P195 * X-ray phase-contrast synchrotron radiation-based micro-CT enables assessment of fetal cardiac anatomy, fiber orientation and vasculature in a rabbit model of intrauterine growth restriction

Background: Intrauterine growth restriction (IUGR) is associated with prenatal changes in cardiac shape and function that persist in childhood and may be associated to an increased cardiovascular mortality in adulthood. Ultrasound and MRI provide information at organ level, but their resolution is too low. Microscopy provides detail at cellular and subcellular level, but an integrated evaluation at organ level is extremely challenging. We hypothesize that X-ray phase-contrast synchrotron radiation-based micro-CT could provide information regarding detailed cardiac anatomy to better understand the cardiac remodeling in IUGR. Methods: A validated model of IUGR in New Zealand rabbit was used. Fetal hearts were formalin-fixed and ethanol-dehydrated. 3D X-ray phase-contrast synchrotron radiation-based micro-CT was performed at 7.43μm isotropic resolution (ESRF-ID19). Standard morphometric measurements were performed in a transverse view. Fiber orientation could be recognised and the change in fibers' angle was quantified. The distribution and local diameters of the coronary vessels tree were studied. Results: IUGR fetuses showed smaller and more globular hearts with thicker myocardial walls (Fig A, B) and coronary artery vessels dilatation (Fig C, D). A change in fiber orientation in IUGR hearts was observed, suggesting an increase of circumferential over longitudinal orientation. Conclusions: Our data suggest that cardiac remodeling due to IUGR affects fiber orientation and the geometry of the coronary vascular tree. These changes might explain the later increased risk of cardiovascular disease. Moreover, the unique novel technique used enables the acquisition of high resolution datasets of whole hearts at myofiber resolution, providing structural information at both organ and microscopic level. ![Figure][1] [1]: pending:yes