Influence of blood-pool contrast media on MR imaging and flow measurements in the presence of pulmonary arterial stents in swine.
OBJECTIVE
To compare the effects of various stents on magnetic resonance (MR) imaging flow volume measurements and to determine the value of a blood-pool MR imaging contrast medium in assessment of vascular stents.


METHODS
In 11 pigs, six nitinol stents (Memotherm), four platinum stents (NuMed), and one elgiloy stent (Wallstent) were placed in the main pulmonary artery under x-ray fluoroscopic guidance. MR imaging was performed 3 months after stent placement before and after injection of NC100150 contrast medium. Blood flow volumes were assessed with velocity-encoded cine MR imaging through and next to the stent. The signal-to-noise ratio and width of susceptibility artifacts of the stents also were determined. Measurements were analyzed with the paired Student t test and Bland-Altman test, where appropriate.


RESULTS
Blood flow volumes measured through the nitinol and platinum stents disclosed no significant difference between velocity-encoded cine MR imaging measurements through and next to the stent. On cine MR images, small susceptibility artifacts were observed around the nitinol and platinum stents. Signal-to-noise ratio in the stent lumen was reduced in nitinol and platinum stents when compared with that next to the stent. The elgiloy stent produced severe susceptibility artifacts, making measurement of flow volumes impossible. NC100150 injection caused no significant effect on flow volume measurements. It improved the signal-to-noise ratio of the pulmonary arterial lumen outside and, to a lesser extent, inside the stent.


CONCLUSIONS
Assessment of morphology and flow volumes through nitinol and platinum stents is feasible with MR imaging. Blood-pool contrast media provide persistent signal enhancement in the pulmonary artery and, to a lesser extent, in the lumina of nitinol and platinum stents.
Kuehne
Titus
T
Department of Radiology, Division of Pediatric Cardiology, University of California San Francisco, 505 Parnassus Ave, L308, San Francisco, CA 94143-0628, USA.
Saeed
Maythem
M
Moore
Phillip
P
Gleason
Kelly
K
Reddy
Gautham
G
Teitel
David
D
Higgins
Charles B
CB
D000497:Alloys; D000704:Analysis of Variance; D000818:Animals; D016477:Artifacts; D001783:Blood Flow Velocity; D003035:Cobalt; D003287:Contrast Media / Q000008:administration & dosage*; D003911:Dextrans; D052203:Ferrosoferric Oxide; D007501:Iron / Q000008:administration & dosage*; D016014:Linear Models; D018810:Magnetic Resonance Angiography; D058185:Magnetite Nanoparticles; D010087:Oxides / Q000008:administration & dosage*; D010984:Platinum; D011651:Pulmonary Artery; D015607:Stents; D013552:Swine
D000497:Alloys; D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; C013616:nitinol; D003035:Cobalt; D010984:Platinum; D007501:Iron; D052203:Ferrosoferric Oxide