Two‐point B1 correction for CEST MRI by fusing voxel‐wise interpolation and T1W voxel‐clustering

Abstract Purpose As a sensitive metabolic MRI technique, CEST images are easily contaminated by inhomogeneity due to strong dependence on saturation . We aim to develop an efficient and robust two‐point ‐correction method. Methods The proposed method only acquires CEST images under two saturation 's, {, }, with desired in between. Besides, voxel‐wise Z‐ interpolation (branch A), we performed another Z‐‐ calibration (branch B), which divided image voxels into bins according to the image and fitted a Z‐ curve for each bin. To ensure each voxel adopts a better‐corrected value, we fused the images corrected from both branches, according to a mask predicted by a retrospectively trained model. For validation, glutamate CEST (GluCEST) experiments of phantom and healthy volunteers were acquired on a 5T scanner. A total of 14 pairs from 2.4μT to 3.6μT were evaluated, with the 7‐‐correction as gold standard. Results Across glutamate phantoms with three distinct layouts, branch B demonstrated reliable correction performance for 14 pairs, achieving a mean absolute error (MAE) of Z(3 ppm) ≤ 5% in all 42 experiments. For six healthy volunteers, branch B yielded Z(3 ppm) images that closely matched the 7‐ correction, and the MAE distributions proved robust to voxel‐binning, fitting strategies, and the choice of pair. After fusion, all volunteers displayed better structural similarity index measure (SSIM), than the lower ones corrected by either branch. Conclusions By only acquiring two , our ‐correction strategy proved comparable performance to multi‐ methods, exhibiting robustness to selection and slice positions.