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ECR 2019 / C-3224
Uterine fibroid in all its states: MRI findings.
Congress: ECR 2019
Poster No.: C-3224
Type: Educational Exhibit
Keywords: Interventional vascular, Pelvis, Genital / Reproductive system female, MR, Education, Embolisation, Neoplasia
Authors: H. Hriz1, E. Younsi2, E. Ezzedine1, Z. Zaimi1, S. Mghaieth3, N. Achour1, A. Ben Miled1, N. Mnif1; 1Tunis/TN, 2Montfleury/TN, 3Tunis, tunis/TN
DOI:10.26044/ecr2019/C-3224

Findings and procedure details

       1. Reminder of the radiological anatomy of the uterine cavity:

 

Uterus occupies a medial and subperitoneal position in the female pelvis, just behind the bladder and in front of the rectum.

It is a fibromuscular organ, divided into three main anatomic segments (from superior to inferior): the fundus, corpus (body), and cervix (extends into the vagina).

Several ligaments support the uterine cavity, including the utero-ovarian ligament, the round ligament, the broad ligament, the cardinal ligament and the uterosacral ligament .  Fig. 1

  •  Broad ligament:

The broad ligament of the uterus is a double-layer fold of peritoneum that attaches the lateral portions of the uterus to the lateral pelvic sidewalls.  Fig. 2

It is divided into the mesometrium (largest portion), the mesosalpinx (mesentery of the uterine fallopian tubes), and the mesovarium (connects the ovaries to the broad ligament). 

It contains following structures:

 Fallopian tubes

 Ovaries

 Ovarian arteries

 Uterine arteries

 Round ligaments

 Suspensory (infundibulopelvic) ligaments

 Ovarian ligaments

 

It serves as mesentery to the female pelvic organs and contains blood vessels, nerves, and lymphatics. Fig. 4

Spotted in MRI by their vascular content (T1 with fat suppression and Gadolinium) Fig. 3.

  • Cardinal ligaments:

The cardinal ligaments are also known as the lateral or transverse cervical ligaments Fig. 5 .They are situated along the inferior border of the broad ligament and house the uterine artery and uterine veins.

They are common reservoir of cancerous cells.

  • Round ligaments:

Inserted on the uterine horns, anterior flap of the broad ligaments.

Fine symmetrical linear structures in hyposignal on T1 and T2 Fig. 6 Fig. 7.

In hypersignal after injection (arteriole).

Role in the anteversion of the uterine body.

  • Uterosacral ligaments:

The uterosacral ligaments are bilateral fibrous bands, which attach the lateral edges of the cervix to the anterior surface of the sacrum Fig. 8 . They appear in hyposignal on T1 and T2 Fig. 9 .

 

Position of the uterine cavity  Fig. 10 Fig. 11

 

Version:  long axis of the body of uterus / long axis of the vagina.

Flexion: long axis of the body of uterus / the long axis of the cervix. 

 

 

Fig. 10: Sagittal T2 Weighted MR image.
References: Hôpital Charles Nicolle-Tunis

Zonal radio-anatomy of the uterus: Fig. 12

MR imaging allows visualization of uterine zonal anatomy and its changes clearly. It is required to evaluate the local disease extent of gynecological disorders in both benign and malignant cases.

During the reproductive period, the uterus shows three distinct zonal layers in the uterine corpus and the cervix on T2-weighted images (WI).

  • Endometrium (1): characterized by its high signal intensity.
  • Junctional zone (JZ)(2): the inner myometrium presenting a low signal intensity
  • The outer myometrium(3) : associated with intermediate signal.
Fig. 12: Sagittal T2 Weighted MR image showing the zonal anatomie of the urterine body.
References: Hôpital Charles Nicolle-Tunis

 

       2. Figo Classification:

 

Numerous classifications of myomas can be found in the literature (Lasmar et al., 2005; Stamatellos and Bontis, 2007).

All of them take into account the degree of intramural extension and/or uterine cavity distortion.

The fibroid classification adopted by the ESGE (European Society for Gynecological Endoscopy) has the advantage of being very simple (G0 is a pedunculated intra-uterine myoma, G1 has its largest part (>50%) in the uterine cavity, and G2 has its largest part (>50%) in the myometrium). More recently, the FIGO classification was published (Munro et al., 2011), describing eight types of fibroids as well as a hybrid class (association of two types of myomas).

