éditorial

Exploration de l’endométriose pelvienne : place de l’IRMEvaluation of pelvic endometriosis: the role of MRI

Endometriosis is a common gynecological condition of unknown etiology, which mainly affects women of reproductive age. The commonest site of gastrointestinal endometriosis is the rectosigmoid colon. Involvement of the sigmoid, cecum, appendix, and small bowel are less common, but one third of rectosigmoid endometriosis is associated with right-sided extra-pelvic bowel endometriosis. Intestinal endometriosis represents one of the most severe forms of deep endometriosis (DE).

Magnetic resonance imaging (MRI) is recommended as a second-line technique in the preoperative workup of DE, especially for gastrointestinal endometriosis. An optimal MRI protocol is required for a complete mapping of endometriotic lesions. MRI could be used as a triage test in the diagnosis of rectosigmoid colon endometriosis. Magnetic resonance enterography should be additionally performed requiring a specific additional MRI protocol for the evaluation of multicentric intestinal endometriotic lesions.

Except other imaging techniques, the aim of this chapter is to expose indications for MRI, technical requirements, patient preparation, MRI protocols, and criteria for the diagnosis of intestinal endometriosis.

L’endométriose est une pathologie gynécologique fréquente d’étiologie inconnue qui affecte principalement les femmes en âge de procréer. L’imagerie de première intention est l’échographie pelvienne. Cependant, l’imagerie par résonance magnétique (IRM) est de plus en plus souvent utilisée comme bilan complémentaire dans les cas complexes et pour la planification chirurgicale. L’European Society of Urogenital Radiology et la Haute Autorité de Santé ont publié récemment des recommandations concernant le diagnostic clinique et d’imagerie de l’endométriose, la préparation des patientes, les protocoles d’IRM et les critères de compte rendu et ont développé des lignes directrices cliniques pour l’évaluation par IRM de l’endométriose pelvienne. Cet article permet de rassembler l’ensemble de ces recommandations et d’illustrer cette maladie peu connue.

Endometriosis is a common gynaecological pathology of unknown aetiology that primarily affects women of childbearing age. The first-line imaging is pelvic ultrasound. However, magnetic resonance imaging (MRI) is increasingly used as a complementary assessment in complex cases and for surgical planning. The European Society of Urogenital Radiology and the French health agency have recently published recommendations for the clinical diagnosis and imaging of endometriosis, patient preparation, MRI protocols and reporting criteria and have developed clinical guidelines for MRI evaluation of pelvic endometriosis. This article brings together all these recommendations and illustrates this little-known disease.

L’endométriose est une pathologie gynécologique fréquente d’étiologie indéterminée intéressant les femmes en période d’activité génitale. La technique de première intention est l’échographie endovaginale. Cependant, une IRM est réalisée de plus en plus fréquemment de façon complémentaire pour les dossiers complexes ou pour un bilan préopératoire. Il n’existe pas actuellement de consensus international concernant la préparation des patientes, le protocole d’IRM et les critères diagnostiques. Notre but a été de développer des recommandations cliniques pour l’évaluation par IRM de l’endométriose pelvienne basée sur les critères de la littérature et un consensus entre experts. Ce travail a été réalisé par un groupe de radiologues de la Société européenne de radiologie urogénitale (ESUR) et un gynécologue expert en méthodologie. Ce groupe a évalué les indications de l’IRM, la préparation des patientes, les protocoles IRM et les critères diagnostiques IRM pour le diagnostic d’une endométriose pelvienne. Le panel d’experts a proposé une recommandation finale pour chaque critère en utilisant les niveaux de preuve 2011 de l’Oxford Centre for Evidence Based Medicine (OCEBM).

Endometriosis is a common gynaecological condition of unknown aetiology that primarily affects women of reproductive age. The accepted first-line imaging modality is pelvic ultrasound. However, magnetic resonance imaging (MRI) is increasingly performed as an additional investigation in complex cases and for surgical planning. There is currently no international consensus regarding patient preparation, MRI protocols or reporting criteria. Our aim was to develop clinical guidelines for MRI evaluation of pelvic endometriosis based on literature evidence and consensus expert opinion. This work was performed by a group of radiologists from the European Society of Urogenital Radiology (ESUR), experts in gynaecological imaging, and a gynaecologist expert in methodology. The group discussed indications for MRI, technical requirements, patient preparation, MRI protocols and criteria for the diagnosis of pelvic endometriosis on MRI. The expert panel proposed a final recommendation for each criterion using Oxford Centre for Evidence Based Medicine (OCEBM) 2011 levels of evidence.

