Saturation correction in human cardiac ³¹P MR spectroscopy at 1.5 T

Abstract

This study was conducted to verify the validity of using saturation factors obtained from unlocalized 31P spectra containing both chest wall and heart muscle signals for correcting human heart muscle phosphocreatine/beta-adenosine triphosphate (PCr/beta-ATP) ratios. Saturation factors and T1 relaxation times were determined from 31P magnetic resonance spectra of human chest wall and heart muscle simultaneously in healthy volunteers using one-dimensional spectroscopic imaging in combination with a two-dimensional ISIS sequence by using adiabatic 180 degrees inversion and adiabatic 90 degrees excitation pulses at 1.5 T. Blood corrected saturation factors for PCr/beta-ATP at a TR of 2.4 s were significantly different in heart muscle and chest wall muscle, 1.30 +/- 0.25 and 1.73 +/- 0.31, respectively (p < 0.05). T1 values for PCr and beta-ATP in heart muscle were 4.28 +/- 0.72 and 2.99 +/- 0.52 and in chest wall muscle 6.82 +/- 1.07 and 3.39 +/- 0.48, respectively. The T1(PCr)/T1(beta-ATP) ratios in chest wall and heart muscle were not identical. The mean PCr/beta-ATP ratios in heart and chest wall muscle of six healthy volunteers were 1.23 +/- 0.17 and 3.71 +/- 0.53, respectively.

Noninvasive measurements of cardiac high-energy phosphate metabolites in dilated cardiomyopathy by using 31P spectroscopic chemical shift imaging

“…Since chest muscles have significantly higher PCr/ATP ratios, the higher signal intensities in subvoxels close to the chest muscle (subvoxel 1 and 2) are most likely caused by partial volume effects due to voxel bleeding [22]. With small matrix sizes and the missing option of slice angulation, signal intensities of relatively remote regions can still contribute to the nominal voxel [21].…”

MR spectroscopy in heart failure—clinical and experimental findings

“…From: Neubauer et al [10] Printed with permission, American Heart Association a 31 P-standard as well as estimates of myocardial mass based on MR imaging [13] or (ii) by simultaneous acquisition of a 1 H spectrum that is used to calibrate the 31 P-signal to the tissue water proton content [14]. Finally, human 31 P-spectra also need to be corrected for the effects of partial saturation [15,16] and for the amount of blood contamination, since blood contributes signals from ATP, 2,3-diphosphoglycerate and phosphodiesters to the 31 P-heart spectrum.…”

Phosphorus-31 Two-Dimensional Chemical Shift Imaging in the Myocardium of Patients with Late Onset of Friedreich Ataxia

“…The integrals of PCr, b-ATP, and 2,3-diphosphoglycerate were determined. The spectroscopic data were corrected for T1 saturation, blood contamination, and NOE as previously recommended by several 31 P MRS studies [12,13]. PCr to b-ATP ratios were formed in order to quantitate high-energy phosphate metabolism [14].…”