title: Slice-selective broadband refocusing pulses for the robust generation of crushed spin-echoes.
abstract: A major challenge for in vivo magnetic resonance spectroscopy with point-resolved spectroscopy (PRESS) is the low signal intensity for the measurement of weakly scalar coupled spins, for example lactate. The chemical-shift displacement error between the two coupling partners of the lactate molecule leads to a signal decrease. The chemical-shift displacement error is decreased and therefore the lactate signal is increased by using refocusing pulses with a broad bandwidth. Previously, slice-selective broadband universal rotation pulses (S-BURBOP) were designed and applied as refocusing pulses in the PRESS pulse sequence (Janich MA, et al., Journal of Magnetic Resonance, 2011, 213, 126-135). However, S-BURBOP pulses leave a phase error across the slice which is superimposed on the spectra when spatially resolving the PRESS voxel. In the present novel design of slice-selective broadband refocusing pulses (S-BREBOP) this phase error is avoided. S-BREBOP pulses obtain 2.5 times the bandwidth of conventional Shinnar-Le Roux pulses and are robust against ±20% miscalibration of the B(1) amplitude. S-BREBOP pulses were validated in phantoms and in a low-grade brain tumor of a patient. Compared to conventional Shinnar-Le Roux pulses they lead to a decrease of the chemical-shift displacement error and consequently a lactate signal increase.
authors.affiliation: Technische Universität München, Department of Chemistry, Munich, Germany. martin.janich@ge.com
authors.forename: Martin A
authors.initials: MA
authors.lastname: Janich
authors.forename: Mary A
authors.initials: MA
authors.lastname: McLean
authors.forename: Ralph
authors.initials: R
authors.lastname: Noeske
authors.forename: Steffen J
authors.initials: SJ
authors.lastname: Glaser
authors.forename: Rolf F
authors.initials: RF
authors.lastname: Schulte
mesh_terms: D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology; D002138:Calibration; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006801:Humans; D007773:Lactates / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D009837:Oligodendroglioma / Q000378:metabolism / Q000473:pathology; D013113:Spin Labels
chemical_list: D007773:Lactates; D013113:Spin Labels