Figure 8
Exemplary in-vivo 31P spectra with and without prospective motion compensation using a stimulated echo acquisition mode (STEAM) sequence (a,b) and an acquisition-weighted chemical shift imaging (CSI) sequence (c–f) in four volunteers (#1: a, #2: b, #3: c+d, #4: e+f) at 7 T. (a) STEAM spectra with increased SNR in the MoCo case. (b) MoCo additionally reduces signal contamination between PCr and \(\gamma\)-ATP frequencies, most likely originating from skeletal muscle of the chest wall during breathing. (c,d) CSI acquisitions with MoCo result in lower PCr signal and reduced PCr/ATP due to less PCr contribution from skeletal muscle, while providing improved discrimination of Pi and phosphodiesters. Voxels close to the chest wall with localized shimming elucidate these improvements. (e,f) Contaminating PCr signals from skeletal muscle are distinctly reduced and can be more readily separated from cardiac PCr. Acquisition parameters for STEAM were: 75 ml voxel size, TR = 3 s, TM = 7.5 ms, TE = 8.6 ms, 64 averages, triggering to end-systole; and for CSI: matrix 8 \(\times\) 16 \(\times\) 8, FoV 220 \(\times\) 220 \(\times\) 200 mm, 9.5 ml voxel size, TR > 2 s, 3 averages, triggering to end-systole.
