Phase shift due to inversion recovery process and chemical shift effect in inversion recovery prepared gradient-echo magnetic resonance imaging.
OBJECTIVE
The purpose of this study was to assess phase shift due to the inversion recovery process and the chemical shift effect in inversion recovery prepared gradient-echo magnetic resonance imaging.


METHODS
The signal intensities of three phantoms, composed of physiologic saline solution with Gd-DTPA, olive oil, and fat emulsion, were measured on a 1.5 Tesla unit. The sequence was single-shot two-dimensional. The parameters were as follows: TI 100-2500 msec at 100 msec intervals, TR 11.25 msec, TE 2.250 msec, 3.375 msec, and 4.500 msec. The k-space was filled with the centric view order.


RESULTS
The signal intensity curves of the emulsion showed various patterns. At a TE of 2.250 msec, TI at the minimum value of signal intensity was 1500 msec. At a TE of 4.500 msec, TI at the minimum value was 500 msec. Up to a TI of 1000 msec, the signal intensity at a TE of 2.250 msec was stronger than that at a TE of 4.500 msec, and from a TI of 1000 msec, the signal intensity at a TE of 4.500 msec was stronger than that at a TE of 2.250 msec.


CONCLUSIONS
We concluded that fat emulsion showed paradoxical phase shift.
Yama
Naoya
N
Department of Radiology, Sapporo Medical University, School of Medicine, S-1 W-16, Chuoku, Sapporo, Hokkaido 060-8543, Japan.
Takeda
Miki
M
Tamakawa
Mitsuharu
M
Akiba
Hidenari
H
Koito
Kazumitsu
K
Hareyama
Masato
M
D003287:Contrast Media; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted
D003287:Contrast Media; D019786:Gadolinium DTPA