Clinically constrained optimization of flexTPI acquisition parameters for the tissue sodium concentration bioscale

The rapid transverse relaxation of the sodium magnetic resonance signal during spatial encoding causes a loss of image resolution, an effect known as T2‐blurring. Conventional wisdom suggests that spatial resolution is maximized by keeping the readout duration as short as possible to minimize T2‐blurring. Flexible twisted projection imaging performed with an ultrashort echo time, relative to T2, and a long repetition time, relative to T1, has been shown to be effective for quantitative sodium magnetic resonance imaging. A minimized readout duration requires a very large number of projections and, consequentially, results in an impractically long total acquisition time to meet these conditions. When the total acquisition time is limited to a clinically practical duration (e.g., 10 min), the optimal parameters for maximal spatial resolution of a flexible twisted projection imaging acquisition do not correspond to the shortest possible readout. Simulation and experimental results for resolution optimized acquisition parameters of quantitative sodium flexible twisted projection imaging of parenchyma and cerebrospinal fluid are presented for the human brain at 9.4 and 3.0T. The effect of signal loss during data collection on sodium quantification bias and image signal‐to‐noise ratio are discussed. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.

[1]  Wolfhard Semmler,et al.  Sodium MRI using a density‐adapted 3D radial acquisition technique , 2009, Magnetic resonance in medicine.

[2]  A. Neyrinck,et al.  Assessment of liver phagocytic activity using EPR spectrometry and imaging. , 2009, Magnetic resonance imaging.

[3]  Keith R Thulborn,et al.  Absolute molar concentrations by NMR in inhomogeneous B1. A scheme for analysis of in vivo metabolites , 1983 .

[4]  H. Gudbjartsson,et al.  The rician distribution of noisy mri data , 1995, Magnetic resonance in medicine.

[5]  Ravi S. Menon,et al.  Long component time constant of 23Na T  *2 relaxation in healthy human brain , 2004, Magnetic resonance in medicine.

[6]  R. Lenkinski,et al.  MR imaging of sodium in the human brain with a fast three-dimensional gradient-recalled-echo sequence at 4 T. , 2003, Academic radiology.

[7]  Peter Börnert,et al.  Three‐dimensional radial ultrashort echo‐time imaging with T2 adapted sampling , 2006, Magnetic resonance in medicine.

[8]  Ian C. Atkinson,et al.  Feasibility of mapping the tissue mass corrected bioscale of cerebral metabolic rate of oxygen consumption using 17-oxygen and 23-sodium MR imaging in a human brain at 9.4T , 2010, NeuroImage.

[9]  Keith R Thulborn,et al.  Safety of human MRI at static fields above the FDA 8T guideline: Sodium imaging at 9.4T does not affect vital signs or cognitive ability , 2007, Journal of magnetic resonance imaging : JMRI.

[10]  W. Perman,et al.  Regional T2 and Sodium Concentration Estimates in the Normal Human Brain by Sodium‐23 MR Imaging at 1.5 T , 1989, Journal of computer assisted tomography.

[11]  V Andrew Stenger,et al.  Parallel imaging with 3D TPI trajectory: SNR and acceleration benefits. , 2009, Magnetic resonance imaging.

[12]  A. Macovski,et al.  Selection of a convolution function for Fourier inversion using gridding [computerised tomography application]. , 1991, IEEE transactions on medical imaging.

[13]  Keith R Thulborn,et al.  Vital signs and cognitive function are not affected by 23‐sodium and 17‐oxygen magnetic resonance imaging of the human brain at 9.4 T , 2010, Journal of magnetic resonance imaging : JMRI.

[14]  Richard E. Blahut,et al.  Theory of Remote Image Formation , 2004 .

[15]  W. Rooney,et al.  A comprehensive approach to the analysis and interpretation of the resonances of spins 3/2 from living systems , 1991, NMR in biomedicine.

[16]  F E Boada,et al.  Fast three dimensional sodium imaging , 1997, Magnetic resonance in medicine.

[17]  Lawrence J. Berliner,et al.  Ultra High Field Magnetic Resonance Imaging , 2006 .

[18]  G H Glover,et al.  Methodology of in vivo human sodium MR imaging at 1.5 T. , 1986, Radiology.

[19]  K. Thulborn,et al.  Metabolic Magnetic Resonance Imaging: A Case for Bioscales in Medicine , 2011 .

[20]  Paul S. Hubbard,et al.  Nonexponential Nuclear Magnetic Relaxation by Quadrupole Interactions , 1970 .

[21]  Dwight G Nishimura,et al.  Design and analysis of a practical 3D cones trajectory , 2006, Magnetic resonance in medicine.

[22]  K R Thulborn,et al.  Comprehensive MR imaging protocol for stroke management: tissue sodium concentration as a measure of tissue viability in nonhuman primate studies and in clinical studies. , 1999, Radiology.

[23]  K. Thulborn,et al.  Characterization and correction of system delays and eddy currents for MR imaging with ultrashort echo‐time and time‐varying gradients , 2009, Magnetic resonance in medicine.

[24]  Wilson Fong Handbook of MRI Pulse Sequences , 2005 .

[25]  Paul A Bottomley,et al.  Tissue sodium concentration in human brain tumors as measured with 23Na MR imaging. , 2003, Radiology.

[26]  Aiming Lu,et al.  Quantitative sodium imaging with a flexible twisted projection pulse sequence , 2010, Magnetic resonance in medicine.

[27]  J. Ra,et al.  In Vivo NMR Imaging of Sodium‐23 in the Human Head , 1985, Journal of computer assisted tomography.

[28]  K. Thulborn,et al.  Sodium Magnetic Resonance Imaging and its Bioscale of Tissue Sodium Concentration , 2010 .

[29]  Aiming Lu,et al.  Quantitative sodium MR imaging and sodium bioscales for the management of brain tumors. , 2009, Neuroimaging clinics of North America.