  • Type 0=Pedunculated, intracavitary
Fig. 14: Coronal T2 MR Weighted image. Leiomyoma type 0
References: Hôpital Charles Nicolle-Tunis
  • Type 1=Submucosal, intracavitary component> 50%
Fig. 15: Sagittal T2 MR Weighted image. Leiomyoma type Figo 1.
References: Hôpital Charles Nicolle-Tunis
  • Type 2=Submucosal, intracavitary component< 50%
Fig. 16: Sagittal T2 MR Weighted image. Leiomyome type 2
References: Hôpital Charles Nicolle-Tunis
  • Type 3= 100% intramural, contact with endometrium. 
Fig. 17: Axil T2 Weighted image. Leiomyoma Type 3.
References: Hôpital Charles Nicolle-Tunis
  • Type 4= Intramural 

                               

Fig. 18: Axial T2 MR Weighted image. Leiomyoma type 4.
References: Hôpital Charles Nicolle-Tunis
  • Type 5=Subserosal, ≥50% intramural
Fig. 19: Sagittal T2 Weighted image. Leiomyoma Figo 5
References: Hôpital Charles Nicolle-Tunis
  • Type 6= Subserosal, <50%.
Fig. 20: Sagittal T2 MR Weighted image. Leiomyoma type 6.
References: Hôpital Charles Nicolle-Tunis
  • Type 7=Subserosal, pedunculated.
Fig. 21: Coronal T2 MR Weighted image. Leiomyoma type Figo 7
References: Hôpital Charles Nicolle-Tunis
  • Type 8= Other (cervical, parasitic)
  • Hybrid= Where two numbers are given (e.g. 2–5), the first number refers to the relationship with the endometrium, while the second number refers to the relationship with the serosa ; e.g. 2–5 = Submucosal and subserosal, each with less than half the diameter in the endometrial and peritoneal cavities respectively. 
Fig. 22: Sagittal T2 MR Weighted image. Hybrid leiomyoma Figo2-5.
References: Hôpital Charles Nicolle-Tunis
  1.          3. Radiological aspects of uterine myomas:


Leiomyomas are benign tumors, composed predominantly of smooth muscle cells separated by variable amounts of fibrous connective tissue. They undergo different modifications according to several extrinsic and intrinsic factors (patient's age, hormonal status, pregnancy, oral contraception, menopausis ..) and thus they can degenerate in many ways.  Fig. 23

Ultrasound is the gold standard test for uterine fibroids, that enables easy and inexpensive confirmation in almost all instances.

 

But, when is it necessary to practice a pelvic MRI ?

MRI, due to its better soft tissue contrast, larger field-of-view and multiplanar imaging capabilities, assists clinicians in complementary pre-treatment mapping (exact origin, number and size) and monitoring uterine embolization.

It also distinguishes adnexel masses that can mimic subserosal fibroid, and detects features of malignancy that orient the diagnosis of variant fibroma or leiomyosarcoma.

To summury we indicate pelvic MRI in case of:

  • Pre-therapeutic assessment before uterine embolization
  • Optimum mapping
  • Finding an associated endometrial cancer
  • Research for associated adenomyosis
  • Myoma hypervascularized in Doppler
  • Myoma or adnexal mass?

 What is the MRI protocol ?

Based on a manuscript proposing an imaging algorithm for the work-up of uterine leiomyoma (European Society of Urogenital Radiology (ESUR) Guidelines : MR Imaging of Leiomyomas) published on February 2018.

To simplify;

 

          Basic protocol: 

  • Sagittal and axial T2W of the pelvis or Sagittal /oblique axial.
  • Axial T1W of the pelvis.

       Optionnal Sequences: ( atypical leiomyoma/features of malignancy/ pre and post embolization ...):

  • Coronal T2w.
  • T1W FS.
  • Dynamic contrast-enhanced stydy.
  • DWI stydy.
  • MR angiography (pre-embolization).

MRI findings: 

  • Typically a non-degenerate leiomyoma is isointense on T1 compared to the surrounding myometrium, and on homogeneous hyposignal on T2, with enhancement after the administration of contrast agent. These characteristic signal intensities are attributed to extensive hyalinization, which occurs in more than 60% of uterine leiomyomas.It may be associated with an edematous pseudocapsule with moderate T2 hypersignal due to venous and lymphatic obstruction.

Several  aspects can be secondarily noticed according to the type of degeneration.

  • Hyaline degeneration: appears similar to a non degenerated myoma on T1- and T2-weighted scans, because hyaline degeneration represents eosinophilic bands or plaques in the extracellular space; however, after the administration of IV contrast agent; hyaline degeneration causes decreased enhancement, particularly if three-phase dynamic scans are obtained 
  • Cystic degeneration: Fig. 24 Observed in about 4% and shows internal areas of high signal T2 (fluid signal) with a lack of contrast enhancement 
  • Myxoid degeneration : Fig. 25  is rare ; appears as cystic masses filled with gelatinous material, and will demonstrate very high T2 signal intensity and minimal enhancement. This aspect may be seen in leiomyosarcomas and other malignant tumors.
  • Red or carneous degeneration: Fig. 26 Fig. 27  Areas of high T1 signal intensity and moderate to high signal intensity on T2-weighted images with no enhancement; there can also be a hyperintense rim on T1-weighted scans.
  • Calcification: This is particularly the case of the elderly fibroma noticed among menopausal women. Usually dense and amorphous and can be confirmed on Computed-Tomography (CT).

