Z-Spectrum Analysis Provides Proton Environment Data (ZAPPED): A New Two-Pool Technique for Human Gray and White Matter

• Published in: PloS one Vol. 10; no. 3; p. e0119915
• Main Authors: Miyazaki, Mitsue, Ouyang, Cheng, Zhou, Xiangzhi, Murdoch, James B., Fushimi, Yasutaka, Okada, Tomohisa, Fujimoto, Koji, Kido, Aki, Arakawa, Yoshiki, Miyamoto, Susumu, Togashi, Kaori
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.03.2015; Public Library of Science (PLoS)
• Subjects: Adult; Age; Aged; Aging; Biomarkers; Brain; Brain cancer; Brain Mapping - methods; Brain Neoplasms - diagnosis; Brain Neoplasms - pathology; Brain research; Brain tumors; Case-Control Studies; Data acquisition; Female; Glioma; Gray Matter - cytology; Gray Matter - pathology; Human subjects; Humans; Image contrast; Image Processing, Computer-Assisted; Magnetic Resonance Imaging - methods; Male; Mathematical programming; Medical research; Middle Aged; Neurosurgery; NMR; Nuclear magnetic resonance; Nuclear medicine; Offsets; Protons; Spectrum analysis; Studies; Substantia alba; Substantia grisea; Tissues; White Matter - cytology; White Matter - pathology; United States > US; Illinois; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0119915

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.