Purpose The aim of this study is to develop and optimize an adiabatic $$$ {\mathrm{T}}_{1\uprho} $$$ ( $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$) mapping method for robust quantification of spin-lock (SL) relaxation in the myocardium at 3T. Methods Adiabatic SL (aSL) preparations were optimized for resilience against $$$ {\mathrm{B}}_0 $$$ and $$$ {\mathrm{B}}_1^{+} $$$ inhomogeneities using Bloch simulations. Optimized $$$ {\mathrm{B}}_0 $$$-aSL, Bal-aSL and $$$ {\mathrm{B}}_1 $$$-aSL modules, each compensating for different inhomogeneities, were first validated in phantom and human calf. Myocardial $$$ {\mathrm{T}}_{1\uprho} $$$ mapping was performed using a single breath-hold cardiac-triggered bSSFP-based sequence. Then, optimized $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ preparations were compared to each other and to conventional SL-prepared $$$ {\mathrm{T}}_{1\uprho} $$$ maps (RefSL) in phantoms to assess repeatability, and in 13 healthy subjects to investigate image quality, precision, reproducibility and intersubject variability. Finally, aSL and RefSL sequences were tested on six patients with known or suspected cardiovascular disease and compared with LGE, $$$ {\mathrm{T}}_1 $$$, and ECV mapping. Results The highest $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ preparation efficiency was obtained in simulations for modules comprising 2 HS pulses of 30 ms each. In vivo $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ maps yielded significantly higher quality than RefSL maps. Average myocardial $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ values were 183.28 $$$ \pm $$$ 25.53 ms, compared with 38.21 $$$ \pm $$$ 14.37 ms RefSL-prepared $$$ {\mathrm{T}}_{1\uprho} $$$. $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ maps showed a significant improvement in precision (avg. 14.47 $$$ \pm $$$ 3.71% aSL, 37.61 $$$ \pm $$$ 19.42% RefSL, p < 0.01) and reproducibility (avg. 4.64 $$$ \pm $$$ 2.18% aSL, 47.39 $$$ \pm $$$ 12.06% RefSL, p < 0.0001), with decreased inter-subject variability (avg. 8.76 $$$ \pm $$$ 3.65% aSL, 51.90 $$$ \pm $$$ 15.27% RefSL, p < 0.0001). Among aSL preparations, $$$ {\mathrm{B}}_0 $$$-aSL achieved the better inter-subject variability. In patients, $$$ {\mathrm{B}}_1 $$$-aSL preparations showed the best artifact resilience among the adiabatic preparations. $$$ {\mathrm{T}}_{1\uprho, \mathrm{adiab}} $$$ times show focal alteration colocalized with areas of hyper-enhancement in the LGE images. Conclusion Adiabatic preparations enable robust in vivo quantification of myocardial SL relaxation times at 3T.

Purpose: To develop and evaluate a robust cardiac mapping sequence at 3 T, using Bloch–Siegert shift (BSS)‐based preparations.Methods: A longitudinal magnetization preparation module was designed to encode . After magnetization tip‐down, off‐resonant Fermi pulses, placed symmetrically around two refocusing pulses, induced BSS, followed by tipping back of the magnetization. Bloch simulations were used to optimize refocusing pulse parameters and to assess the mapping sensitivity. Relaxation‐induced error was simulated for various / times. The effective mapping range was determined in phantom experiments, and maps were compared to the conventional BSS method and subadiabatic hyperbolic‐secant 8 (HS8) pulse‐sensitized method. Cardiac maps were acquired in healthy subjects, and evaluated for repeatability and imaging plane intersection consistency. The technique was modified for three‐dimensional (3D) acquisition of the whole heart in a single breath‐hold, and compared to two‐dimensional (2D) acquisition.Results: Simulations indicate that the proposed preparation can be tailored to achieve high mapping sensitivity across various ranges, with maximum sensitivity at the upper range. /‐induced bias did not exceed 5.2. Experimentally reproduced sensitization closely matched simulations for (mean difference 0.0310.022, compared to 0.0180.025 in the HS8‐sensitized method), and showed 20‐fold reduction in the standard deviation of repeated scans, compared with conventional BSS mapping, and an equivalent 2‐fold reduction compared with HS8‐sensitization. Robust cardiac map quality was obtained, with an average test‐retest variability of 0.0270.043 relative to normalized magnitude, and plane intersection bias of 0.0520.031. 3D acquisitions showed good agreement with 2D scans (mean absolute deviation 0.0550.061).Conclusion: BSS‐based preparations enable robust and tailorable 2D/3D cardiac mapping at 3 T in a single breath‐hold.

