Retrospective evaluation of the mr#ENZIAN classification's applicability in the pre-operative assessment of complex endometriosis: a compartment-dependent challenge

Purpose Pelvic MRI is increasingly performed as a second-line investigation in suspected complex cases of endometriosis, to precisely localize lesions and to optimise surgical planning. To facilitate MRI evaluation and inter-disciplinary communication, several standardized structured image analysis and radiologic reporting classification systems have been proposed, including the mr#ENZIAN classification, whose applicability needs further proving.

In an attempt to further validate the #ENZIAN classification applicability to MRI, we retrospectively evaluated the results of structured and unstructured MRI analysis by #ENZIAN compartment, considering both sole lesion-detection and #ENZIAN grading, using the corresponding op#ENZIAN score as a reference and evaluating inter-rater agreement of structured mr#ENZIAN results. In total, 83 patients with surgically/histopathologically confirmed endometriosis who received a pelvic MRI within 8 months prior to surgery between 2018 and 2022 were included.

Concordance of mr#ENZIAN and op#ENZIAN results proved to be highly dependent on #ENZIAN-compartment: almost perfect agreement in locations FU, FI and others (FO); substantial agreement for lesion detection and grading in O, C and P; moderate to substantial agreement in T; moderate agreement in FB; moderate to fair agreement in A and only fair to poor agreement in B and FA. Inter-rater agreement between expert radiologists proved to be almost perfect to substantial for lesion detection and grading in most compartments, with exception of A, B and FA. There were no significant differences between results of structured and unstructured MRI evaluation.

We recommend a simplification of the mr#ENZIAN classification regarding DE, with clearer rules to differentiate and measure lesions affecting the A and B compartments. Similar content being viewed by others Data availability All data supporting the findings of this study are available within the paper. Abbreviations - AC1: - Gwet’s AC1 coefficient - CI: - Confidence intervals - DE: - Deep endometriosis - ESUR: - European society of urogenital radiology - NPA: - Negative percent agreement - PPA: - Positive percent agreement - R1: - Rater 1 - R2: - Rater 2 - SOP: - Standard operating procedure - TVUS: - Transvaginal ultrasound

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Insights Imaging 14:120. https://doi.org/10.1186/s13244-023-01466-x Author information Authors and Affiliations Contributions D.MH.: Conceptualisation, Methodology, Investigation, Writing - Original Draft & Editing, Visualisation; C.K.: Formal analysis, Writing - Review & Editing; E. JC.: Investigation; M.P.: Investigation; P.S.: Investigation; B.S.: Conceptualisation, Writing - Review & Editing; B.H.: Conceptualisation, Methodology, Investigation, Writing - Review & Editing, Supervision. Corresponding author Ethics declarations Competing interests The authors declare no competing interests. Ethical approval This retrospective study was approved by the local institutional review board (Medical University of Innsbruck, protocol-number: EK1298/2024) waiving the need for patient informed consent. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rights and permissions Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law. About this article Cite this article Morell-Hofert, D., Kremser, C., Josip-Caleta, E. et al. Retrospective evaluation of the mr#ENZIAN classification’s applicability in the pre-operative assessment of complex endometriosis: a compartment-dependent challenge. Abdom Radiol (2026). https://doi.org/10.1007/s00261-026-05445-w Received: Revised: Accepted: Published: Version of record: DOI: https://doi.org/10.1007/s00261-026-05445-w