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Magn Reson Med. 2018 May;79(5):2795-2803. doi: 10.1002/mrm.26946. Epub 2017 Oct 11.

MEDI+0: Morphology enabled dipole inversion with automatic uniform cerebrospinal fluid zero reference for quantitative susceptibility mapping.

Author information

1
Department of Radiology, Weill Cornell Medical College, New York, New York, USA.
2
Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
3
Department of Radiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.

Abstract

PURPOSE:

To develop a quantitative susceptibility mapping (QSM) method with a consistent zero reference using minimal variation in cerebrospinal fluid (CSF) susceptibility.

THEORY AND METHODS:

The ventricular CSF was automatically segmented on the R2* map. An L2 -regularization was used to enforce CSF susceptibility homogeneity within the segmented region, with the averaged CSF susceptibility as the zero reference. This regularization for CSF homogeneity was added to the model used in a prior QSM method (morphology enabled dipole inversion [MEDI]). Therefore, the proposed method was referred to as MEDI+0 and compared with MEDI in a numerical simulation, in multiple sclerosis (MS) lesions, and in a reproducibility study in healthy subjects.

RESULTS:

In both the numerical simulations and in vivo experiments, MEDI+0 not only decreased the susceptibility variation within the ventricular CSF, but also suppressed the artifact near the lateral ventricles. In the simulation, MEDI+0 also provided more accurate quantification compared to MEDI in the globus pallidus, substantia nigra, corpus callosum, and internal capsule. MEDI+0 measurements of MS lesion susceptibility were in good agreement with those obtained by MEDI. Finally, both MEDI+0 and MEDI showed good and similar intrasubject reproducibility.

CONCLUSION:

QSM with a minimal variation in ventricular CSF is viable to provide a consistent zero reference while improving image quality. Magn Reson Med 79:2795-2803, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

KEYWORDS:

CSF homogeneity; QSM; zero reference

PMID:
29023982
PMCID:
PMC5821583
DOI:
10.1002/mrm.26946
[Indexed for MEDLINE]
Free PMC Article

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