To evaluate the interest of rectal and vaginal filling in vaginal and recto-sigmoid endometriosis with MR imaging. To compare the results between a senior and a junior radiologist review.

Sixty-seven patients with clinically suspected deep infiltrating endometriosis were included in our MRI protocol consisting of repeated T2-weigthed sequences (axial and sagittal) before and after rectal and vaginal marking with ultrasonography gel. Vaginal and recto-sigmoid endometriosis lesions were analyzed before and after opacification. The inter-reader agreement between senior and junior scores was studied.

Concerning vaginal and muscularis and beyond colonic involvement, no significant difference (P = 0.32) was observed and the inter-reader agreement was excellent (K = 0.96 and 0.97 respectively). Concerning serosa colonic lesions, a significant difference was observed (P = 0.01) and the inter-reader agreement was poor (K = 0).

Rectal and vaginal filling in endometriosis staging with MRI is not necessary no matter the reader experiment.

Évaluer l’intérêt du remplissage rectal et vaginal dans l’endométriose vaginale et rectosigmoïdienne en IRM. Comparer ces résultats entre un radiologue senior et junior.

Soixante-sept patientes suspectées cliniquement d’endométriose pelvienne profonde ont été incluses dans notre protocole IRM qui comprenait des séquences en pondération T2 (axiale et sagittale) répétées avant et après balisage rectal et vaginal par du gel échographique. Les lésions d’endométriose vaginale et rectosigmoïdienne ont été analysées sans et après opacification. La concordance inter-observateur entre le radiologue senior et junior a été étudiée.

Concernant l’atteinte vaginale et celle de la musculeuse colique et au-delà, aucune différence significative (p = 0,32) n’a été observée et la concordance inter-observateur était excellente (K = 0,96 et 0,97 respectivement). Concernant les lésions de la séreuse colique, une différence significative (p = 0,01) a été observée et la concordance inter-observateur était mauvaise (K = 0).

L’opacification rectale et vaginale dans le bilan d’endométriose en IRM pelvienne n’est pas nécessaire et ce peu importe l’expérience du lecteur.

Ectopic endometriosis is a common condition which is often underdiagnosed, where MRI can help make a diagnosis simply, non-invasively and without irradiation. However, imagery signs of it are enormously polymorphic with a wide range of possible locations. In this paper, we have tried to illustrate comprehensively all its MRI appearances depending on the different locations where it occurs.

Determining if Magnetic Resonance Imaging (MRI) accuracy in diagnosing endometriosis is related to radiologist's expertise.

Written informed consent was obtained from all patients. This study is compliant to STARD method. Thirty patients (mean age 34; range 21–45 years) who had undergone MRI study for suspected endometriosis underwent surgery were retrospectively evaluated. MRI at 1.5 T was performed with SE and TSE sequences, T1 and T2-weighted with and without fat suppression. Four localizations were analyzed: ovary, uterosacral ligaments (USL), vaginal fornix and Rectum\Sigma\Douglas (R.S.D.). One radiologist evaluated each dataset; sensitivity, specificity, PPV and NPV, accuracy, LR+ and LR− were calculated according to the surgical results (first analysis). Dataset were then re-analyzed 12 months (second analysis) and 24 months (third analysis) later. McNemar test was applied to determine differences between the three analysis.

Sensitivity, specificity and accuracy for the ovary at the first analysis were 88.9%, 87% and 88%, at the second 92.6%, 87% and 90% whereas at the third 92.6%, 91.3% and 92%. Sensitivity, specificity and accuracy for the USLs at the first analysis were 62.5%, 76.9% and 70%, at the second 72%, 80.8% and 76% whereas at the third 80%, 84.6% and 82%. Sensitivity, specificity and accuracy for the vaginal fornix at the first analysis were 63.2%, 64.5% and 64%, at the second 73.7%, 77.4% and 76% whereas at the third 73.7%, 83.9% and 80%. Sensitivity, specificity and accuracy for the R.S.D. at the first analysis were 39.1%, 81.5% and 62%, at the second 62.5%, 85.2% and 76% whereas at the third 73.9%, 88.9% and 82%. McNemar test indicated a significant statistical difference in sensitivity in detecting nodules of endometriosis in R.S.D. between first and third analysis (p = 0.0215). The mean review time decreased (p = 0.0001).

Accuracy of MRI in diagnosing endometriosis increased with radiologist's expertise and the improvement was statistically significant in determining RSD involvement.