Noninvasive assessment of ectopic uterine tissue development in rats using magnetic resonance imaging

ObjectiveTo non-invasively characterize ectopic uterine tissue (EUT) development in a modified autologous rat surgical model of endometriosis using magnetic resonance imaging (MRI).DesignInvestigational MRI study.SettingA pharmaceutical company.Animal(s)Female Sprague Dawley rats.Intervention(s)Uterine tissue was autotransplanted on the right peritoneal wall of rats. Rats were serially imaged after surgery and after endogenous hormone suppression, hormone supplementation, or ovariectomy. In addition, an MRI contrast agent was administered to examine EUT perfusion characteristics.Main Outcome Measure(s)Changes in transplanted EUT volume and perfusion were monitored using MRI.Result(s)The EUT growth could be readily monitored non-invasively by MRI. Although EUT growth was rapid during the initial 4 days after surgery, volume stabilized by the third week and maintained for at least 9 weeks after transplantation. The EUT volumes varied with the estrous cycle and were hormonally sensitive to ovariectomy, to Antide (GnRH antagonist), and to Antide followed by 17β-E2 supplementation. The use of an MRI contrast agent facilitated visualization of EUT wall perfusion.Conclusion(s)MRI allows for noninvasive, dynamic evaluation of transplanted EUT growth in the rat. This reproducible model will allow for performing quantifiable pharmacologic studies in pre-clinical drug discovery for therapies targeting endometriosis.