Measurement of T1, T2, and magnetization transfer properties during embryonic development at 7 Tesla using the chicken model.
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.
Boss
Andreas
A
Section of Experimental Radiology, Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University of Tübingen, Tübingen, Germany. andreas.boss@med.uni-tuebingen.de
Oppitz
Matthias
M
Wehrl
Hans F
HF
Rossi
Cristina
C
Feuerstein
Markus
M
Claussen
Claus D
CD
Drews
Ulrich
U
Pichler
Bernd J
BJ
Schick
Fritz
F
D000818:Animals; D002642:Chick Embryo / Q000254:growth & development*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*