 

Fig. 24: Sagittal T2-weighted (a) and axial T1-weighted fat saturated contrast enhanced (b)images show a bulky subserosal leiomyoma with exophytic development representing multiple areas with high T2 intensity signal and no enhancement, due to cystic degeneration.
References: Hôpital Charles Nicolle-Tunis
Fig. 25: Sagittal T2-weighted (a) and T1-weighted fat saturated contrast enhanced (b) images show an hybrid leiomyoma (FIGO 2-5) presenting areas with high T2 intensity (mucinous lakes) moderately enhanced or non enhanced giving a laminated appearance.
References: Hôpital Charles Nicolle-Tunis
Fig. 26: Hemorrhagic degeneration. Axial T1 Weigted image(e), Axial T1-weighted fat saturated image(f),Axial T2 Weighted image(g), Sagittal T1 Weighted image after gadolinium administration(h). 45 year old woman with an intramural leiomyoma (FIGO 4) presenting a moderate T2 signal intensity with increased signal on T1 after FAT SAT and not enhanced after Gadolinium administration.
References: Hôpital Charles Nicolle-Tunis
Fig. 27: 38 year old woman followed for uterine leiomyomas. MRI control six months after UAE. Sagittal T1 Weighted image before (a) and after Fat-supression(b)- Sagittal T2 Weighted image (c)- Sagittal T1 Weighted image Fatsupressed and after injection of Gadolnium (d). Multiple uterine leiomyomas with haemorrhagic necrobiosis (blue arrow) (hypersignal T1 W MR persisting after Fat-suppression) non enhanced after injection of Gadolinium (d). Size reduction, hypovascular character and high ADC value of leiomyomas predict a significant response to UAE compared to first MRI performed (not showed).
References: Hôpital Charles Nicolle-Tunis

 

Leiomyomas-variants and leiomyosarcoma:

 

In contrast to ordinary leiomyomas, leiomyoma-variants are neither well studied nor understood from an imaging perspective.

In between, there are several leiomyoma variants, such as mitotically active, cellular, and atypical leiomyomas, as well as smooth muscle tumors of uncertain malignant potential (STUMP).

Recent advances in magnetic resonance techniques have enabled the acquisition of functional information using modalities such as diffusion-weighted images (DWIs) or dynamic enhanced contrast MRI (DCE), images that help better characterize these uterine masses and detect any sign of malignancy.

An intermediate T2 signal and a high b value (1000 s/m2) signal were found in STUMPs and malignant tumors significantly more often than in benign tumors.

Using apparent diffusion coefficient values, a value less than 0.8 10-3 put the lesion in a high-risk group however an apparent diffusion coefficient value of 1.2 10-3 or higher, categorized the lesion as low risk.

Heterogeneous enhancement, although subjective , is more frequent in the malignant lesions.

In addition, a leiomyosarcoma must be suspected in front of masses with poorly defined margins, areas of hemorrhagic necrosis and marked heterogeneous enhancement.

The available evidence suggests that hypointense T1 signal, moderate T2 signal intensity, and high signal intensity on DWI are not typical findings of ordinary leiomyomas, and thus, if present, especially in combination, might raise the possibility of a leiomyoma-variant or a leiomyosarcoma.

In summary, although some MRI features indicate different types of myoma degeneration, there are no definitive imaging findings that reliably predict malignancy signs of uterine masses. Thus the diagnosis is based on the histological confirmation by noting the presence of infiltrative margins, nuclear atypia,and increased mitotic figures.

 

Fig. 28: Axial(a) and Sagittal (b) T2 MR Weighted- DW (c) -T1MR Weighted Fat-suppressed and injected image. 52year old woman referred for management of a suspected right ovarian mass seen in ultrasound. The latter was detected in MRI with an heterogeneous appearance (Red star). Intra-mural leiomyoma(Figo4), discovered fortuitly, in hyposignal T2 surrounded by a peripheral hypersignal T2 (a,c) which is restricted in diffusion (c), early and intensively enhanced after injection. The value of ADC was at 1.1 (not showed). We concluded atypical leiomyoma which necessitates histological confrontation.
References: Hôpital Charles Nicolle-Tunis

 

Fig. 29: Simplified diagram showing the characterization of uterine leiomyomas
References: I.THOMASSIN-NAGGARA - M. BAZOT- Tenon
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