Intrinsic Field Homogeneity Correction in Fast Spin Echo Based Amide Proton Transfer MRI

Jochen Keupp¹, Holger Eggers¹

Amide proton transfer (APT), a powerful technique for molecular imaging of endogenous proteins, is based on an asymmetry analysis of RF saturation frequency offsets acquired around the water resonance, which needs precise B₀ homogeneity correction. While fast spin-echo (FSE) based APT has superior contrast-to-noise ratio, the previously shown multi-echo APT acquisition with intrinsic Dixon-type B₀ mapping/correction is restricted to gradient-echo sequences. We propose a FSE-Dixon APT technique with varied echo time shifts, using iterative Dixon reconstruction across different positive saturation frequency offsets for intrinsic B₀ mapping and correction. Feasibility in the human head is demonstrated using a clinical 3T scanner.