title: Delineation of simulated vascular stenosis with Gd-DTPA-enhanced 3D gradient echo MR angiography: an experimental study.
abstract: OBJECTIVE
  The purpose of this experimental study was to evaluate the influence of contrast material concentration and flow velocity on pulsatile flow in Gd-DTPA-enhanced 3D gradient echo MR angiographic sequence.
  
  
  METHODS
  In vivo flow experiments were performed in Plexiglas phantoms with artificial stenosis (50% stenotic ratio and 20 mm stenotic length) attached to a cardiac pump that generated physiological pulsatile flow similar to that of the bloodstream in a closed circuit. We used a steady-state gradient echo sequence with different TEs (6, 3, and 1.4 ms). A TR of 15 ms was used for all parameters. The concentration of Gd-DTPA varied from 0 to 2.0 mmol/L and flow velocities from 25 to 80 cm/s. We measured the degree of stenosis and length of stenosis in comparison with the actual values.
  
  
  RESULTS
  The degree and length of stenosis on 3D gradient echo MR angiographic images were markedly influenced by the velocity of the flow and concentration of Gd-DTPA. The degree of stenosis was overestimated when the flow was fast or when the concentration of Gd-DTPA was low. When the concentration of Gd-DTPA was low, stenosis was elongated. These effects were less prominent on short TE (1.4 ms) sequence.
  
  
  CONCLUSIONS
  The stenotic lesions were markedly overestimated on MR angiographic images obtained with Gd-DTPA-enhanced fast 3D gradient echo sequence. Spin dephasing can be compensated for almost entirely by a high concentration of Gd-DTPA and/or a short TE sequence.
authors.affiliation: Department of Radiology, Kumamoto University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Mitsuzaki
authors.forename: Y
authors.initials: Y
authors.lastname: Yamashita
authors.forename: M
authors.initials: M
authors.lastname: Onomichi
authors.forename: T
authors.initials: T
authors.lastname: Tsuchigame
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D001157:Arterial Occlusive Diseases / Q000175:diagnosis*; D001783:Blood Flow Velocity; D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA