title: Proton T1rho-dispersion imaging of rodent brain at 1.9 T.
abstract: Detection of H2(17)O with proton T1rho-dispersion imaging holds promise as a means of quantifying metabolism and blood flow with MRI. However, this technique requires a priori knowledge of the intrinsic T1rho dispersion of tissue. To investigate these properties, we implemented a T1rho imaging sequence on a 1.9-T Signa GE scanner. A series of T1rho images for different locking frequencies and locking durations were obtained from rat brain in vivo and compared with 5% (wt/vol) gelatin phantoms containing different concentrations of (17)O ranging from .037% (natural abundance) to 2.0 atom%. Results revealed that, although there is considerable T1rho-dispersion in phantoms doped with H2(17)O, the T1rho of rat brain undergoes minimal dispersion for spin-locking frequencies between .2 and 1.5 kHz. A small degree of T1rho dispersion is present below .2 kHz, which we postulate arises from natural-abundance H2(17)O. Moreover, the signal-to-noise ratios of T1rho-weighted images are significantly better than comparable T2-weighted images, allowing for improved visualization of tissue contrast. We have also demonstrated the feasibility of proton T1rho-dispersion imaging for detecting intravenous H2(17)O on a live mouse brain. The potential application of this technique to study brain perfusion is discussed.
authors.affiliation: Metabolic Magnetic Resonance and Computing Center, Department of Radiology, University of Pennsylvania, Philadelphia 19104-6100, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Rizi
authors.forename: S R
authors.initials: SR
authors.lastname: Charagundla
authors.forename: H K
authors.initials: HK
authors.lastname: Song
authors.forename: R
authors.initials: R
authors.lastname: Reddy
authors.forename: A H
authors.initials: AH
authors.lastname: Stolpen
authors.forename: M D
authors.initials: MD
authors.lastname: Schnall
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D005240:Feasibility Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D010103:Oxygen Isotopes; D019047:Phantoms, Imaging; D051381:Rats
chemical_list: D010103:Oxygen Isotopes