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In vivo measurement of a new source of contrast, the dipolar relaxation time, T1D , using a modified inhomogeneous magnetization transfer (ihMT) sequence

Gopal Varma 1 Olivier M. Girard 2 Valentin H. Prevost 2 Aaron K. Grant 1 Guillaume Duhamel 2 David C. Alsop 1
1 Beth Israel Deaconess - Harvard Medical School
2 CRMBM - Centre de résonance magnétique biologique et médicale
Abstract : PURPOSE: This paper describes a technique that can be used in vivo to measure the dipolar relaxation time, T1D , of macromolecular protons contributing to magnetization transfer (MT) in tissues and to produce quantitative T1D maps. THEORY AND METHODS: The technique builds upon the inhomogeneous MT (ihMT) technique that is particularly sensitive to tissue components with long T1D . A standard ihMT experiment was altered to introduce a variable time for switching between positive and negative offset frequencies for RF saturation. A model for the dependence of ihMT was developed and used to fit data acquired in vivo. RESULTS: Application of the method to images from brains of healthy volunteers produced values of T1D  = (5.9 ± 1.2) ms in gray matter and T1D  = (6.2 ± 0.4) ms in white matter regions and provided maps of the T1D parameter. CONCLUSION: The model and experiments described provide access to a new relaxation characteristic of tissue with potentially unique diagnostic information. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
Keywords : myelin ihMT Inhomogeneous magnetization transfer MT crmbm Dipolar relaxation Quantitative magnetization transfer
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https://hal-amu.archives-ouvertes.fr/hal-01425505
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Submitted on : Tuesday, January 3, 2017 - 3:55:45 PM
Last modification on : Wednesday, August 19, 2020 - 12:08:19 PM

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Gopal Varma, Olivier M. Girard, Valentin H. Prevost, Aaron K. Grant, Guillaume Duhamel, et al.. In vivo measurement of a new source of contrast, the dipolar relaxation time, T1D , using a modified inhomogeneous magnetization transfer (ihMT) sequence. Magnetic Resonance in Medicine, Wiley, 2016, ⟨10.1002/mrm.26523⟩. ⟨hal-01425505⟩

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