Rationale and objectives: The authors evaluated the value of T1 rho in relation to T1 and T2 in the characterization of human muscles.
Materials and methods: The authors studied the effect of muscle type (anterior tibial [AT] and gastrocnemius [GC]), sex, and age on 1/T1 and 1/T2 at 0.1 T and on 1/ T1 rho at locking-field B1s (spin-locking radio-frequency magnetic induction field) of 10-160 microT in 38 healthy volunteers. The contrast-to-noise ratio (CNR) between muscle and fat was evaluated with different T1-, T2-, and T1 rho-weighted magnetic resonance (MR) sequences.
Results: The 1/T1, 1/T2, and 1/T1 rho were slightly higher in AT than in GC muscles. The 1/T2 and 1/T1 rho of AT muscles showed a sex dependence, whereas no correlation with age was found. The CNR of the T1 rho-weighted images did not markedly differ from that of the T1- and T2-weighted images.
Conclusion: T1 rho is as sensitive as T2 to the composition of muscle, whereas T1 is less sensitive. In MR imaging of normal muscle, T1 rho and T2 provide a relatively similar tissue contrast.