Purpose: To optimize Relaxation along a Fictitious Field (RAFF) pulses for rotating frame relaxometry with improved robustness in the presence of and field inhomogeneities.Methods: The resilience of RAFF pulses against and inhomogeneities was studied using Bloch simulations. A parameterized extension of the RAFF formulation was introduced and used to derive a generalized inhomogeneity‐resilient RAFF (girRAFF) pulse. RAFF and girRAFF preparation efficiency, defined as the ratio of the longitudinal magnetization before and after the preparation (), were simulated and validated in phantom experiments. and parametric maps were acquired at 3T in phantom, the calf muscle, and the knee cartilage of healthy subjects. The relaxation time maps were analyzed for resilience against artificially induced field inhomogeneities and assessed in terms of in vivo reproducibility.Results: Optimized girRAFF preparations yielded improved preparation efficiency (0.95/0.91 simulations/phantom) with respect to RAFF (0.36/0.67 simulations/phantom). preparations showed in phantom/calf 6.0/4.8 times higher resilience to inhomogeneities than RAFF, and a 4.7/5.3 improved resilience to inhomogeneities. In the knee cartilage, (53 14 ms) was higher than (42 11 ms). Moreover, girRAFF preparations yielded 7.6/4.9 times improved reproducibility across / inhomogeneity conditions, 1.9 times better reproducibility across subjects and 1.2 times across slices compared with RAFF. Dixon‐based fat suppression led to a further 15‐fold improvement in the robustness of girRAFF to inhomogeneities.Conclusions: RAFF pulses display residual sensitivity to off‐resonance and pronounced sensitivity to inhomogeneities. Optimized girRAFF pulses provide increased robustness and may be an appealing alternative for applications where resilience against field inhomogeneities is required.

$T_{1\rho }$ mapping is emerging as a potential, contrast-free alternative to late gadolinium enhancement (LGE) for assessment of myocardial viability. However, strong signal contributions from the blood pool can impede quantitative evaluation at the (sub)endocardium. In this work, we study the effectiveness of dark-blood (DB) contrast in adiabatic $T_{1\rho }$ ($T_{1\rho ,adiab}$) mapping at 3T, using slice-selective and non-selective adiabatic spin-lock pulses. Adiabatic DB-$T_{1\rho ,adiab}$ preparations consisted of an odd number of slice-selective adiabatic full passage (AFP) pulses, followed by a final, non-selective AFP pulse. This preparation induces $T_{1\rho ,adiab}$ decay within the imaging slice while inverting the magnetization outside. A delay ($\delta$) between preparation and imaging allowed for relaxation and inflow of the inverted blood to achieve DB contrast. Bias and precision of DB- and bright-blood (BB)-$T_{1\rho ,adiab}$ were compared in phantom and in healthy subjects (n = 10). Blood suppression efficacy and apparent myocardial thickness in DB imaging were investigated in simulations, phantom, and in vivo. The clinical feasibility of DB-$T_{1\rho ,adiab}$ mapping was evaluated in a small cohort of patients (n = 7) with suspected cardiovascular diseases. DB-$T_{1\rho ,adiab}$ values were in agreement with reference BB-$T_{1\rho ,adiab}$ values in phantom (myocardium-like vial BB: 219.27 ± 4.80 ms, DB: 218.09 ± 8.22 ms) and in healthy subjects (BB: 182.32 ± 28.27 ms, DB: 183.49 ± 45.54 ms). A moderate increase in intra-($wC{V}_{i,r}$) and inter-scan variability ($\overline{wC{V}_i}$) was observed in the DB method, compared with conventional BB imaging, for phantom and healthy subjects (in vivo $wC{V}_{i,r}$ BB: 15.51 ± 2.65%, DB: 24.82 ± 4.18%; in vivo $\overline{wC{V}_i}$ BB: 3.38 ± 0.86%, DB: 7.24 ± 2.55%). Longer delay times improved blood suppression in vivo for DB-$T_{1\rho ,adiab}$, albeit at increased intra-scan variability in phantom and in vivo (DB $wC{V}_{i,r}$ for $\delta$ = 0 ms: 4.90 ± 0.83% in phantom, 13.44 ± 2.91% in vivo, for $\delta$ = 600 ms: 8.14 ± 1.88% in phantom, 26.25 ± 5.19% in vivo). Average apparent myocardial thickness was slightly higher when using DB-$T_{1\rho ,adiab}$ compared with BB-$T_{1\rho ,adiab}$ (BB: 7.33 ± 2.05 mm, DB: 7.99 ± 2.46 mm). DB-$T_{1\rho ,adiab}$ maps yielded comparable image quality to BB-$T_{1\rho ,adiab}$ maps in patients. DB-$T_{1\rho ,adiab}$ mapping represents an alternative to BB-$T_{1\rho ,adiab}$ for myocardial assessment with the potential for improved visualization of the (sub-)endocardium.