Abstract: Systems and methods for fast and robust quantification of magnetization transfer (MT) using off-resonance spin-lock MRI. The techniques can be insensitive to variations of the inherent relaxation rates R1 (1/T1) and R2 (1/T2) of the free-water pool and to variations of the chemical exchange pool. The techniques can also be robust in the presence of inhomogeneity in the B1 RF and/or B0 magnetic fields.

Abstract: MRI techniques provide robust imaging in the presence of inhomogeneity in the B1 (RF) and/or B0 magnetic fields. The techniques include using a magnetization prep sequence that includes an adiabatic half passage (AHP) followed by a spin-lock pulse, followed by a reverse AHP, after which a data acquisition sequence can be applied. The AHP and reverse AHP can have amplitude and frequency modulated to sweep through a region of frequency space. The RF amplitude of the AHP and reverse AHP can be designed to be equal to the spin-lock amplitude. Quantification of a magnetization relaxation parameter (e.g., T1rho) can use a modified relaxation model that accounts for relaxation effects during the reverse AHP. A dual-acquisition technique in which the reverse AHP of the second magnetization prep sequence has opposite frequency modulation to the reverse AHP of the first magnetization prep sequence can also be used.

Abstract: Systems and methods for fast and robust quantification of magnetization transfer (MT) using off-resonance spin-lock MRI. The techniques can be insensitive to variations of the inherent relaxation rates R1 (1/T1) and R2 (1/T2) of the free-water pool and to variations of the chemical exchange pool. The techniques can also be robust in the presence of inhomogeneity in the B1 RF and/or B0 magnetic fields.

Abstract: MRI techniques provide robust imaging in the presence of inhomogeneity in the B1 (RF) and/or B0 magnetic fields. The techniques include using a magnetization prep sequence that includes an adiabatic half passage (AHP) followed by a spin-lock pulse, followed by a reverse AHP, after which a data acquisition sequence can be applied. The AHP and reverse AHP can have amplitude and frequency modulated to sweep through a region of frequency space. The RF amplitude of the AHP and reverse AHP can be designed to be equal to the spin-lock amplitude. Quantification of a magnetization relaxation parameter (e.g., T1rho) can use a modified relaxation model that accounts for relaxation effects during the reverse AHP. A dual-acquisition technique in which the reverse AHP of the second magnetization prep sequence has opposite frequency modulation to the reverse AHP of the first magnetization prep sequence can also be used.