title: Perturbation of longitudinal relaxation rate in rotating frame (PLRF) analysis for quantification of chemical exchange saturation transfer signal in a transient state.
abstract: To develop a novel analytical method for quantification of chemical exchange saturation transfer (CEST) in the transient state. The proposed method aims to reduce the effects of non-chemical-exchange (non-CE) parameters on the CEST signal, emphasizing the effect of chemical exchange.
  
  
  
  The difference in the longitudinal relaxation rate in the rotating frame ( ΔR1ρ) was calculated based on perturbation of the Z-value by R1ρ, and a saturation-pulse-amplitude-compensated exchange-dependent relaxation rate (SPACER) was determined with a high-exchange-rate approximation. In both phantom and human subject experiments, MTRasym (representative of the traditional CEST index), ΔR1ρ, and SPACER were measured, evaluated, and compared by altering the non-CE parameters in a transient-state continuous-wave CEST sequence.
  
  
  
  In line with the theoretical expectation, our experimental data demonstrate that the effects of the non-CE parameters can be more effectively reduced using the proposed indices (  ΔR1ρ and SPACER) than using the traditional CEST index ( MTRasym).
  
  
  
  The proposed method allows for the chemical exchange weight to be better emphasized in the transient-state CEST signal, which is beneficial, in practice, for quantifying the CEST signal. Magn Reson Med 78:1711-1723, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.|Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.|Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.|Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
authors.forename: Yaoyu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Xuna
authors.initials: X
authors.lastname: Zhao
authors.affiliation: GE Healthcare China, Beijing, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.affiliation: Beijing City Key Lab for Medical Physics and Engineering, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, China.|Center for MRI Research, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.|McGovern Institute for Brain Research, Peking University, Beijing, China.
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Gao
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D055815:Young Adult
keywords: B1 correction; CEST; chemical exchange saturation transfer; repetition time; saturation time; spillover effect