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J Magn Reson Imaging. 2016 Feb;43(2):463-73. doi: 10.1002/jmri.24976. Epub 2015 Jun 14.

Magnetic susceptibility contrast variations in multiple sclerosis lesions.

Author information

1
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
2
Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
3
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
4
Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, Guangzhou, China.

Abstract

PURPOSE:

Recent magnetic resonance imaging (MRI) studies have revealed heterogeneous magnetic susceptibility contrasts in multiple sclerosis (MS) lesions. Due to its sensitivity to disease-related iron and myelin changes, magnetic susceptibility-based measures may better reflect some pathological features of MS lesions. Hence, we sought to characterize MS lesions using combined R2* mapping and quantitative susceptibility mapping (QSM).

MATERIALS AND METHODS:

In all, 306 MS lesions were selected from 24 MS patients who underwent 7T MRI. Maps of R2*, frequency, and quantitative susceptibility were calculated using acquired multiecho gradient echo (GRE) phase data. Lesions were categorized based on their image intensity or their anatomical locations. R2* and susceptibility values were quantified in each lesion based on manually drawn lesion masks and compared between lesion groups showing different contrast patterns. Correlations between R2* and susceptibility were also tested in these lesion groups.

RESULTS:

In 38% of selected lesions the frequency map did not show the same contrast pattern as the susceptibility map. While most lesions (93%) showed hypointensity on R2*, the susceptibility contrast in lesions varied, with 40% being isointense and 58% being hyperintense in the lesion core. Significant correlations (r = 0.31, P < 0.001) between R2* and susceptibility were found in susceptibility hyperintense lesions, but not in susceptibility isointense lesions. In addition, a higher proportion (74%) of periventricular lesions was found to be susceptibility hyperintense as compared to subcortical (53%) or juxtacortical (38%) lesions.

CONCLUSION:

Combining R2* and QSM is useful to characterize heterogeneity in MS lesions.

KEYWORDS:

R2*; iron; lesion; multiple sclerosis; myelin; quantitative susceptibility mapping (QSM)

PMID:
26073973
PMCID:
PMC4678033
DOI:
10.1002/jmri.24976
[Indexed for MEDLINE]
Free PMC Article

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