title: Off-resonance proton T1rho dispersion imaging of 17O-enriched tissue phantoms.
abstract: Proton T1rho dispersion imaging is a recently described method for indirect detection of 17O. However, clinical implementation of this technique is hindered by the requirement for a high-amplitude spin-locking field (gammaB1 > 1 kHz) that exceeds current limitations in specific absorption rate (SAR). Here, a strategy is offered for circumventing high SAR in T1rho dispersion imaging of 17O through the use of low-amplitude off-resonance spin-locking pulses (gammaB1 < 300 Hz). Proton spin-lattice relaxation times in the off-resonance rotating frame were measured in H2(17)O-enriched tissue phantoms. On- and off-resonance T1rho dispersion imaging was implemented at 2 T using a spin-locking preparatory pulse cluster appended to a standard spin-echo sequence. On- and off-resonance dispersion images exhibited similar 17O-based image contrast. Magnetization transfer effects did not depend on 17O concentration and had no effect on image contrast. In conclusion, off-resonance proton T1rho dispersion imaging shows promise as a safe, sensitive technique for generating 17O-based T1rho contrast without exceeding SAR limitations.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia 19104-6100, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Charagundla
authors.forename: A H
authors.initials: AH
authors.lastname: Stolpen
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
authors.forename: R
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000042:Absorption; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008433:Mathematics; D008961:Models, Structural; D010103:Oxygen Isotopes; D019047:Phantoms, Imaging; D011522:Protons
chemical_list: D010103:Oxygen Isotopes; D011522:Protons