Jimin Ren1,2, A Dean Sherry1,2,3, Craig R Malloy1,2,4,5. 1. Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390. 2. Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390. 3. Department of Chemistry, University of Texas at Dallas, Richardson, TX, 75080. 4. Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390. 5. VA North Texas Health Care System, Dallas, TX, 75216.
Abstract
PURPOSE: To develop an improved method to measure the 31 P nuclear Overhauser effect (NOE) for evaluation of adenosine triphosphate (ATP) dynamics in terms of correlation time (τc ), and contribution of dipole-dipole (DD) and chemical shift anisotropy (CSA) mechanisms to T1 relaxation of ATP in human brain. METHODS: The NOE of ATP in human brain was evaluated by monitoring changes in magnetization in the β-ATP signal following a band inversion of all downfield 31 P resonances. The magnetization changes observed were analyzed using the Bloch-McConnell-Solomon formulation to evaluate the relaxation and motion dynamic parameters that describe interactions of ATP with cellular solids in human brain tissue. RESULTS: The maximal transient NOE, observed as a reduction in the β-ATP signal, was 24 ± 2% upon band inversion of γ- and α-ATP, which is 2-3-fold higher than achievable by frequency-selective inversion of either γ- or α-ATP. The rate of 31 P-31 P cross relaxation (0.21 ± 0.02 s-1 ) led to a τc value of (9.1 ± 0.8) × 10-8 s for ATP in human brain. The T1 relaxation of β-ATP is dominated by CSA over the DD mechanism (60%: 40%). CONCLUSIONS: The band inversion method proved effective in amplifying 31 P NOE, and thus facilitating ATP τc and relaxation measurements. This technique renders ATP a potentially useful reporter molecule for cellular environments. Magn Reson Med 77:1409-1418, 2017.
PURPOSE: To develop an improved method to measure the 31 P nuclear Overhauser effect (NOE) for evaluation of adenosine triphosphate (ATP) dynamics in terms of correlation time (τc ), and contribution of dipole-dipole (DD) and chemical shift anisotropy (CSA) mechanisms to T1 relaxation of ATP in human brain. METHODS: The NOE of ATP in human brain was evaluated by monitoring changes in magnetization in the β-ATP signal following a band inversion of all downfield 31 P resonances. The magnetization changes observed were analyzed using the Bloch-McConnell-Solomon formulation to evaluate the relaxation and motion dynamic parameters that describe interactions of ATP with cellular solids in human brain tissue. RESULTS: The maximal transient NOE, observed as a reduction in the β-ATP signal, was 24 ± 2% upon band inversion of γ- and α-ATP, which is 2-3-fold higher than achievable by frequency-selective inversion of either γ- or α-ATP. The rate of 31 P-31 P cross relaxation (0.21 ± 0.02 s-1 ) led to a τc value of (9.1 ± 0.8) × 10-8 s for ATP in human brain. The T1 relaxation of β-ATP is dominated by CSA over the DD mechanism (60%: 40%). CONCLUSIONS: The band inversion method proved effective in amplifying 31 P NOE, and thus facilitating ATP τc and relaxation measurements. This technique renders ATP a potentially useful reporter molecule for cellular environments. Magn Reson Med 77:1409-1418, 2017.
Authors: Hye-Young Heo; Craig K Jones; Jun Hua; Nirbhay Yadav; Shruti Agarwal; Jinyuan Zhou; Peter C M van Zijl; Jay J Pillai Journal: J Magn Reson Imaging Date: 2015-12-10 Impact factor: 4.813