Phosphorus (31P) Magnetic Resonance Spectroscopy at 7 Tesla in Patients with Dilated Cardiomyopathy
stoll V., clarke W., Levelt E., liu A., myerson S., robson M., neubauer S., Rodgers CT.
Purpose: This study is designed to test whether the increased 31P spectroscopy signal-to-noise ratio at 7T, compared to 3T field strength, improves precision in cardiac metabolite quantification in dilated cardiomyopathy patients. Methods: Ethical approval was obtained and participants provided written informed consent. In a prospective study design, matched phosphorus magnetic resonance spectra (31P-MRS) were acquired from 25 dilated cardiomyopathy patients at 3T and 7T. 10 healthy matched controls underwent 31P-MRS at 7T. Paired Student’s t-tests were performed to compare results between the 3T and 7T studies. Results: Phosphocreatine (PCr) SNR increased 2.5x at 7T relative to 3T. The phosphocreatine to adenosine triphosphate concentration ratio (PCr/ATP) was similar at both field strengths (1.48±0.44 at 3T vs 1.54±0.39 at 7T, P = 0.49), as expected. The Cramér-Rao lower bounds (CRLB) in PCr concentration (a measure of uncertainty in the measured ratio) decreased by 45% from 3T to 7T, reflecting the higher quality of 7T 31P spectra. DCM patients had a significantly lower PCr/ATP ratio than healthy control subjects at 7T (1.54 ± 0.39 vs 1.95 ± 0.25, P=0.005), consistent with previous findings. Conclusions: 7T cardiac 31P-MRS is demonstrated to be feasible in DCM patients, giving higher SNR and more precise quantification of the PCr/ATP ratio than at 3T. PCr/ATP was significantly lower in DCM patients than controls at 7T, consistent with previous findings at lower field strengths.