title: Characterization and optimization of the visualization performance of continuous flow overhauser DNP hyperpolarized water MRI: Inversion recovery approach.
abstract: OBJECTIVE
  Overhauser dynamic nuclear polarization (DNP) allows the production of liquid hyperpolarized substrate inside the MRI magnet bore as well as its administration in continuous flow mode to acquire MR images with enhanced signal-to-noise ratio. We implemented inversion recovery preparation in order to improve contrast-to-noise ratio and to quantify the overall imaging performance of Overhauser DNP-enhanced MRI.
  
  
  METHODS
  The negative enhancement created by DNP in combination with inversion recovery (IR) preparation allows canceling selectively the signal originated from Boltzmann magnetization and visualizing only hyperpolarized fluid. The theoretical model describing gain of MR image intensity produced by steady-state continuous flow DNP hyperpolarized magnetization was established and proved experimentally.
  
  
  RESULTS
  A precise quantification of signal originated purely from DNP hyperpolarization was achieved. A temperature effect on longitudinal relaxation had to be taken into account to fit experimental results with numerical prediction.
  
  
  CONCLUSIONS
  Using properly adjusted IR preparation, the complete zeroing of thermal background magnetization was achieved, providing an essential increase of contrast-to-noise ratio of DNP-hyperpolarized water images. To quantify and optimize the steady-state conditions for MRI with continuous flow DNP, an approach similar to that incorporating transient-state thermal magnetization equilibrium in spoiled fast field echo imaging sequences can be used.
authors.affiliation: Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.
authors.forename: Maxim
authors.initials: M
authors.lastname: Terekhov
authors.affiliation: Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.|Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Krummenacker
authors.affiliation: Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany.
authors.forename: Vasyl
authors.initials: V
authors.lastname: Denysenkov
authors.affiliation: Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Gerz
authors.affiliation: Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Prisner
authors.affiliation: Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.
authors.forename: Laura Maria
authors.initials: LM
authors.lastname: Schreiber
mesh_terms: D000818:Animals; D001011:Aorta / Q000502:physiology; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D014867:Water
chemical_list: D014867:Water
keywords: DNP; Overhauser; TEMPOL; continuous flow; hyperpolarization