title: Phase shift due to inversion recovery process and chemical shift effect in inversion recovery prepared gradient-echo magnetic resonance imaging.
abstract: 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.
authors.affiliation: Department of Radiology, Sapporo Medical University, School of Medicine, S-1 W-16, Chuoku, Sapporo, Hokkaido 060-8543, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Yama
authors.forename: Miki
authors.initials: M
authors.lastname: Takeda
authors.forename: Mitsuharu
authors.initials: M
authors.lastname: Tamakawa
authors.forename: Hidenari
authors.initials: H
authors.lastname: Akiba
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Koito
authors.forename: Masato
authors.initials: M
authors.lastname: Hareyama
mesh_terms: D003287:Contrast Media; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA