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. Introduction: Fat suppression is crucial to numerous clinical applications of MRI, including cardiovascular, abdominal and musculoskeletal imaging. In previous work, partially supported by this research resource, investigators have developed a robust iterative reconstruction technique, IDEAL, to separate water from fat using several MR images with different echo times resulting in different phase difference between fat and water signals. Initial clinical evaluation of IDEAL has been successful. However, the technique can benefit from scan time reduction, and improved efficiency, which are both goals of the present work. Methods and Discussion: IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation) is a robust algorithm for separation of water and fat using images with at least 3 different echo times. Normally, a full acquisition is used for each echo time. In this work we use a multi-echo readout, that acquires data for all three echo times in a single acquisition. This reduces total scan time by about a factor of two, without reducing SNR significantly, and improves robustness to patient motion. We have applied this technique to musculoskeletal imaging to produce a sub-five-minute 3D cartilage imaging sequence, and to 3D liver imaging, which enables imaging within a breath-hold. Results show excellent fat/water separation in most cases, though as the echo spacing increases, there are cases where the fat/water swaps occur. Future work will involve improving the robustness of the reconstruction as the echo spacing increases, allowing higher resolution imaging. We will also apply this technique to rapid cardiac imaging, where motion makes the standard IDEAL technique difficult.
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