Fat suppression with an improved selective presaturation pulse

Chemical shift selective (CHESS) imaging is an efficient and easily implemented technique for suppression of the fat component in clinical images. A Gaussian pulse is widely used as the selective presaturation pulse in the CHESS technique. However, a Gaussian pulse hardly performs well even if the magnetic field is very carefully shimmed. In clinical applications, the fat and water peaks are always inhomogeneously broadened. We have analyzed the performance of the Gaussian pulse in the presence of magnetic field inhomogeneities and present a more efficient selective presaturation pulse developed by applying the conjugate gradient method. The resulting pulse performs well without any requirement for magnetic field homogeneity greater than needed for routine diagnostic MR imaging.