Tim trio mr system

All ³¹P-MRS was performed at 3 T (Siemens Tim Trio MR system, Germany) and were acquired fasted. Volunteers were positioned prone over a modified heart/liver Siemens coil.²³ A 3D acquisition-weighted chemical shift imaging (CSI, TE=0.3 ms) sequence was used, together with an RF pulse centred between T and u resonances to reduce noise, minimise any artefact and deliver even excitation of spectra, as previously described.^{24 (link)} Voxel size was 16 × 8 × 8 mm, with field of view 240 × 240 × 200 mm. Nuclear Overhauser Enhancement was used to optimise the signal-to-noise ratio. Proton imaging was used to localise short-axis left ventricular slices. Saturation bands were placed over the skeletal muscle in the anterior chest wall, and the liver, in order to minimise potential signal contamination. The CSI grid was positioned to obtain one voxel containing mid-ventricular septal myocardium.^{24 (link)} Analysis was blinded to descriptive data, and voxels selected separately. Selected spectra were fitted using the automated processing algorithm AMARES within the jMRUI software package. The accuracy of the spectral fit was interrogated using the coefficient of variation in the PCr/ATP values based on the Cramer–Rao lower bounds. Spectra were assessed as being of satisfactory quality with a coefficient of variation under 20%.^{24 (link)}