title: On-resonance variable delay multipulse scheme for imaging of fast-exchanging protons and semisolid macromolecules.
abstract: To develop an on-resonance variable delay multipulse (VDMP) scheme to image magnetization transfer contrast (MTC) and the chemical exchange saturation transfer (CEST) contrast of total fast-exchanging protons (TFP) with exchange rate above approximately 1 kHz.
  
  
  
  A train of high power binomial pulses was applied at the water resonance. The interpulse delay, called mixing time, was varied to observe its effect on the water signal reduction, allowing separation and quantification of MTC and CEST contributions as a result of their different proton transfer rates. The fast-exchanging protons in CEST and MTC are labeled together with the short T2components in MTC and separated out using a variable mixing time.
  
  
  
  Phantom studies of selected metabolite solutions (glucose, glutamate, creatine, myo-inositol), bovine serum albumin (BSA), and hair conditioner show the capability of on-resonance VDMP to separate out exchangeable protons with exchange rates above 1 kHz. Quantitative MTC and TFP maps were acquired on healthy mouse brains using this method, showing strong gray/white matter contrast for the slowly transferring MTC protons, whereas the TFP map was more uniform across the brain but somewhat higher in gray matter.
  
  
  
  The new method provides a simple way of imaging fast-exchanging protons and MTC components with a slow transfer rate. Magn Reson Med 77:730-739, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
authors.forename: Jiadi
authors.initials: J
authors.lastname: Xu
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
authors.forename: Kannie W Y
authors.initials: KW
authors.lastname: Chan
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Xu
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
authors.forename: Nirbhay
authors.initials: N
authors.lastname: Yadav
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
authors.forename: Guanshu
authors.initials: G
authors.lastname: Liu
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA.
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van Zijl
mesh_terms: D000818:Animals; D005260:Female; D005947:Glucose / Q000378:metabolism; D066128:Gray Matter / Q000000981:diagnostic imaging / Q000378:metabolism; D006203:Hair Preparations / Q000378:metabolism; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D019047:Phantoms, Imaging; D011522:Protons; D012815:Signal Processing, Computer-Assisted; D066127:White Matter / Q000000981:diagnostic imaging / Q000378:metabolism
chemical_list: D006203:Hair Preparations; D011522:Protons; D005947:Glucose
keywords: chemical exchange saturation transfer (CEST); magnetization transfer contrast (MTC); on-resonance VDMP; quantitative magnetization transfer (qMT); total fast-exchanging proton (TFP); variable delay multipulse (VDMP)