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Updated: Jun 13, 2026
Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
Published on: December 18, 2016
Limitations of rapid myelin water quantification using 3D bSSFP
C Lenz1, M Klarhöfer, K Scheffler
1Division of Radiological Physics, University of Basel Hospital, Petersgraben 4, 4031, Basel, Switzerland. claudia.lenz@unibas.ch
Object:
Imaging of the myelin water fraction (MWF) is conventionally performed using a multi-echo spin-echo sequence. This technique requires long acquisition times and therefore often suffers from a lack of volume coverage. In this work, the application of 3D balanced steady-state free precession (bSSFP) sequences to extract high-resolution myelin water maps is discussed.
Materials And Methods:
Based on a two-pool water exchange model, an approximate bSSFP signal equation is derived and applied to fit the flip angle dependence of the in vivo bSSFP signal. Thereby, the MWF and signal amplitude are fitted, while a priori assumptions are made for the other parameters of the two-pool system.
Results:
The effects of magnetization transfer, finite RF pulses, B (0) and B (1) inhomogeneities, as well as variation of the constant fit parameters, are investigated. Acquisition and calculation of quantitative, high-resolution MWF maps from white matter of healthy volunteers based on bSSFP is feasible and averaged MWF fit results agree with literature. However, results from numerical simulations indicate a severe dependence of the derived MWF values on the constant two-pool parameters.
Conclusion:
The demonstrated dependence of the MWF on the two-pool parameters considerably impairs the applicability of the proposed method.
Insights
This study explored using 3D balanced steady-state free precession (bSSFP) for myelin water fraction (MWF) mapping. While feasible, the method
Area of Science:
- Neuroimaging
- Magnetic Resonance Imaging (MRI)
- Biophysics
Background:
- Conventional myelin water fraction (MWF) imaging uses multi-echo spin-echo sequences, which have long acquisition times and limited volume coverage.
- Developing faster MRI techniques for accurate MWF quantification is crucial for neurological research.
Purpose of the Study:
- To investigate the feasibility of using 3D balanced steady-state free precession (bSSFP) sequences for high-resolution myelin water mapping.
- To assess the potential of bSSFP as an alternative to conventional MWF imaging methods.
Main Methods:
- Derived an approximate bSSFP signal equation based on a two-pool water exchange model.
- Fitted the flip angle dependence of in vivo bSSFP signals to determine MWF and signal amplitude, making assumptions for other parameters.
- Investigated the influence of factors like magnetization transfer and field inhomogeneities on MWF values.
Main Results:
- Acquisition and calculation of quantitative, high-resolution MWF maps from healthy volunteers using bSSFP were demonstrated as feasible.
- Averaged MWF results obtained with bSSFP showed agreement with existing literature values.
- Numerical simulations revealed a significant dependency of derived MWF values on the assumed two-pool model parameters.
Conclusions:
- The proposed bSSFP method for MWF mapping is feasible but requires careful consideration of underlying model parameters.
- The dependence of MWF on two-pool parameters significantly limits the current applicability of this bSSFP-based approach.
