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Evaluation of multi-channel phase reconstruction methods for quantitative susceptibility mapping on postmortem human
Fábio Seiji Otsuka1, Maria Concepcion Garcia Otaduy2, José Henrique Monteiro Azevedo1
1InBrain, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo USP, Ribeirão Preto, São Paulo, Brazil.
Quantitative Susceptibility Mapping (QSM) phase image reconstruction for multi-channel MRI requires reliable data. This study found that a phase combination method with a weighting factor k=1 generally outperforms other methods for brain iron studies.
Area of Science:
- Neuroimaging
- Quantitative Susceptibility Mapping (QSM)
- Magnetic Resonance Imaging (MRI)
Background:
- Quantitative Susceptibility Mapping (QSM) is crucial for brain iron quantification in neurodegenerative diseases.
- QSM relies on accurate phase image reconstruction from multi-channel MRI data.
- Existing phase reconstruction methods require evaluation for optimal performance.
Purpose of the Study:
- To compare the performance of different phase reconstruction methods for multi-channel MRI.
- To identify the optimal weighting factor (k) for phase combination methods in QSM.
- To evaluate reconstruction techniques using simulated and postmortem brain datasets.
Main Methods:
- Compared phase matching algorithms (MCPC3D-S, VRC) and phase combination methods with varying magnitude weighting powers (k=0-4).
- Applied methods to a simulated 4-coil brain dataset and 22 postmortem subjects (32-channel coil at 7T).
- Evaluated Root Mean Squared Error (RMSE) for simulated data and calculated mean (MS) and standard deviation (SD) of susceptibility values for deep gray matter regions.
Main Results:
- Qualitative analysis showed no significant differences, except for artifacts with the Adaptive approach on postmortem data.
- For postmortem data, MS and SD were not statistically different between k=1 and k=2, though k=2 showed boundary artifacts.
- For simulated data, RMSE decreased near coils but increased centrally and overall with higher k values.
Conclusions:
- Alternative phase reconstruction methods are needed for multi-channel QSM without a reference scan.
- The phase combination method with k=1 is generally preferred over other powers of k for QSM reconstruction.
- Optimal reconstruction balances accuracy across different brain regions and minimizes artifacts.
