In vivo measurement of a new source of contrast, the dipolar relaxation time, T1D, using a modified inhomogeneous magnetization transfer (ihMT) sequence. Issue 4 (17th November 2016)

• Record Type: Journal Article
• Authors: Varma, Gopal; Girard, Olivier M.; Prevost, Valentin H.; Grant, Aaron K.; Duhamel, Guillaume; Alsop, David C.
• Is Part Of: Magnetic resonance in medicine. Volume 78:Issue 4(2017)
• Page Start: 1362
• Page End: 1372
• Publication Date: 2016-11-17
• Subjects: dipolar relaxation -- ihMT -- inhomogeneous magnetization transfer -- MT -- myelin -- quantitative magnetization transfer; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.26523
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: This paper describes a technique that can be used in vivo to measure the dipolar relaxation time, T 1 D, of macromolecular protons contributing to magnetization transfer (MT) in tissues and to produce quantitative T 1 D maps. Theory and Methods: The technique builds upon the inhomogeneous MT (ihMT) technique that is particularly sensitive to tissue components with long T 1 D . 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 T 1 D = (5.9 ± 1.2) ms in gray matter and T 1 D = (6.2 ± 0.4) ms in white matter regions and provided maps of the T 1 D parameter. Conclusion: The model and experiments described provide access to a new relaxation characteristic of tissue with potentially unique diagnostic information. Magn Reson Med 78:1362–1372, 2017. © 2016 International Society for Magnetic Resonance in Medicine.