Study question: What is the accuracy of magnetic resonance imaging (MRI) in the diagnosis of parametrial endometriosis in comparison with surgicopathological findings?
Summary answer: MRI displayed an accuracy of 96.4% in the preoperative diagnosis of parametrial involvement by deep infiltrating endometriosis (DIE).
What is known and what this paper adds: MRI is the best technique for preoperative mapping of DIE. This preliminary paper shows that T2-weighted MRI is a valuable tool for the preoperative evaluation of parametrial involvement by endometriosis.
Design: A retrospective study of an MRI database was used to identify examinations performed in women, who had a clinical suspicion of pelvic endometriosis (n=666), between 2005 and 2009 in a university medical centre in France.
Participants and setting: Exclusion criteria were previous surgery for DIE, incomplete surgical evaluation, repeat MRI examinations and incomplete MR protocol. Only symptomatic patients who underwent surgery with a pathological correlation were included (n=83). An experienced radiologist, blind to the surgical and histological findings, evaluated sagittal, axial and thin-section oblique axial MR images obtained from the 83 patients.
Data analysis method: Descriptive statistics and Fisher exact test were used.
Main findings: The prevalence of DIE and parametrial endometriosis was 76/83 (91.6%) and 12/83 (14.5%), respectively. The sensitivity, specificity, positive and negative predictive values, accuracy and positive and negative likelihood ratios for the diagnosis of parametrial endometriosis of low signal intensity on T2-weighted MRI, pelvic wall involvement and ureteral dilatation, were 83.3%, 98.6%, 90.9%, 97.2%, 96.4%, 59.2 and 0.17, 58.3%, 98.6%, 87.5%, 93.3%, 92.8%, 41.4 and 0.42 and 16.7%, 100%, 100%, 87.7%, 88%, infinity and 0.83, respectively, with the patient as the unit of analysis. BIAS AND LIMITATIONS: The study design was retrospective, and thus prone to bias. Only one experienced reader performed the analysis, so no data are available on intra- or interobserver variability. GENERALISABILITY: At present, no consensus exists on the optimal MR protocol to be used for the evaluation of DIE, thus limiting the wider implications of this study.
Study funding and competing interests: No funding was obtained for this study. The authors have no conflict of interest.