title: Sodium inversion recovery MRI on the knee joint at 7 T with an optimal control pulse.
abstract: In the field of sodium magnetic resonance imaging (MRI), inversion recovery (IR) is a convenient and popular method to select sodium in different environments. For the knee joint, IR has been used to suppress the signal from synovial fluids, which improves the correlation between the sodium signal and the concentration of glycosaminoglycans (GAGs) in cartilage tissues. For the better inversion of the magnetization vector under the spatial variations of the B0 and B1 fields, the IR sequence usually employ adiabatic pulses as the inversion pulse. On the other hand, it has been shown that RF shapes robust against the variations of the B0 and B1 fields can be generated by numerical optimization based on optimal control theory. In this work, we compare the performance of fluid-suppressed sodium MRI on the knee joint in vivo, between one implemented with an adiabatic pulse in the IR sequence and the other with the adiabatic pulse replaced by an optimal-control shaped pulse. While the optimal-control pulse reduces the RF power deposited to the body by 58%, the quality of fluid suppression and the signal level of sodium within cartilage are similar between two implementations.
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, NY 10016, United States. Electronic address: JaeSeung.Lee@nyumc.org.
authors.forename: Jae-Seung
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, NY 10016, United States.
authors.forename: Ding
authors.initials: D
authors.lastname: Xia
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, NY 10016, United States.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Madelin
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, NY 10016, United States.
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
mesh_terms: D000328:Adult; D000465:Algorithms; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000737:chemistry; D005260:Female; D005263:Femoral Artery / Q000033:anatomy & histology; D006025:Glycosaminoglycans / Q000737:chemistry; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D012964:Sodium / Q000737:chemistry*; D012975:Sodium Isotopes; D013582:Synovial Fluid / Q000737:chemistry
chemical_list: D006025:Glycosaminoglycans; D012975:Sodium Isotopes; D012964:Sodium
keywords: Fermat looped; Knee; MRI; Optimal control; Orthogonally encoded trajectories; Sodium