Correction of B1-inhomogeneities for relaxation-compensated CEST imaging at 7 T.

摘要: Chemical exchange saturation transfer (CEST) imaging of endogenous agents in vivo is influenced by direct water proton (spillover) and semi-solid macromolecular magnetization (MT). Lorentzian fit isolation application the inverse metric yields pure CEST contrast AREX, which less affected these processes, but still depends on measurement technique, particular irradiation amplitude B1 pulses. This study focuses two well-known effects slow regime originating from amide aliphatic protons resonating at 3.5 ppm or −3.5 ppm protons, respectively. A B1-correction contrasts crucial for evaluation data obtained clinical studies high field strengths with strong B1-inhomogeneities. Herein approaches B1-inhomogeneity correction, based either Z-spectra, are investigated. Both rely multiple acquisitions different B1-values. One volunteer was examined eight B1-values to optimize strength correction algorithm. Histogram allowed quantification quality B1-correction. Finally, applied images a patient oligodendroglioma WHO grade 2, showed improvement image compared non-corrected images, especially tumor region. Copyright © 2015 John Wiley & Sons, Ltd.