OP04.05: Dynamic magnetic resonance imaging (DMR) and three dimensional extended imaging (3DXI) in the first trimester diagnosis of placenta percreta: A three cases report

Abstract

Objectives:The cause of ultrasound scattering in tissues has been hypothesized to be related to the amount of collagen, elastin and to the structure and function of the extracellular matrix. Our prior work demonstrated that the decreased collagen concentration in cervical ripening clearly affected ultrasound scattering from the tissue. Before our work can be translated for use in humans to detect cervical changes in pregnancy, an in vivo quantitative ultrasound (QUS) methodology needed to be developed. Methods: Five timed-pregnant groups (day 15, 17, 19, 20, & 21 of pregnancy) and a non-pregnant group of randomly assigned Sprague-Dawley rats, (8 rats/group) were ultrasonically scanned under anesthesia with a 40-MHz custom miniature vaginal transducer (NIH Transducer Resource Center) then euthanized and the cervix harvested. Ultrasonic scatterer property estimates (average scatterer diameter [ASD], acoustic concentration [AC]) from the cervices were quantified and then compared to hydroxyproline, soluble collagen (uncross-linked), insoluble collagen (non-extractable) {Sircol TM assay [Biocolor, UK]}. Attenuation was measured for each cervix and used to estimate scatterer properties. The attenuation algorithm was verified via computer simulations and an ex vivo tissue sample. The attenuation accuracy was better than 15%. Results: Gestational day was correlated with cervical: ASD, AC, (P < 0.03); hydroxyproline, tropocollagen, soluble and insoluble collagen (P < 0.0001). The differences among gestational groups were very small (effect size = 0.13), suggestive of biologic variability, that is, a single QUS measurement of the cervix is less likely to detect significant changes than repeated longitudinal measurements in the same animal. Conclusions: The findings of this study will be used to guide longitudinal in vivo studies to predict and validate cervical changes during pregnancy. OP04.05Dynamic magnetic resonance imaging (DMR) and three dimensional extended imaging (3DXI) in the first trimester diagnosis of placenta percreta: A three cases report