Contrast-Enhanced MR Angiography at 1.5 T After Implantation of Platinum Stents: In Vitro and In Vivo Comparison with Conventional Stent Designs

Contrast-Enhanced MR Angiography at 1.5 T After Implantation of Platinum Stents: In Vitro and In Vivo Comparison with Conventional Stent Designs

Klaus D. Hagspiel¹, D. A. Leung¹, Kiran R. Nandalur¹, John F. Angle¹, Harjot S. Dulai², David J. Spinosa¹, A. H. Matsumoto¹, J. M. Christopher², Hossam Ahmed² and S. S. Berr¹^,3

¹ Department of Radiology, Division of Interventional Radiology, University of Virginia Health System, Box 800170, Charlottesville, VA 22908.
² University of Virginia Medical School, Charlottesville, VA.
³ Department of Biomedical Engineering, University of Virginia, Charlottesville, VA.

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Fig. 1A. —MR angiograms and radiographic images of four balloon-expandable stents and three self-expandable stents. MR angiography was performed with flip angle of 30°; MR angiography images are maximum-intensity-projection images rendered from original data. MR angiograms (left) and radiographs (right) show four balloon-expandable stents (from top to bottom): Corinthian (Cordis), Palmaz (Cordis), Vistaflex (Angiodynamics), and NIR (Boston Scientific) dilated to 6 mm.

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Fig. 1B. —MR angiograms and radiographic images of four balloon-expandable stents and three self-expandable stents. MR angiography was performed with flip angle of 30°; MR angiography images are maximum-intensity-projection images rendered from original data. MR angiograms (left) and radiographs (right) show balloon-expanded Vistaflex stent, which is composed of platinum, compared with three self-expandable stents made from nitinol or tantalum. Stents shown are Symphony (Boston Scientifc), Vistaflex (Angiodynamics), Strecker (Boston Scientifc), and Memotherm (Bard Angiomed) from top to bottom, respectively.

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Fig. 2. —76-year-old woman after placement of P204 Palmaz stent (Cordis) in left subclavian artery. Three-dimensional contrast-enhanced MR angiogram (left) shows 100% occlusion (grade 0 lumen visibility). Note also stenosis of subclavian artery distal to origin of costocervical trunk is overestimated. Digital subtraction angiogram (right) shows complete patency of lumen.

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Fig. 3. —68-year-old woman after placement of Vistaflex stent (Angiodynamics) in left subclavian artery. MR angiogram (left) shows patency of lumen of subclavian artery with indwelling stent. Corresponding subvolume maximum-intensity-projection image of 3D gadolinium-enhanced MR angiography (right) shows patent lumen. Assessment of patency was affected only minimally by stent artifacts (grade 2 lumen visibility).

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Fig. 4. —69-year-old man after placement of two overlapping Palmaz stents (Cordis) in left renal artery. Selective catheter angiogram (left) obtained after stent placement shows 100% patency of lumen. Three-dimensional contrast-enhanced MR angiogram (top right) shows complete occlusion of lumen due to stent artifacts (grade 0 lumen visibility). Bottom right image is magnified view.

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Fig. 5. —55-year-old woman after placement of Omniflex stent (Angiodynamics) in right renal artery. Source image of contrast-enhanced MR angiography (left) shows grade 2 artifact confirming patency. Selective angiogram (right) obtained after stent placement confirms patency.

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Fig. 7A. —57-year-old woman after undergoing renal transplantation and placement of femorofemoral bypass graft from right to left due to left common external iliac occlusion. Vistaflex stent (Angiodynamics) is in right common iliac artery. Subtraction 3D gadolinium-enhanced MR angiogram (left) shows patent distal aorta, focal ectasia of right common iliac artery with stenosis in its distal portion, and patent transplant renal artery and femorofemoral bypass graft. Corresponding CO₂ catheter angiogram (right) shows stenosis distal to stent and patent femorofemoral bypass graft.

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Fig. 7B. —57-year-old woman after undergoing renal transplantation and placement of femorofemoral bypass graft from right to left due to left common external iliac occlusion. Vistaflex stent (Angiodynamics) is in right common iliac artery. Four oblique coronal multiplanar reformatted images (left) obtained through common iliac artery and Vistaflex stent show there is minimal artifact due to stent (grade 2 lumen visibility). Significant stenosis distal to stent, which was treated with percutaneous transluminal angoplasty, is also visible. Magnified CO₂ angiogram (right) shows similar findings; however, because of poor contrast resolution of CO₂, diagnosis is less evident.

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Fig. 6. —62-year-old man with Corinthian stent (Cordis) in right common iliac artery and Intrastent (Sulzer Intratherapeutics) in left common iliac artery. Maximum-intensity-projection image (left) and multiplanar reformatted images (top right) through stent's lumen show significant reduction of luminal patency due to stent artifacts (grade 1 lumen visibility for both stents). Digital angiogram (bottom right) obtained immediately after stent placement shows patency of both common iliac arteries.

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Fig. 8A. —46-year-old woman with Express stents (Boston Scientific) in bilateral common iliac arteries. Right stent was dilated to 6 mm, and left stent was dilated to 8 mm. Angiogram shows 100% patency after stenting of common iliac arteries.

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Fig. 8B. —46-year-old woman with Express stents (Boston Scientific) in bilateral common iliac arteries. Right stent was dilated to 6 mm, and left stent was dilated to 8 mm. Three-dimensional contrast-enhanced MR angiogram shows significant artifact-related stenoses. Stenosis on left side with larger stent is less severe (left, 48% stenosis; right, 95% stenosis). Both sides were graded as 1 (reduced visibility, insufficient to rule out significant stenosis).

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