MRI of Endometriosis

Endometriosis MR

Morphologic Subtypes of Endometriosis

Superficial Endometriosis Implants (SIE)

  • <5 mm of peritoneal invasion
  • MRI appearance:
    • T1 hyperintense foci on peritoneal/serosal surfaces without T2 correlate
    • SIE disease burden underestimated by MRI

Superficial Endometriosis Implants:
Superficial Endometriosis Implants T1 Sagittal
T1 Sagittal

 

Deep Infiltrating Endometriosis (DIE)

  • >5 mm of peritoneal invasion
  • Two morphologic subtypes, often seen in

(1) Active glandular morphology

  • Hemorrhagic glandular +/- cystic tissue predominates
  • MRI appearance:
    • T1 hyperintense/T2 hypointense hemorrhagic glandular tissue +/- T1 hypointense/T2 hyperintense cysts  
Active Glandular Deep Infiltrating Endometriosis:
Active Glandular Deep Infiltrating Endometriosis T2 Axial
T2 Axial
Active Glandular Deep Infiltrating Endometriosis T1Axial
T1 Axial

(2) Chronic stromal fibrotic morphology

  • Smooth muscle hypertrophy and fibrosis predominates
  • MRI appearance:
    • T1 hypointense/T2 hypointense, linear or stellate shapes
    • May cause tethering or obliteration of spaces (fibrotic scarring across a peritoneal or retroperitoneal space bringing adjacent organs into fixed contact with one another)

Chronic Stromal Fibrotic Deep Infiltrating Endometriosis:
Chronic Stromal Fibrotic Deep Infiltrating Endometriosis
T2 Aixal

 

Endometriomas

  • Thick walled ovarian or paraovarian cysts containing blood of varying age
  • Most common manifestation of endometriosis
  • MRI appearance:
    • Homogenously T1 hyperintense / Heterogeneously T2 hypointense (T2 shading)
    • Paraovarian location, multilocular appearance, angled margins, fluid-fluid levels, and internal restricted diffusion are all possible
  • Pearls:
    • Compared to hemorrhagic cysts,
      • T2 signal is darker and more heterogenous & T1 signal is brighter and more homogenous
      • “T2 dark spot sign” (T2 hypointense/T1 hyperintense nodule) is most specific finding of endometrioma
    • Kissing Ovaries” = medialized and tethered together by paraovarian DIE
      • Indicates moderate to severe (stage III-IV) endometriosis
    • Consider malignant transformation if: enhancing nodule (most sensitive sign), nodule > 3 cm, lesion growth, loss of T2 shading from fluid produced by tumor cells
Endometrioma with T2 Dark Spot Sign (arrow)
Endometrioma with T2 dark spot sign T2 Axial
T2 Axial
Endometrioma with T2 dark spot sign T1 Axial
T1 Axial
Kissing Ovaries:
Kissing Ovaries T2 Axial
T2 Axial
Kissing Ovaries T1 Axial
T1 Axial

Compartment Based Approach

Anterior Compartment Contents

  • Prevesical space
  • Round ligaments
  • Bladder
  • Distal ureters
  • Vesicouterine/cervical/vaginal spaces
Anterior Compartment Contents

 

Middle Compartment Contents

  • Vagina
  • Uterus
  • Fallopian tubes
  • Broad ligaments
  • Ovaries
Middle Compartment Contents

 

Posterior Compartment Contents

  • Rectouterine space
  • Rectocervical/vaginal spaces
  • Uterosacral ligaments
  • Rectosigmoid colon
  • Presacral space
Posterior Compartment Contents

Common & Important Manifestations of Endometriosis

Anterior Compartment

Bladder

  • Most often involves posterior wall
  • Typically T1 isointense, T2 hypointense, demonstrates increased and delayed enhancement compared to the normal surrounding detrusor muscle
  • Report should describe:
    • Lesion size
    • Location
    • Depth of detrusor muscle invasion
    • Distance form ureterovesicular junctions (UVJs)

Active Glandular DIE of the Bladder:

Active glandular DIE of the bladder T2 Sagittal Active glandular DIE of the bladder T1 Sagittal
T2 Sagittal T1 Sagittal

Ureters

  • Distal 3-4 cm most common site of involvement. Left more common than right.
  • Two subtypes:
    • Extrinsic – abuts the ureter resulting in tethering, angular deviation, and compression (75-80% of cases of ureteral involvement)
    • Intrinsic – invades the ureter resulting in luminal narrowing and hydroureteronephrosis (20-25% of cases of ureteral involvement)
  • Report should describe:
    • Lesion size/length of ureter involved
    • Extrinsic versus intrinsic subtype
    • Absence or presence of hydroureteronephrosis
    • Location and distance from UVJ
    • Depth of invasion

