Virtual Coil Concept for Improved Parallel MRI Employing Conjugate Symmetric Signals

A new approach for utilizing conjugate k-space symmetry for improved parallel MRI performance is presented. By generating virtual coils containing conjugate symmetric k-space signals from actual coils, additional image- and coil-phase information can be incorporated into the reconstruction process for parallel acquisition techniques. In that way the reconstruction condi-tions are improved, resulting in less noise enhancement. In particular in combination with generalized autocalibrating par-tially parallel acquisitions (GRAPPA), the virtual coil concept represents a practical approach since no explicit spatial phase information is required. In addition, the influence of phase vari-ations originating from the complex receiver coils as well as from the background is investigated. It is shown that there exist background phase distributions yielding an optimized pMR