title: Quantitative T(1rho) and adiabatic Carr-Purcell T2 magnetic resonance imaging of human occipital lobe at 4 T.
abstract: The feasibility of performing quantitative T(1rho) MRI in human brain at 4 T is shown. T(1rho) values obtained from five volunteers were compared with T2 and adiabatic Carr-Purcell (CP) T2 values. Measured relaxation time constants increased in order from T2, CP-T2, T(1rho) both in white and gray matter, demonstrating differential sensitivities of these methods to dipolar interactions and/or proton exchange and diffusion in local microscopic field gradients, which are so-called dynamic averaging (DA) processes. In occipital lobe, all relaxation time constants were found to be higher in white matter than in gray matter, demonstrating contrast denoted as an "inverse transverse relaxation contrast." This contrast persisted despite changing the delay between refocusing pulses or changing the magnitude of the spin-lock field strength, which suggests that it does not originate from DA, as might be induced by the presence of Fe, but rather is related to dipolar interactions in the brain tissue.
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Heidi I
authors.initials: HI
authors.lastname: Gröhn
authors.forename: Shalom
authors.initials: S
authors.lastname: Michaeli
authors.forename: Michael
authors.initials: M
authors.lastname: Garwood
authors.forename: Risto A
authors.initials: RA
authors.lastname: Kauppinen
authors.forename: Olli H J
authors.initials: OH
authors.lastname: Gröhn
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009778:Occipital Lobe / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted