Refinement of cardiac NMR imaging in awake hamsters: proof of feasibility and characterization of cardiomyopathy

The goal of this study was to demonstrate the feasibility of cardiac NMR imaging in conscious hamsters and its usefulness in evaluating cardiac abnormalities in a small-animal model of cardiomyopathy. Awake hamsters, controls and cardiomyopathic ones (CHF 147), were immobilized in a dedicated holder. Half-Fourier single-shot FSE imaging, with outer-volume suppression and 'black-blood' contrast provided images free from motion artifact with good visualization of cardiac anatomy at any point in the cardiac cycle. Series of double-oblique views were acquired with or without electrocardiograph gating. Image acquisition time was 55 ms, with an in-plane resolution of 470 x 625 microm2. Left ventricular volumes, ejection fraction, and myocardium NMR signal heterogeneity were compared in CHF 147 and control hearts. Left ventricles of CHF 147 hamsters were dilated, as indicated by the increase in end-diastolic cavity volume (299 +/- 79 mm3 compared with the controls (141 +/- 39 mm3; P = 0.0002). Left ventricular ejection fraction was largely reduced (45 +/- 9% vs 86 +/- 4%; P < 0.0001). The NMR signal distribution at an effective echo time of 41 ms was more heterogeneous in the myocardial wall of CHF 147 hamsters than in controls (1.87 +/- 0.37 a.u. vs 0.98 +/- 0.12 a.u., respectively; P = 0.0002). This study is a refinement of animal experimentation, as it demonstrates for the first time that characteristic features of cardiac pathology can be evaluated with ultra-fast NMR imaging in conscious small rodents.