In vivo 31P-MRS at 7T by single voxel E-ISIS with GOIA selection pulses

The GOIA-HS(8,4) pulses used for ISIS localisation offered excellent slice profiles with high bandwidth (20-40kHz) similar to FOCI but at lower B1 (Fig.2) or shorter pulses (~3 ms) even in 5 cm distance to the surface coil. Large selective gradients (25mT/m) reduced the CSDE to ±1.4mm for the most important metabolites (PME to γ-ATP) independent of voxel size. Contamination tests with TR~1.2T1 revealed ~10-15% contamination for combination of ISIS+rectangular excitation, ~7-9% contamination for ISIS+BIR-4, and ~2-3% contamination for ISIS+BIR-4+E-ISIS schema. High spectral quality was achieved in vivo for small voxel sizes (2.5cm iso) in only 3:48 min measurement time. (Fig. 3) Reproducibility measurements underline the reliability of the spectral quantification of in vivo muscle spectra. The determined metabolite ratios were (mean±SD) 0.13±0.02 for Pi/PCr, 0.06±0.01 for PDE/PCr, 0.23±0.02 for γ-ATP/PCr, 0.25±0.02 for α-ATP/PCr, and 0.12±0.01 for β-ATP/PCr. In vivo 31P-MRS at 7T by single voxel E-ISIS with GOIA selection pulses