Purpose The MP2RAGE sequence is typically optimized for either T1‐weighted uniform image (UNI) or gray matter–dominant fluid and white matter suppression (FLAWS) contrast images. Here, the purpose was to optimize an MP2RAGE protocol at 7 Tesla to provide UNI and FLAWS images simultaneously in a clinically applicable acquisition time at <0.7 mm isotropic resolution. Methods Using the extended phase graph formalism, the signal evolution of the MP2RAGE sequence was simulated incorporating T2 relaxation, diffusion, RF spoiling, and B1+ variability. Flip angles and TI were optimized at different TRs (TRMP2RAGE) to produce an optimal contrast‐to‐noise ratio for UNI and FLAWS images. Simulation results were validated by comparison to MP2RAGE brain scans of 5 healthy subjects, and a final protocol at TRMP2RAGE = 4000 ms was applied in 19 subjects aged 8–62 years with and without epilepsy. Results FLAWS contrast images could be obtained while maintaining >85% of the optimal UNI contrast‐to‐noise ratio. Using TI1/TI2/TRMP2RAGE of 650/2280/4000 ms, 6/8 partial Fourier in the inner phase‐encoding direction, and GRAPPA factor = 4 in the other, images with 0.65 mm isotropic resolution were produced in <7.5 min. The contrast‐to‐noise ratio was around 20% smaller at TRMP2RAGE = 4000 ms compared to that at TRMP2RAGE = 5000 ms; however, the 20% shorter duration makes TRMP2RAGE = 4000 ms a good candidate for clinical applications example, pediatrics. Conclusion FLAWS and UNI images could be obtained in a single scan with 0.65 mm isotropic resolution, providing a set of high‐contrast images and full brain coverage in a clinically applicable scan time. Images with excellent anatomical detail were demonstrated over a wide age range using the optimized parameter set.

Purpose This work proposes a novel RF pulse design for parallel transmit (pTx) systems to obtain uniform saturation of semisolid magnetization for magnetization transfer (MT) contrast in the presence of transmit field B1+ inhomogeneities. The semisolid magnetization is usually modeled as being purely longitudinal, with the applied B1+ field saturating but not rotating its magnetization; thus, standard pTx pulse design methods do not apply. Theory and Methods Pulse design for saturation homogeneity (PUSH) optimizes pTx RF pulses by considering uniformity of root‐mean squared B1+, B1normalrms, which relates to the rate of semisolid saturation. Here we considered designs consisting of a small number of spatially non‐selective sub‐pulses optimized over either a single 2D plane or 3D. Simulations and in vivo experiments on a 7T Terra system with an 8‐TX Nova head coil in five subjects were carried out to study the homogenization of B1normalrms and of the MT contrast by acquiring MT ratio maps. Results Simulations and in vivo experiments showed up to six and two times more uniform B1normalrms compared to circular polarized (CP) mode for 2D and 3D optimizations, respectively. This translated into 4 and 1.25 times more uniform MT contrast, consistently for all subjects, where two sub‐pulses were enough for the implementation and coil used. Conclusion The proposed PUSH method obtains more uniform and higher MT contrast than CP mode within the same specific absorption rate (SAR) budget.

The Magnetization Prepared 2 Rapid Acquisition Gradient Echoes (MP2RAGE) sequence is commonly used for 3D structural T1-weighted imaging of the brain at 7T and can be optimised to obtain UNI and clinically relevant FLuid and White Matter Suppression (FLAWS) images within one acquisition. In this study, such a protocol was used together with newly derived analytical equations accounting for partial Fourier acquisitions, and B1+ maps, in a dedicated fitting algorithm to produce quantitative T1 and arbitrarily scaled PD-maps. These maps were evaluated in children and adults at 7T demonstrating a significant T1 reduction with age.

Purpose: This work proposes a novel RF pulse design for parallel transmit (pTx) systems to obtain uniform saturation of semisolid magnetization for Magnetization Transfer (MT) contrast in the presence of transmit field (𝐵 1 + ) inhomogeneities. The semisolid magnetization is usually modeled as being purely longitudinal, with the applied 𝐵 1 + field saturating but not rotating its magnetization, thus standard pTx pulse design methods do not apply.Theory and Methods: Pulse design for Saturation Homogeneity (PUSH) optimizes pTx RF pulses by considering uniformity of root-mean squared 𝐵 1 + , 𝐵 1 𝑟𝑚𝑠 , which relates to the rate of semisolid saturation.Here we considered designs consisting of a small number of spatially non-selective sub-pulses optimized over either a single 2D plane or 3D. Simulations and in vivo experiments on a 7T Terra system with an 8-TX Nova head coil in 5 subjects were carried out to study the homogenization of 𝐵 1 𝑟𝑚𝑠 and of the MT contrast by acquiring MT ratio maps.Results: Simulations and in vivo experiments showed up to 6 and 2 times more uniform 𝐵 1 𝑟𝑚𝑠 compared to circular polarized (CP) mode for 2D and 3D optimizations, respectively. This translated into 4 and 1.25 times more uniform MT contrast, consistently for all subjects, where 2 sub-pulses were enough for the implementation and coil used. Conclusion:The proposed PUSH method obtains more uniform and higher MT contrast than CP mode within the same SAR budget.

In MT imaging, particularly at ultra-high field, results can be influenced by spatial variations in both (1) on-resonance flip angle and (2) RF saturation specified by B1rms including on- and off-resonance contributions. Conventional pulse design with parallel transmission focuses on homogenizing flip angle (&alpha;) distributions but does not explicitly account for B1rms distribution. In this work we propose a generalized pulse design framework that considers both &alpha; and B1rms and apply it to achieve uniform excitation and saturation at the same time. Performance is confirmed in phantom experiments at 7T, resulting in more uniform MTR compared to conventionally-designed pulses.