NOE Enhancements and T₁ Relaxation Times of Phosphorylated Metabolites in Human Calf Muscle at 1.5 Tesla

Nuclear Overhauser effect (NOE) enhancements and relaxation times of ³¹P metabolites in human calf were measured in 12 volunteers (4 men and 8 women) at 1.5 T using a dual tuned four-ring birdcage. The NOE enhancements of inorganic phosphate (P(i)), phosphocreatine (PCr), γ-, α-, and β- nucleoside triphosphate (NTP) from 19 measurements were 0.51 ± 0.10, 0.64 ± 0.03, 0.53 ± 0.03, 0.56 ± 0.08, and 0.47 ± 0.05, respectively. The relaxation times were independent of proton irradiation and from 23 measurements were 3.49 ± 0.35, 4.97 ± 0.58, 4.07 ± 0.36, 2.90 ± 0.25, and 3.61 ± 0.25 s for P(i), PCr, γ-, α-, and β-NTP, respectively. No significant differences between gender and age were observed for either NOE enhancements or relaxation times. Also, among nine volunteers, we observed no significant differences in T₁ between the coupled and decoupled cases.