DIRECT MEASUREMENT OF SPIN-LATTICE RELAXATION-TIMES OF PHOSPHORUS METABOLITES IN HUMAN MYOCARDIUM

T1 values of phosphorus metabolites visible in human cardiac 31P‐MR spectra were determined in 12 volunteers at 1.5 T. Consecutive spectra were acquired with varying pulse repetition time (TR) from 1.6 to 24 s; volume selection was achieved with ISIS. T 1's of creatine phosphate (CP), [γ‐P], [α‐P], and [β‐P] ATP, 2‐3 diphosphoglycerate, and phosphodiesters were 6.1 ± 0.5, 5.4 ± 4 0.5, 5.5 ± 0.5, 5.8 ± 1.0, 7.6 ± 1.0, and 5.0 ± 1.0 s, respectively. CP/ATP ratios showed little change with varying TR; linear regression of CP/ATP vs TR was of borderline significance (r = 0.28, P = 0.06). T1'S for CP and ATP were also determined in standard solution (20 mM CP, 10 mM ATP) yielding TIcp of 8.7 ± 0.2 and T1[γ‐P]‐atpof 9.9 ± 0.7 s. Thus, T1'S for CP and ATP were similar at 1.5 T in both human heart and standard solution. In human cardiac 31P‐MR spectra, CP/ATP ratios may need little correction for partial saturation. Copyright © 1992 Wiley‐Liss, Inc., A Wiley Company