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Magn Reson Med. 2016 May;75(5):2100-6. doi: 10.1002/mrm.25811. Epub 2015 Jun 22.

Time-efficient, high-resolution, whole brain three-dimensional macromolecular proton fraction mapping.

Author information

1
Department of Radiology, University of Washington, Seattle, Washington, USA.
2
Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation.

Abstract

PURPOSE:

Macromolecular proton fraction (MPF) mapping is a quantitative MRI method that reconstructs parametric maps of a relative amount of macromolecular protons causing the magnetization transfer (MT) effect and provides a biomarker of myelination in neural tissues. This study aimed to develop a high-resolution whole brain MPF mapping technique using a minimal number of source images for scan time reduction.

METHODS:

The described technique was based on replacement of an actually acquired reference image without MT saturation by a synthetic one reconstructed from R1 and proton density maps, thus requiring only three source images. This approach enabled whole brain three-dimensional MPF mapping with isotropic 1.25 × 1.25 × 1.25 mm(3) voxel size and a scan time of 20 min. The synthetic reference method was validated against standard MPF mapping with acquired reference images based on data from eight healthy subjects.

RESULTS:

Mean MPF values in segmented white and gray matter appeared in close agreement with no significant bias and small within-subject coefficients of variation (<2%). High-resolution MPF maps demonstrated sharp white-gray matter contrast and clear visualization of anatomical details, including gray matter structures with high iron content.

CONCLUSIONS:

The proposed synthetic reference method improves resolution of MPF mapping and combines accurate MPF measurements with unique neuroanatomical contrast features.

KEYWORDS:

gray matter; macromolecular proton fraction; magnetic resonance imaging; magnetization transfer; myelin; white matter

PMID:
26102097
PMCID:
PMC4688249
DOI:
10.1002/mrm.25811
[Indexed for MEDLINE]
Free PMC Article

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