass (arrow) infiltrating the
wall of rectosigmoid; (B) transverse diffusion-weighted image shows the mass (arrow) is iso-intense to the bowel wall; (C) transverse fat-
suppressed T1-weighted image shows the mass (arrow) is iso-intense to the muscle; (D) transverse contrast-enhanced fat-suppressed T1-
weighted image shows the mass (arrow) demonstrates moderate homogenous enhancement; (E) photograph of gross specimen shows a fan-
shaped lesion infiltrating the bowel wall with an intact mucosal surface (arrow).
Figure 15 A 42-year-old woman with DIE. (A) Coronal pelvic T2-weighted image shows several endometrial cysts (long arrow) surrounding
the left ureter. Endometrial cysts (short arrow) are depicted in the pouch of Douglas; (B) coronal abdominal T2-weighted image depicts
hydronephrosis of left kidney (arrow); (C) contrast enhance transverse T1-weighted image demonstrates enhancement of the thickening left
ureter (long arrow) and an endometrial cyst with wall enhancement (short arrow).
A B C
contrast-enhanced nodule within hyperintense endometrial
lesions. Enlargement or disappearance of T2 shading of an
endometrial lesion during follow-up suggests malignant
transformation also. Diffusion-weighted imaging may also
be helpful in differentiating DIE from carcinoma (20). Carcinoma often shows high signal intensity on high b value
diffusion-weighted images, while DIE appears to be moderate
signal on high b value diffusion-weighted images ( Figure 16 ).
In summary, MR imaging can detect lesions of DIE
at different anatomic structure through visualizing signal

194 Tang et al. Deep infiltrating endometriosis MRI
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.comand morphologic abnormalities and demonstrate changes
consistent with laparoscopic findings. Combining signal
and morphological changes, MR imaging can diagnose and
evaluate extension of DIE with high accuracy, which can
support surgeons in treatment decision making and patient
consultation.
Acknowledgements
None.
Footnote
Conflicts of Interest: The authors have no conflicts of interest
to declare.
References
1. Luciano DE, Luciano AA. Management of endometriosis-related pain: an update. Womens Health (Lond Engl)
2011;7:585-590.
2. Choudhary S, Fasih N, Papadatos D, Surabhi VR.
Unusual imaging appearances of endometriosis. AJR Am J
Roentgenol 2009;192:1632-44.
3. Woodward PJ, Sohaey R, Mezzetti TP Jr. Endometriosis:
radiologic-pathologic correlation. Radiographics
2001;21:193-216.
4. Olive DL, Schwartz LB. Endometriosis. N Engl J Med
1993;328:1759-69.
5. Eskanazi B, Warner M. Epidemiology of endometriosis.
Obstet Gynecol Clin North Am 1997;24:235-58.
6. Coutinho A Jr, Bittencourt LK, Pires CE, Junqueira F ,
Lima CM, Coutinho E, Domingues MA, Domingues RC,
Marchiori E. MR imaging in deep pelvic endometriosis: a
pictorial essay. Radiographics 2011;31:549-67.
7. Kinkel K, Chapron C, Balleyguier C, Fritel X, Dubuisson
JB, Moreau JF . Magnetic resonance imaging characteristics
of deep endometriosis. Hum Reprod 1999;14:1080-6.Figure 16 A 41-year-old woman with DIE and malignant transformation of the endometrial lesion in the rectovaginal septum. (A)
Sagittal T2-weighted image shows a heterogeneous mass (arrow) in the rectovaginal septum; (B) sagittal contrast-enhanced fat-suppressed
T1-weighted image shows moderate heterogeneous enhancement (arrow); (C) transverse diffusing-weighted image with a b value of
1,000 s/mm2 shows obvious diffusion restriction (arrow); (D) photomicrograph (HE, ×100) shows atypical epithelial cells in glandular-tube-
like, stranding and papillary arrangement.
A B
C D

195 Quantitative Imaging in Medicine and Surgery, Vol 8, No 2 March 2018
© Quantitative Imaging in Medicine and Surgery. All rights reserved. Quant Imaging Med Surg 2018;8(2):187-195 qims.amegroups.com8. Bazot M, Darai E, Hourani R, Thomassin I, Cortez A,
Uzan S, Buy JN. Deep pelvic endometriosis: MR imaging
for diagnosis and prediction of extension of disease.
Radiology 2004;232:379-89.
9. Chen C, Hu YQ, Zhang XM. Magnetic resonance
imaging features of endometrial stromal sarcoma: a case
description. Quant Imaging Med Surg 2017;7:159-62.
10. Ji YF , Zhang XM, Mitchell DG, Li XH, Chen TW,
Li Y, Bao ZG, T ang W, Xiao B, Huang XH, Yang L.
Gastrointestinal tract involvement in acute pancreatitis:
initial findings and follow-up by magnetic resonance
imaging. Quant Imaging Med Surg 2017;7:641-53.
11. Glastonbury CM. The shading sign. Radiology
2002;224:199-201.
12. T ogashi K, Nishimura K, Kimura I, T suda Y, Yamashita
K, Shibata T, Nakano Y, Konishi J, Konishi I, Mori T.
Endometrial cysts: diagnosis with MR imaging. Radiology
1991;180:73-8.
13. Woodward PJ, Sohaey R, Mezzetti TP Jr. Endometriosis:
radiologic-pathologic correlation. Radiographics
2001;21:193-216.
14. Clement PB. Diseases of the peritoneum. In: Kurman RJ. editor. Blaustein’s pathology of the female genital tract. 4th
ed. New York, NY: Springer-Verlag, 1994;660-80.
15. Clement PB. Pathology of endometriosis. Pathol Annu
1990;25:245-95.
16. Heaps JM, Nieberg RK, Berek JS. Malignant neoplasms
arising in endometriosis. Obstet Gynecol 1990;75:1023-8.
17. Corner GW Jr, Hu C, Hertig AT. Ovarian carcinoma
arising in endometriosis. Am J Obstet Gynecol
1950;59:760-74.
18. Scully RE, Richardson GS, Barlow JF . The development
of malignancy in endometriosis. Clin Obstet Gynecol
1966;9:384-411.
19. T akeuchi M, Matsuzaki K, Uehara H, Nishitani H.
Malignant transformation of pelvic endometriosis: MR
imaging findings and pathologic correlation. Radiographics
2006;26:407-17.
20. Busard MP , Pieters-van den Bos IC, Mijatovic V , Van
Kuijk C, Bleeker MC, van Waesberghe JH. Evaluation
of MR diffusion-weighted imaging in differentiating
endometriosis infiltrating the bowel from colorectal
carcinoma. Eur J Radiol 2012;81:1376-80.
Cite this article as: T ang X, Ling R, Gong J, Mei D, Luo
Y, Li M, Xu J, Ma L. Deep infiltrating endometriosis MR
imaging with surgical correlation. Quant Imaging Med Surg
2018;8(2):187-195. doi: 10.21037/qims.2018.01.10