Magnetic Resonance Imaging of Endometriosis: The Role of Advanced Techniques

Abstract

Endometriosis is a chronic inflammatory disease that affects about 10% of women, and it is characterized by the presence of endometrial tissue outside the uterine cavity. Associated symptoms are dyspareunia, chronic pelvic pain, and infertility. The diagnosis of endometriosis can be challenging due to various clinical and imaging presentations. Laparoscopy is the gold standard for the diagnosis, but it is an invasive procedure. The literature has increasingly promoted a switch to less invasive imaging techniques, such as ultrasound and magnetic resonance imaging (MRI). The latter, also in relation to the latest technological advances, allows a comprehensive and accurate assessment of the pelvis and it can also identify sites of endometriosis that escape laparoscopic evaluation. Furthermore, MRI has been found to be more accurate than other imaging techniques in relation to its improved sensitivity and specificity in identifying disease sites, also due to the role of new emerging sequences. This article aims to review the current role of advanced MRI applications in the assessment of endometriosis.

Keywords: diffusion weighted imaging; endometriosis; female pelvis; magnetic resonance imaging; tractography.

Figure 1

Right and left ovarian cysts showing high signal content on an axial fat-saturated T1-weighted image (a, arrow) and low signal on an axial T2-weighted image (b), suggesting hemorrhagic content. Both ovaries appear enlarged and in close relation, located in the rectouterine space (“kissing ovaries”).

Figure 2

Hypointense nodules in the pouch of Douglas on an axial T2-weighted image (a) with some small high-signal foci on a coronal T1-weighted image (b, arrow), more evident on an axial fat-saturated T1-weighted image (c, arrow), compatible with deep pelvic endometriosis with evidence of bleeding.

Figure 3

Axial pre-contrast (a) and axial post-contrast (b) images demonstrate a left pyosalpinx with an enlarged and multicystic ovary attributable to an ovarian tube abscess, both demonstrating wall enhancement.

Figure 4

Diffusion-weighted imaging at b = 800 (a) shows a hyperintense lesion (arrow) with hypointensity on ADC map (b) indicating restricted diffusion, consistent with endometrioma.

Figure 5

Example of 3D MR neurography showing lumbosacral plexus nerve roots. Images are displayed in the coronal plane. In a healthy woman (a), the fiber bundles display a homogeneous appearance and regular course bilaterally. In a woman affected by endometriosis (b), the fiber bundles display a discontinuous and partially interrupted course on the right side (arrow).

Figure 6

Fiber tracking reconstruction in two women affected by endometriosis of the posterior compartment (a,b). The fiber bundles in both cases are short, stubby, and have lots of branches.