Correction of errors in estimates of T_1ρ at low spin-lock amplitudes in the presence of B₀ and B₁ inhomogeneities.

ABSTRACT: Relaxation rates R_1ρ in the rotating frame measured by spin-lock methods at very low locking amplitudes (≤ 100 Hz) are sensitive to the effects of water diffusion in intrinsic gradients and may provide information on tissue microvasculature, but accurate estimates are challenging in the presence of B₀ and B₁ inhomogeneities. Although composite pulse preparations have been developed to compensate for nonuniform fields, the transverse magnetization comprises different components and the spin-lock signals measured do not decay exponentially as a function of locking interval at low locking amplitudes. For example, during a typical preparation sequence, some of the magnetization in the transverse plane is nutated to the Z-axis and later tipped back, and so does

SUBMITTER: Zu Z 

PROVIDER: S-EPMC10619883 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature