Format

Send to

Choose Destination
Magn Reson Med. 2018 Aug;80(2):726-735. doi: 10.1002/mrm.27037. Epub 2017 Dec 1.

In vivo characterization of brain ultrashort-T2 components.

Author information

1
Department of Physics, Ecole Normale Supérieure de Cachan, Cachan, France.
2
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, USA.
3
UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, California, USA.
4
Department of Neurology, University of California, San Francisco, San Francisco, California, USA.

Abstract

PURPOSE:

Recent nuclear magnetic resonance and MRI studies have measured a fast-relaxing signal component with T2∗<1 ms in white matter and myelin extracts. In ex vivo studies, evidence suggests that a large fraction of this component directly arises from bound protons in the myelin phospholipid membranes. Based on these results, this ultrashort-T2 component in nervous tissue is a new potential imaging biomarker of myelination, which plays a critical role in neuronal signal conduction across the brain and loss or degradation of myelin is a key feature of many neurological disorders. The goal of this work was to characterize the relaxation times and frequency shifts of ultrashort-T2 components in the human brain.

METHODS:

This required development of an ultrashort echo time relaxometry acquisition strategy and fitting procedure for robust measurements in the presence of ultrashort T2∗ relaxation times and large frequency shifts.

RESULTS:

We measured an ultrashort-T2 component in healthy volunteers with a median T2∗ between 0.5-0.7 ms at 3T and 0.2-0.3 ms at 7T as well as an approximately -3 ppm frequency shift from water.

CONCLUSION:

To our knowledge, this is the first time a chemical shift of the ultrashort-T2 brain component has been measured in vivo. This chemical shift, at around 1.7 ppm, is similar to the primary resonance of most lipids, indicating that much of the ultrashort-T2 component observed in vivo arises from bound protons in the myelin phospholipid membranes. Magn Reson Med 80:726-735, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

KEYWORDS:

myelin imaging; myelin membranes; relaxometry; ultrashort echo time MRI; ultrashort-T2

PMID:
29194734
PMCID:
PMC5910201
[Available on 2019-08-01]
DOI:
10.1002/mrm.27037

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center