Rapid-Sequence Phosphorus-31 Magnetic Resonance Spectroscopy of the Human Heart Using a 1.5-T Clinical System

Purpose: To compare a 'standard' slow phosphorus-31 magnetic resonance spectroscopy (³¹P-MRS) sequence with two faster sequences in phantoms and healthy volunteers using a 1.5-T clinical system. Material and Methods: Complete 3D localization was performed using a 2D phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. Two ³¹P-MRS rapid sequences (RS8-4: 8 × 8 phase-encoding, with an average of 4 acquisitions, and RS16-1: 16 × 16 phase-encoding, 1 acquisition) were compared with the standard sequence (StdP: 16 × 16 phase-encoding, with an average of 8 acquisitions) in phantom and healthy volunteers. Results: Acquisition time for the ³¹P-MRS procedure with StdP, RS8-4, and RS16-1 in the healthy volunteer studies ranged from 30 to 45, 3 to 5, and 3 to 5 minutes, respectively. Metabolite measurements of healthy volunteers obtained from ³¹P-MRS using RS8-4 correlated with values obtained using StdP (PCr r² = 0.63, P < 0.001; ATP r² = 0.41, P < 0.01 and PCr/ATP ratio r² = 0.25, P < 0.05). There was no correlation between StdP and RS16-1 for either ATP or the PCr/ATP ratio (r² = 0.03, P = 0.60, and r² = 0.11, p = 0.26, respectively). Reproducibility (intensity of phosphorus signal) with RS16-1 was worse than that of RS8-4 or StdP. Conclusion: ³¹P-MRS using RS8-4 may be a valid diagnostic tool for patients with cardiac diseases.