Intrinsic Chronic Stromal Fibrotic DIE of the Ureter with Mild Hydroureteronephrosis:

Intrinsic chronic stromal fibrotic DIE of the ureter with mild hydroureteronephrosis T2 Coronal Ureter Intrinsic chronic stromal fibrotic DIE of the ureter with mild hydroureteronephrosis T2 Coronal Kidney
T2 Coronal Ureter T2 Coronal Kidney
Intrinsic chronic stromal fibrotic DIE of the ureter with mild hydroureteronephrosis T2 Axial  
T2 Axial  

Vesicouterine Space

  • Most common site of anterior compartment involvement
  • Causes pronounced uterine anteversion/anteflexion
  • Report should describe:
    • Lesion size
    • Presence or absence of space obliteration since this impedes laparoscopic evaluation

Chronic Stromal Fibrotic DIE with Obliteration of the Vesicouterine Space:

Chronic stromal fibrotic DIE with obliteration of the vesicouterine space T2 Sagittal
T2 Axial

 

Middle Compartment

Vagina

  • Most often involves posterior fornix
  • Can appear as nodular thickening of the vaginal wall or as a polypoid mass extending into the lumen
  • Report should describe:
    • Lesion size
    • Location
    • Depth of invasion
    • Vaginal cuff tethering, if present

Active Glandular DIE of the Posterior Vaginal Forinx:

Active glandular DIE of the posterior vaginal forinx T2 Sagittal Active glandular DIE of the posterior vaginal forinx T1 Sagittal
T2 Sagittal T1 Saggital

Fallopian Tubes

  • Hematosalpinx, a dilated fallopian tube filled with hemorrhagic products, may be the only finding of endometriosis
  • Appears as a T2 hypointense/T1 hyperintense tubular structure in the adnexa

Hematosalpinx:

Hematosalpinx T2 Axial Hematosalpinx T1 Axial
T2 Axial T1 Axial

Uterus

  • Uterine version and flexion can be exaggerated by DIE
  • Torus uterinus (junction of the uterine corpus and the cervix along the posterior serosa/origin of the uterosacral ligaments) is a very common site of involvement
  • Report should describe:
    • Uterine version (angle of the uterus relative to the angle of the vagina)
    • Uterine flexion (angle of the uterine body relative to the angle of the cervix)
    • Lesion size
    • Lesion location
    • Depth of invasion from the serosa into the myometrium
    • Distance from innermost point of invasion to the endometrium

Mixed Active Glandular and Chronic Stromal Fibrotic DIE of the Torus Uterinus:

Mixed active glandular and chronic stromal fibrotic DIE of the torus uterinus T2 Sagittal Mixed active glandular and chronic stromal fibrotic DIE of the torus uterinus T1 Sagittal
T2 Sagittal T1 Sagittal

 

Posterior Compartment

Rectouterine/Cervical Space

  • Causes pronounced uterine retroversion/retroflexion
  • Report should describe:
    • Lesion size
    • Presence or absence of space obliteration since this impedes laparoscopic evaluation
    • If rectovaginal disease is present, since this is extraperitoneal and requires a deeper dissection during laparoscopy

Chronic Stromal Fibrotic DIE of the Rectocervical Space:

Chronic Stromal Fibrotic DIE of the rectocervical space T2 Sagittal Chronic Stromal Fibrotic DIE of the rectocervical space T2 Axial
T2 Sagittal T2 Axial

Uterosacral Ligaments

  • Extends from the torus uterinus towards the sacrum
  • Most common site of posterior compartment involvement 
  • Appears as asymmetric thickening, nodularity, and shortening
  • Report should describe:
    • Whether thickening appears smooth or irregular/nodular
Uterosacral ligaments T2 Axial
T2 Axial

Rectosigmoid Colon

  • Rectum & sigmoid colon account for 90% of bowel endometriosis
  • Terminal ileum is the most common location of small bowel involvement
  • Can appear as:
    • Wall thickening or a mass
    •  “Mushroom cap” of muscularis propria hypertrophy surrounding a serosal DIE implant
  • Treatment:
    • discoid resection if < 50% circumference involved
    • segmental resection if > 50% of circumference involved, liminal narrowing, or multifocal
  • Report should describe:
    • Lesion location
    • Lesion size
    • Depth of invasion
    • % of circumference involved (> or < 50%)
    • Length of bowel involved
    • Distance between nodules (if multifocal)
    • Relationship to the peritoneal reflection
    • Distance to anal verge

Chronic Stromal Fibrotic DIE of the Rectum

Chronic Stromal Fibrotic DIE of the rectum T2 Sagittal Chronic Stromal Fibrotic DIE of the rectum T1 Sagittal
T2 Sagittal T1 Sagittal
Wall Thickening Mushroom Cap Sign
Chronic Stromal Fibrotic DIE of the rectum T2 Axial Chronic Stromal Fibrotic DIE of the rectum T2 Sagittal B
T2 Axial T2 Sagittal

