MULTI-ECHO WATER-FAT SEPARATION

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Purpose: This project aims to enable fast and efficient scanning with robust water-fat separation using multi-echo sequences. To achieve this aim, requires a combination of robust field-map estimation and imaging techniques that work with novel multi-echo sequences. Methods: We have developed a multi-resolution field map estimation method that directly locates possible field map values at a coarse resolution and then progressively refines field map estimation to full resolution. To improve imaging efficiency and reduce motion induced artifacts, we have implemented a bipolar multi-echo sequence that acquires images at different echo times using alternating readout gradients to maximize scan efficiency. For practical use, the problems caused by the alternating readout gradients, including k-space echo misalignment, field-inhomogeneity induced misregistration, and chemical-shift induced misregistration must be addressed. Summary: The developed techniques and sequences offer many advantages such as high SNR efficiency, reduced echo-spacing compared to standard multi-echo sequences, reduced motion induced artifacts, and reliable field-map estimation and water-fat separation.