Improved In-Stent Magnetic Resonance Angiography With High Flip Angle Excitation

Invest Radiol. 2001 Nov;36(11):677-81. doi: 10.1097/00004424-200111000-00007.


Rationale and objectives: To optimize the intraluminal signal intensity of a nitinol stent by performing contrast-enhanced three-dimensional magnetic resonance angiography (CE-MRA) with varying flip angles (FAs).

Methods: Contrast-enhanced magnetic resonance angiography at 1.5 T and FAs of 30 degrees, 100 degrees, and 150 degrees was performed on five sheep with 10 iliac nitinol stents (Memotherm-FLEXX). Maximum-intensity projections (MIPs) and composite images of MIPs were performed and compared.

Results: Reconstructed MIPs at an FA of 150 degrees showed a slightly disturbed lumen visibility inside the stent accompanied by low-grade lumen visibility outside the stent and vice versa for an FA of 30 degrees. Composite images of a 30 degrees MIP added to a 150 degrees MIP resulted in improved image quality compared with the standard MIP of a single FA.

Conclusions: Signal loss due to radiofrequency shielding inside nitinol stents imaged by CE-MRA can be reduced by applying high FAs. Composite MIP images allow simultaneous visualization of the lumen inside as well as outside the stent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alloys
  • Animals
  • Contrast Media
  • Gadolinium DTPA
  • Iliac Artery / pathology
  • Iliac Artery / surgery
  • Magnetic Resonance Angiography / methods*
  • Male
  • Sheep
  • Stents*


  • Alloys
  • Contrast Media
  • nitinol
  • Gadolinium DTPA