Multi-echo RF spatial phase encoding for gradient-free imaging in a nonuniform B0-field at low-field

The cost and complexity of MR scanners can be significantly reduced by eliminating conventional linear gradient coils, and instead using RF coils for spatial encoding. Here we have developed a novel multi-echo RF phase encoding pulse sequence that exploits the Bloch-Siegert shift for nonlinear spatial encoding in a nonuniform, field-cycling, low-field MR system. Phantoms of varying sizes were successfully imaged using this pulse sequence, demonstrating that this technique can be used to perform gradient-free imaging in an inhomogeneous B0-field at low-field.