Résumé :
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Communication n° 474. Introduction : Anaesthesia offsets part of the benefit of studying tissue function and/or metabolism noninvasively by NMR. Running NMR imaging protocols in conscious animals is an attractive alternative option. However, circumventing anesthetics is particularly challenging for cardiac imaging in small animals. Purpose : The goal of this study was to determine whether some degree of disease characterization was achievable with ultra-fast cardiac NMR imaging performed in conscious animals. Methods : Conscious hamsters were slipped into a 4.6 cm diameter cylinder, with the neck and legs immobilized. Half-Fourier single-shot FSE imaging, with outer volume suppression to improve spatial resolution and with a double, selective and non-selective, inversion module to reinforce black-blood contrast provided motion artefact-free images and an excellent visualization of cardiac anatomy. Series of double oblique views were acquired. Image acquisition time was 53 ms, with an in-plane resolution of 470*625 µmÃ. The ability of this protocol to detect alterations in cardiac anatomy and function and in myocardium texture was assessed in two pathological models: cardiomyopathic hamsters and hamsters with LAD coronary ligation. Results : Left ventricular dilatation and abnormal ejection fraction were demonstrated in cardiomyopathic hamsters. Confirming previous findings in anaesthetized animals, the NMR signal distribution was more heterogeneous in the myocardial wall of cardiomyopathic hamsters than in controls. After LAD coronary ligation, the course of infarct and scar formation was monitored during the next 3 weeks. Oedema-related myocardial signal intensity changes were detected on T2-weighed images at the acute phase. Segmental dysfunction was evidenced throughout the period of observation. Conclusion : This study demonstrates for the first time that characteristic features of cardiac pathologies can be evaluated with ultra-fast NMR imaging in conscious rodents.
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