Get access

Quantitative characterization of nuclear overhauser enhancement and amide proton transfer effects in the human brain at 7 tesla

Authors

  • Dapeng Liu,

    1. State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
    2. UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing, China and Los Angeles, California, USA
    3. Graduate University, Chinese Academy of Sciences, Beijing, China
    Search for more papers by this author
  • Jinyuan Zhou,

    1. Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
    2. F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
    Search for more papers by this author
  • Rong Xue,

    Corresponding author
    1. State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
    2. UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing, China and Los Angeles, California, USA
    • State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, People's Republic of China. E-mail: rxue@bcslab.ibp.ac.cn

    Search for more papers by this author
  • Zhentao Zuo,

    1. State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
    2. UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing, China and Los Angeles, California, USA
    Search for more papers by this author
  • Jing An,

    1. Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China
    Search for more papers by this author
  • Danny J. J. Wang

    1. UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing, China and Los Angeles, California, USA
    2. Department of Neurology, UCLA, Los Angeles, California, USA
    Search for more papers by this author

Abstract

Purpose

This study aimed to quantitatively investigate two main magnetization transfer effects at low B1: the nuclear Overhauser enhancement (NOE) and amide proton transfer in the human brain at 7 T.

Methods

The magnetization transfer effects in the human brain were characterized using a four-pool proton model, which consisted of bulk water, macromolecules, an amide group of mobile proteins and peptides, and NOE-related protons resonating upfield. The pool sizes, exchange rates, and relaxation times of these proton pools were investigated quantitatively by fitting, and the net signals of amide proton transfer and NOE were simulated based on the fitted parameters.

Results

The results showed that the four-pool model fitted the experimental data quite well, and the NOE effects in human brain at 7 T had a broad spectrum distribution. The NOE effects peaked at a B1 of ∼ 1–1.4 μT and were significantly stronger in the white matter than in the gray matter, corresponding to a pool-size ratio ∼ 2:1. As the amide proton transfer effect was relatively small compared with the NOE effects, magnetization transfer asymmetry analysis yielded an NOE-dominated contrast in the healthy human brain in this range of B1.

Conclusion

These findings are important to identify the source of NOE effects and to quantify amide proton transfer effects in human brain at 7 T. Magn Reson Med, 70:1070–1081, 2013. © 2012 Wiley Periodicals, Inc.

Get access to the full text of this article

Ancillary