[Proton spinlocking and T1 rho-weighted MR imaging at 1.5 T]

During spinlocking, the magnetization is aligned along an oscillating field (RF) and relaxes with time constant T1 rho, the spin-lattice relaxation time in the rotating frame. Using a clinical whole-body MR scanner, methods of spinlocking preparation and signal acquisition were combined to evaluate the potential of T1 rho-weighted MR imaging (T1 rho w-MRI) at B0 = 1.5 T. Examinations of the brain of healthy volunteers yielded images with pronounced contrast and T1 rho-variation of the tissue. However, the contrast resembled that of T2-weighted MRI, which is explained by the restricted spinlocking-field strength (BSL < or = 6 microT) on the tomograph. The result (mono-exponential fit) of serial T1 rho w-MRI data from examinations of 8 volunteers was on average 105 +/- 4 ms in the gray matter and 86 +/- 4 ms in the white matter (for BSL = 3 microT). The values are comparable to T2 of both tissues. MRT with spinlocking is less susceptible to local magnetic field inhomogeneities than conventional MRI.