B1 Correction of MRSI Data Using Unsuppressed Water Signals

Motivation: B1 inhomogeneities hinders biological interpretation of MRSI results. By correcting B1 effects, quantitative estimation of metabolite concentrations can be obtained from MRSI data. Goal(s): To develop a practical method for B1-correction of MRSI using the companion unsuppressed water signals. Approach: We used a non-water-suppressed MRSI data acquisition scheme with variable-flip-angle frames to encode B1 information. B1 effects were estimated with physics-based and data-driven priors and corrected from metabolite maps, producing quantitative concentration estimations. Results: Results from phantom, healthy subjects and tumor patients demonstrated the feasibility of B1-corrected quantitative MRSI. Metabolite concentrations obtained from the proposed method aligned with the ground truth and literature. Impact: The proposed method enables quantitative metabolite concentration estimation, which is robust even in pathological tissues. This method is expected to enhance the accuracy, robustness and reproducibility of MRSI technologies.