Transient Uterine Contractions As a Potential Pathology Mimic on Premenopausal Pelvic MRI and the Role of Routine Repeat T2 Sagittal Images to Improve Observer Confidence

Introduction: Pelvic MRI has an increasingly important role in the evaluation of non-malignant uterine pathology including uterine leiomyomas, adenomyosis and endometriosis. Normal physiological myometrial junctional zone transient contractions can also be identified on MRI and have the potential to act as pathology mimics. This study aims to evaluate both the incidence of visible physiological contractions in premenopausal female pelvic MRI and also to support the routine acquisition of a repeat T2 sagittal sequence to differentiate transient physiological contractions from true underlying pathology and therefore improve observer confidence. Methods: A total of 279 female patients of child-bearing age who had undergone a pelvic MRI over a 16 month period met the inclusion criteria. All patients underwent a standard examination protocol on the same hardware. This included performing two separate T2-weighted sagittal sequences as part of the protocol firstly as the initial and then as the final series for the examination. The sagittal series were reviewed separately by four readers and conclusions made for each case with regards to the presence of identifiable contractions on one or both series and their potential to act as pathology mimics. Results: Of the 279 cases, there were 34 cases (12.2%) that were found to have transient junctional zone contractions acting as pathology mimics, resembling either leiomyomata or adenomyosis. Conclusions: Standard MRI sequences need to be able to distinguish normal transient physiological uterine contractions from true pathology to avoid diagnostic error. The routine utility of a repeat T2-weighted sagittal sequence performed at the conclusion of a patient's examination was shown to improve reader confidence in distinguishing transient contractions from true uterine pathology while adding minimal time penalty to the overall examination. It is therefore advocated that all premenopausal female pelvic MRI cases have a T2 sagittal series as the initial and then the final series as part of a routine protocol.