Dualband spectral-spatial RF pulses for prostate MR spectroscopic imaging

Although MR spectroscopic imaging (MRSI) of the prostate has demonstrated c linical utility for the staging and monitoring of cancer extent, current ac quisition methods are often inadequate in several aspects. Conventional 180 degrees pulses can suffer from chemical shift misregistration, and have hi gh peak-power requirements that can exceed hardware limits in many prostate MRSI studies. Optimal water and lipid suppression are also critical to obt ain interpretable spectra. While complete suppression of the periprostatic lipid resonance is desired, controlled partial suppression of water can pro vide a valuable phase and frequency reference for data analysis and an asse ssment of experimental success in cases in which all other resonances are u ndetectable following treatment. In this study, new spectral-spatial RIF pu lses were developed to negate chemical shift misregistration errors and to provide dualband excitation with partial excitation of the water resonance and full excitation of the metabolites of interest. Optimal phase modulatio n was also included in the pulse design to provide 40% reduction in peak RF power. Patient studies using the new pulses demonstrated both feasibility and clear benefits in the reliability and applicability of prostate cancer MRSI. (C) 2001 Wiley-Liss, Inc.