MRI Protocol Considerations

Key sequences:

  • To evaluate for SEI = T1 weighted fat-saturated axial and sagittal
  • To evaluate for DIE = T2 weighted non-fat-saturated axial, sagittal, and coronal
  • To evaluate for endometriomas = Both listed above
  • To evaluate for malignancy or infection: DWI/ADC and contrast enhanced T1 weighted images

Additional considerations:

  • Use of an anti-peristaltic agent is highly recommended to minimize bowel motion artifact
    • 0.5-1 mg glucagon, either IM or injected IV over 1 minute
    • Hyoscyamine sulfate SL can be used in patients with a glucagon contraindication
  • Vaginal distention with 60 cc of ultrasound gel is conditionally recommended
    • typically injected by the patient
  • Rectal distension 60-180 cc of ultrasound gel is conditionally recommended
    • typically injected by a physician or other trained medical personnel
  • Moderate bladder distension is conditionally recommended

Report Template

Describe the following:

  • Uterus:
    • Version and flexion (always)
    • Adenomyosis or adenomyoma (if present)
  • Adnexa:
    • Location in the pelvis (always)
      • Are the ovaries tethered or displaced?
    • Endometrioma (if present)
    • Hydrosalpinx or hematosalpinx (if present)
  • Superficial endometriosis implants (if present)
    • Compartment and location
  • Deep endometriosis implants (if present)
    • Compartment and location
    • Morphology (active glandular or chronic stromal fibrotic)
    • Size of implant
    • Space obliteration/tethering of adjacent organs (if present)
    • Organ invasion (if present, with individual organ considerations as detailed above)

Terminology Summary

  • Superficial endometriosis implant – endometriosis implant with < 5 mm of peritoneal invasion
  • Deep infiltrating endometriosis – endometriosis implant with > 5 mm of peritoneal invasion
  • Active glandular DIE - morphology of deep infiltrating endometriosis in which hemorrhagic glandular and cystic tissue predominates
  • Chronic stromal fibrotic DIE - morphology of deep infiltrating endometriosis in which fibrosis and smooth muscle hypertrophy predominates
  • Tethering/obliteration - fibrotic scarring across a peritoneal or retroperitoneal space, bringing adjacent organs into fixed contact with one anothe
  • Endometrioma - thick walled ovarian or paraovarian cyst containing blood of varying age
  • Extrinsic ureteral involvement - DIE that abuts the ureter causing tethering and a resultant angulated course, but no invasion
  • Intrinsic ureteral involvement - DIE that invades the wall of the ureter resulting in luminal narrowing and obstruction/hydroureteronephrosis
  • Uterine version – angle of the uterus relative to the angle of the vagina: anteversion or retroversion
  • Uterine flexion – angle of the uterine body relative to the angle of the cervix: anteflexed or retroflexed
  • Torus uterinus - junction of the uterine corpus and the cervix along the posterior serosa/origin of the uterosacral ligaments
  • Vaginal Fornix - most superior reflection of the vaginal wall/recess of the vaginal lumen, formed by the protrusion of the cervix into the vaginal vault 
  • Hematosalpinx - a Fallopian tube filled with hemorrhagic products, implies the presence of endometriosis implants within the tube, tough these are not always seen

The Spaces:

  • Prevesical space – extraperitoneal space located anterior to the bladder, bounded by the transversalis fascia (anterior), the umbilicovesical fascia (posterior), the inferior border of the pubic symphysis (inferior), and the umbilicus (superior)
  • Vesicouterine space – intraperitoneal recess between the bladder (anterior) and the uterus (posterior)
  • Vesicocervical/vesicovaginal space – extraperitoneal space between the bladder (anterior), the cervix or vagina (posterior), and the vesicouterine ligaments (lateral)
  • Rectouterine space – intraperitoneal recess located between the uterus (anterior) and the upper 1/3 of the rectum (posterior)
  • Rectocervical space – intraperitoneal recess located between the cervix (anterior) and the middle 1/3 of the rectum (posterior)
  • Rectovaginal space – extraperitoneal space located between the vagina (anterior) and the lower 1/3 of the rectum (posterior), includes the posterior vaginal fornix and the rectovaginal septum

The Ligaments:

