title: Balanced Steady-State Free Precession (bSSFP) from an effective field perspective: Application to the detection of chemical exchange (bSSFPX).
abstract: Chemical exchange saturation transfer (CEST) is a novel contrast mechanism and it is gaining increasing popularity as many promising applications have been proposed and investigated. Fast and quantitative CEST imaging techniques are further needed in order to increase the applicability of CEST for clinical use as well as to derive quantitative physiological and biological information. Steady-state methods for fast CEST imaging have been reported recently. Here, we observe that an extreme case of these methods is a balanced steady-state free precession (bSSFP) sequence. The bSSFP in itself is sensitive to the exchange processes; hence, no additional saturation or preparation is needed for CEST-like data acquisition. The bSSFP experiment can be regarded as observation during saturation, without separate saturation and acquisition modules as used in standard CEST and similar experiments. One of the differences from standard CEST methods is that the bSSFP spectrum is an XY-spectrum not a Z-spectrum. As the first proof-of-principle step, we have implemented the steady-state bSSFP sequence for chemical exchange detection (bSSFPX) and verified its feasibility in phantom studies. These studies have shown that bSSFPX can achieve exchange-mediated contrast comparable to the standard CEST experiment. Therefore, the bSSFPX method has a potential for fast and quantitative CEST data acquisition.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Division of MR Research, Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Grant
authors.affiliation: Philips Research, Hamburg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Keupp
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Lenkinski
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA. Electronic address: Elena.Vinogradov@UTSouthwestern.edu.
authors.forename: Elena
authors.initials: E
authors.lastname: Vinogradov
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio
keywords: CEST; Spin-lock; Steady-state; T(1ρ); bSSFP