title: Short-T2imaging for quantifying concentration of sodium (23Na) of bi-exponential T2relaxation.
abstract: OBJECTIVE
  This work intends to demonstrate a new method for quantifying concentration of sodium (23Na) of bi-exponential T2relaxation in patients on MRI scanners at 3.0 Tesla.
  
  
  METHODS
  Two single-quantum (SQ) sodium images acquired at very-short and short echo times (TE = 0.5 and 5.0 ms) are subtracted to produce an image of the short-T2component of the bi-exponential (or bound) sodium. An integrated calibration on the SQ and short-T2images quantifies both total and bound sodium concentrations. Numerical models were used to evaluate signal response of the proposed method to the short-T2components. MRI scans on agar phantoms and brain tumor patients were performed to assess accuracy and performance of the proposed method, in comparison with a conventional method of triple-quantum filtering.
  
  
  RESULTS
  A good linear relation (R2= 0.98) was attained between the short-T2image intensity and concentration of bound sodium. A reduced total scan time of 22 min was achieved under the SAR restriction for human studies in quantifying both total and bound sodium concentrations.
  
  
  CONCLUSIONS
  The proposed method is feasible for quantifying bound sodium concentration in routine clinical settings at 3.0 Tesla. Magn Reson Med 74:162-174, 2015. © 2014 Wiley Periodicals, Inc.
authors: MR Research Center, Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.|Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: Yongxian
authors: Y
authors: Qian
authors: Department of Radiology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors: Ashok
authors: A
authors: Panigrahy
authors: PET Center, Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: Charles M
authors: CM
authors: Laymon
authors: Department of Radiology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA.
authors: Vincent K
authors: VK
authors: Lee
authors: Department of Neurology and Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: Jan
authors: J
authors: Drappatz
authors: Department of Neurology and Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: Frank S
authors: FS
authors: Lieberman
authors: Department of Radiology, New York University, New York, New York, USA.
authors: Fernando E
authors: FE
authors: Boada
authors: PET Center, Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: James M
authors: JM
authors: Mountz
keywords: bound sodium imaging; brain tumor; short-T2 sodium imaging; sodium MRI; sodium quantification