  • Broad ligaments – extends from the lateral uterus to the lateral pelvic sidewall, contains the ovary and fallopian tube, ovarian ligament, round ligament, suspensory ligament of the ovary, and the ovarian and uterine arteries
  • Cardinal ligaments – extends from the lateral cervix and vagina to the pelvic sidewall, comprised of the parametrium (superiorly/above the ureter) and the paracervix (inferiorly/below the ureter)
  • Round ligaments – originate at the superolateral aspect of the uterus just below the fallopian tubes, travel laterally through the broad ligaments, anteriorly into the inguinal canal, and inferiorly into in the labia majora
  • Canal of Nuck – distal portion of the round ligaments in the inguinal canal and labia majora
  • Uterine ligaments – umbrella term including the round ligaments, broad ligaments, and cardinal ligaments
  • Uterosacral ligaments – originates at the torus uterinus, lateral cervix, and upper vagina anteriorly, runs between the visceral and parietal layers of the mesorectal fascia along either side of the mid-rectum, and inserts onto the coccygeus, sacrospinous ligament, ischial spine, and presacral fascia between S2-S4 posteriorly

The Signs:

  • T2 Shading – decreased signal seen within an endometrioma on T2 weighted images, may or may not have a layered appearance
  • T2 dark spot sign - T2 dark/T1 bright nodule of inspissated blood products that may be found at the edge of an endometrioma
  • Kissing ovaries - medialization and tethering of the ovaries together, usually in the rectouterine space though can also occur in the vesicouterine space, implies paraovarian chronic stromal fibrotic DIE
  • Mushroom cap sign – appearance of bowel wall involvement with DIE in which there is profound muscular propria hypertrophy surrounding a serosal DIE implant, giving the appearance of a T2 hypointense mushroom cap involving the serosa and subserosal bowel wall

References

  1. P Jha, M Sakala, LP Chamie, M Feldman et al., Endometriosis MRI lexicon: consensus statement from the Society of Abdominal Radiology endometriosis disease-focused panel. Abdominal Radiology (2019) 10.1007/s00261-019-02291-x.
  2. A Darvishzadeh, W McEachern, TK Lee, P Bhosale et al., Deep pelvic endometriosis: a radiologist’s guide to key imaging features with clinical and histopathologic review. Abdominal Radiology (2016) 41:2380-400.
  3. Kaniewska M, Goloft P, Heubner M et al., Suspensory ligaments of the female genital organs: MRI evaluation with intraoperative correlation. Radiographics (2018) 38:2195-2211).
  4. A Tong, WM VanBuren, L Chamie et al., Recommendations for MRI technique in the evaluation of pelvic endometriosis: consensus statement from the Society of Abdominal Radiology endometriosis disease-focused panel. Abdominal Radiology (2020) 45:1569-86.
  5. A Jaramillo-Cardoso, AS Shenoy-Bhangle, WM VanBuren et al., Imaging of gastrointestinal endometriosis: what the radiologist should know. Abdominal Radiology (2020) 45:1694-1710.
  6. A Agely, C Bolan, A Metcalfe et al., Genitourinary manifestations of endometriosis with emphasis on the urinary tract. Abdominal Radiology (2020) 45:1711-22.

CME credit information

Title: MRI of Endometriosis
Release Date: September 7, 2022
Expiration Date: September 7, 2023
Description: Educational website with high-yield educational information and abundant imaging examples authored by Dr. Kristine Burk
Faculty:

Course Directors:
Ramin Khorasani, MD, MPH

Vice Chair, Department of Radiology, Brigham and Women’s Hospital
Professor, Harvard Medical School

Sanjay Saini, MD
Vice Chairman for Finance, MGH Imaging, Abdominal Imaging and Intervention, Department of Radiology, Massachusetts General Hospital
Professor of Radiology, Harvard Medical School

Authors:
Kristine S. Burk, MD

Department of Radiology, Brigham and Women's Hospital
Instructor in Radiology, Harvard Medical School

Leslie K. Lee, MD
Medical Director, Magnetic Resonance Imaging (MRI), Brigham and Women’s Hospital

Target Audience: This activity is intended for radiology attendings and trainees (fellows and residents) within Mass General Brigham.

Learning Objectives: Upon completion of the activity, participants will be able to identify and classify rectal cancer staging on MRI accurately and comprehensively.

Accreditation Statement:
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In support of improving patient care, Mass General Brigham is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Mass General Brigham designates this enduring activity for a maximum of 0.50 AMA PRA Category 1 CreditsTM. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

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Mass General Brigham has implemented a process to mitigate relevant financial relationships for this continuing education (CE) activity to help ensure content objectivity, independence, fair balance and ensure that the content is aligned with the interest of the public. 

The following planners have reported no relevant financial relationship with an ineligible company:
Kristine S. Burk, MD
Ramin Khorasani, MD, MPH
Kathryn Nardozza
Sanjay Saini, MD

The following planners have reported a relevant financial relationship with an ineligible company:
Atul B. Shinagare, MD
Consultant: Imaging Endpoints; Virtualscopics

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Kristine S. Burk, MD
Leslie K. Lee, MD

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