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

Meyer JMA, Buecker A, Spuentrup E, et al. Improved in-stent magnetic resonance angiography with high flip angle excitation. Invest Radiol 2001;36:677–681. 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°, 100°, and 150° 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° 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°. Composite images of a 30° MIP added to a 150° 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.

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