title: Measurement of T1, T2, and magnetization transfer properties during embryonic development at 7 Tesla using the chicken model.
abstract: OBJECTIVE
  To evaluate whether techniques of high field magnetic resonance imaging may be used to characterize embryonic tissue during proliferation and differentiation.
  
  
  METHODS
  Thirteen chicken embryos with incubation times between 5 days and 16 days have been measured in a small animal magnetic resonance imager (ClinScan, Bruker) at 7 Tesla using the built-in resonator. T1, T2-, and magnetization transfer imaging was performed using fast spin-echo with inversion recovery, half acquisition single shot turbo spin-echo, and spoiled gradient-echo sequences with and without off-resonance pulse, respectively. T1, T2, and magnetization transfer ratio (MTR) maps were calculated on a pixel-by-pixel basis.
  
  
  RESULTS
  T1-, T2-, and MTR maps showed good image quality allowing for delineation of embryonic organs. During embryonic development, a decrease of T1 and T2 relaxation times was found, whereas, embryonic tissue typically showed an increase of magnetization transfer, for example, liver properties at day 5: T1 = 2431 +/- 163 ms, T2 = 122 +/- 12 ms, MTR = 9.2 +/- 4.2%; liver properties at day 16: T1 = 1763 +/- 89 ms, T2 = 71 +/- 4 ms, MTR = 16.9 +/- 2.2%.
  
  
  CONCLUSIONS
  Embryonic tissues show changing relaxation and magnetization transfer properties during development, therefore, high field MRI seems suitable for characterization of tissue replacement derived from embryonic stem cells.
authors.affiliation: Section of Experimental Radiology, Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University of Tübingen, Tübingen, Germany. andreas.boss@med.uni-tuebingen.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
authors.forename: Matthias
authors.initials: M
authors.lastname: Oppitz
authors.forename: Hans F
authors.initials: HF
authors.lastname: Wehrl
authors.forename: Cristina
authors.initials: C
authors.lastname: Rossi
authors.forename: Markus
authors.initials: M
authors.lastname: Feuerstein
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Drews
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Pichler
authors.forename: Fritz
authors.initials: F
authors.lastname: Schick
mesh_terms: D000818:Animals; D002642:Chick Embryo / Q000254:growth & development*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*