LAUSR

T1ρ quantification has the potential to assess myocardial fibrosis without contrast agent. However, its preparation spin‐lock pulse is sensitive to B1 and B0 inhomogeneities, resulting in severe banding artifacts in the heart region, especially at high magnetic field such as 3 T. We aimed to design a robust spin‐lock (SL) preparation module that can be used in myocardial T1ρ quantification at 3 T. We used the tan/tanh pulse to tip up and tip down the magnetization in the spin‐lock preparation module (tan/tanh‐SL). Bloch simulation was used to optimize pulse shape parameters of the tan/tanh with a pulse duration (Tp) of 8, 4, and 2 ms, respectively. The designed tan/tanh‐SL modules were implemented on a 3‐T MR scanner. They were evaluated in phantom studies under three different cases of B0 and B1 inhomogeneities, and tested in cardiac T1ρ quantification of healthy volunteers. The performance of the tan/tanh‐SL was compared with the composite SL preparation pulses and the commonly used hyperbolic secant pulse for spin‐lock (HS‐SL). Feasible pulse shape parameters were obtained using Bloch simulation. Compared with HS‐SL, the quantification error of tan/tanh‐SL was reduced by 27.7% for Tp = 8 ms (mean ∆Q = 126.15 vs. 174.42) and 75.6% for Tp = 4 ms (mean ∆Q = 136.65 vs. 559.53). In the phantom study, tan/tanh‐SL was less sensitive to B1 and B0 inhomogeneity compared with composite SL pulses and HS‐SL. In cardiac T1ρ quantification, the T1ρ maps using tan/tanh‐SL showed fewer banding artifacts than using composite SL pulses and HS‐SL. The proposed tan/tanh‐SL preparation module greatly improves the robustness to B0 and B1 field inhomogeneities and can be used in cardiac T1ρ quantification at 3 T.