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Z-Spectrum analysis provides proton environment data (ZAPPED): a new two-pool technique for human gray and white matter.

Miyazaki M, Ouyang C, Zhou X, Murdoch JB, Fushimi Y, Okada T, Fujimoto K, Kido A, Arakawa Y, Miyamoto S, Togashi K - PLoS ONE (2015)

Bottom Line: The mean restricted exchangeable proton fraction, Fr, was found to be 0.17 in gray matter (GM) and 0.28 in white matter (WM) in healthy subjects.The percentages of Ff and Fr in GM are similar for all ages, whereas Fr shows a tendency to decrease with age in WM among healthy subjects.The ZAPPED method provides a simple phenomenological approach to estimating fractions and apparent T2 values of free and restricted MT-active protons, and it may offer clinical useful information.

View Article: PubMed Central - PubMed

Affiliation: MR Research, Toshiba Medical Research Institute, Vernon Hills, Illinois, United States of America.

ABSTRACT
A new technique - Z-spectrum Analysis Provides Proton Environment Data (ZAPPED) - was used to map cross-relaxing free and restricted protons in nine healthy subjects plus two brain tumor patients at 3T. First, MT data were acquired over a wide symmetric range of frequency offsets, and then a trio of quantitative biomarkers, i.e., the apparent spin-spin relaxation times (T2,f, T2,r) in both free and restricted proton pools as well as the restricted pool fraction Fr, were mapped by fitting the measured Z-spectra to a simple two-Lorentzian compartment model on a voxel-by-voxel basis. The mean restricted exchangeable proton fraction, Fr, was found to be 0.17 in gray matter (GM) and 0.28 in white matter (WM) in healthy subjects. Corresponding mean values for apparent spin-spin relaxation times were 785 µs (T2,f) and 17.7 µs (T2,r) in GM, 672 µs (T2,f) and 23.4 µs (T2,r) in WM. The percentages of Ff and Fr in GM are similar for all ages, whereas Fr shows a tendency to decrease with age in WM among healthy subjects. The patient ZAPPED images show higher contrast between tumor and normal tissues than traditional T2-weighted and T1-weighted images. The ZAPPED method provides a simple phenomenological approach to estimating fractions and apparent T2 values of free and restricted MT-active protons, and it may offer clinical useful information.

No MeSH data available.


Related in: MedlinePlus

Measured Z-spectra (red) of GM (left) and WM (right), and fitted curves (blue) on a logarithmic scale.The model assumes that there are two exchangeable proton components: restricted (green) and free (black).
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pone.0119915.g001: Measured Z-spectra (red) of GM (left) and WM (right), and fitted curves (blue) on a logarithmic scale.The model assumes that there are two exchangeable proton components: restricted (green) and free (black).

Mentions: Gray matter, white matter, and CSF were successfully segmented for all nine subjects. The measured mean signals of GM and WM for each subject were fitted with Lorentzian lineshapes, and the fitted Z-spectra matched the experimental ones very well. Fig. 1 shows an example of the curve-fitting of the free and restricted exchangeable components in GM (left) and WM (right) on a logarithmic frequency scale from one volunteer. The red curve represents the acquired Z-spectrum, and the blue one is the fitted Z-spectrum using the dual-Lorentzian model. The fitted free and restricted exchangeable components are shown separately in black and green. The normalized-root-mean-square difference (NRMSD) was 0.02 for the GM fit and 0.03 for the WM fit.


Z-Spectrum analysis provides proton environment data (ZAPPED): a new two-pool technique for human gray and white matter.

Miyazaki M, Ouyang C, Zhou X, Murdoch JB, Fushimi Y, Okada T, Fujimoto K, Kido A, Arakawa Y, Miyamoto S, Togashi K - PLoS ONE (2015)

Measured Z-spectra (red) of GM (left) and WM (right), and fitted curves (blue) on a logarithmic scale.The model assumes that there are two exchangeable proton components: restricted (green) and free (black).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358893&req=5

pone.0119915.g001: Measured Z-spectra (red) of GM (left) and WM (right), and fitted curves (blue) on a logarithmic scale.The model assumes that there are two exchangeable proton components: restricted (green) and free (black).
Mentions: Gray matter, white matter, and CSF were successfully segmented for all nine subjects. The measured mean signals of GM and WM for each subject were fitted with Lorentzian lineshapes, and the fitted Z-spectra matched the experimental ones very well. Fig. 1 shows an example of the curve-fitting of the free and restricted exchangeable components in GM (left) and WM (right) on a logarithmic frequency scale from one volunteer. The red curve represents the acquired Z-spectrum, and the blue one is the fitted Z-spectrum using the dual-Lorentzian model. The fitted free and restricted exchangeable components are shown separately in black and green. The normalized-root-mean-square difference (NRMSD) was 0.02 for the GM fit and 0.03 for the WM fit.

Bottom Line: The mean restricted exchangeable proton fraction, Fr, was found to be 0.17 in gray matter (GM) and 0.28 in white matter (WM) in healthy subjects.The percentages of Ff and Fr in GM are similar for all ages, whereas Fr shows a tendency to decrease with age in WM among healthy subjects.The ZAPPED method provides a simple phenomenological approach to estimating fractions and apparent T2 values of free and restricted MT-active protons, and it may offer clinical useful information.

View Article: PubMed Central - PubMed

Affiliation: MR Research, Toshiba Medical Research Institute, Vernon Hills, Illinois, United States of America.

ABSTRACT
A new technique - Z-spectrum Analysis Provides Proton Environment Data (ZAPPED) - was used to map cross-relaxing free and restricted protons in nine healthy subjects plus two brain tumor patients at 3T. First, MT data were acquired over a wide symmetric range of frequency offsets, and then a trio of quantitative biomarkers, i.e., the apparent spin-spin relaxation times (T2,f, T2,r) in both free and restricted proton pools as well as the restricted pool fraction Fr, were mapped by fitting the measured Z-spectra to a simple two-Lorentzian compartment model on a voxel-by-voxel basis. The mean restricted exchangeable proton fraction, Fr, was found to be 0.17 in gray matter (GM) and 0.28 in white matter (WM) in healthy subjects. Corresponding mean values for apparent spin-spin relaxation times were 785 µs (T2,f) and 17.7 µs (T2,r) in GM, 672 µs (T2,f) and 23.4 µs (T2,r) in WM. The percentages of Ff and Fr in GM are similar for all ages, whereas Fr shows a tendency to decrease with age in WM among healthy subjects. The patient ZAPPED images show higher contrast between tumor and normal tissues than traditional T2-weighted and T1-weighted images. The ZAPPED method provides a simple phenomenological approach to estimating fractions and apparent T2 values of free and restricted MT-active protons, and it may offer clinical useful information.

No MeSH data available.


Related in: MedlinePlus