Optimization of CEST saturation parameters at 1.5T for brain tumor imaging

Motivation: 1.5T CEST is more challenging to recognize tumor regions compared to 3T due to reduced signal-to-noise ratio (SNR) and a coarser spectral resolution. Goal(s): Optimize CEST saturation to maximize the tumor-cNAWM contrast. Approach: Seven-pool Bloch-McConnell equation were utilized to fit 1.5T and 3T CEST data of health volunteers. Parameters were then fine-tuned to match cNAWM and tumor data. Fitted parameters were utilized in simulation under different saturation parameters to maximize tumor-cNAWM contrast. Results: Ten 100ms Gaussian pulses, 95% DC and 1 μT B1 are optimized to generate maximum tumor-cNAWM contrast at 1.5T, subject to practical acquisition time and hardware constraints. Impact: Our optimized CEST saturation parameters maximizes tumor contrast at 1.5T, facilitating the applicability of CEST MRI with reduced SNR and a coarser spectral resolution at 1.5T.