title: In vivo measurement of transverse relaxation time in the mouse brain at 17.6 T.
abstract: OBJECTIVE
  To establish regional T1 and T2 values of the healthy mouse brain at ultra-high magnetic field strength of 17.6 T and to follow regional brain T1 and T2 changes with age.
  
  
  METHODS
  In vivo T1 and T2 values in the C57BL/6J mouse brain were followed with age using multislice-multiecho sequence and multiple spin echo saturation recovery with variable repetition time sequence, respectively, at 9.4 and 17.6 T. Gadolinium-tetra-azacyclo-dodecane-tetra-acetic acid phantoms were used to validate in vivo T2 measurements. Student's t-test was used to compare mean relaxation values.
  
  
  RESULTS
  A field-dependent decrease in T2 is shown and validated with phantom measurements. T2 values at 17.6 T typically increased with age in multiple brain regions except in the hypothalamus and the caudate-putamen, where a slight decrease was observed. Furthermore, T1 values in various brain regions of young and old mice are presented at 17.6 T. A large gain in signal-to-noise ratio was observed at 17.6 T.
  
  
  CONCLUSIONS
  This study establishes for the first time the normative T1 and T2 values at 17.6 T over different mouse brain regions with age. The estimates of in vivo T1 and T2 will be useful to optimize pulse sequences for optimal image contrast at 17.6 T and will serve as baseline values against which disease-related relaxation changes can be assessed in mice.
authors.affiliation: Solid State NMR, Leiden Institute of Chemistry, Gorlaeus Laboratoria, Leiden, The Netherlands.
authors.forename: Firat
authors.initials: F
authors.lastname: Kara
authors.forename: Fu
authors.initials: F
authors.lastname: Chen
authors.forename: Itamar
authors.initials: I
authors.lastname: Ronen
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: de Groot
authors.forename: Jörg
authors.initials: J
authors.lastname: Matysik
authors.forename: A
authors.initials: A
authors.lastname: Alia
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D003198:Computer Simulation; D005260:Female; D006571:Heterocyclic Compounds; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D008959:Models, Neurological; D009942:Organometallic Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate