Carotid artery stents: in vitro comparison of different stent designs and sizes using CT angiography and contrast-enhanced MR angiography at 1.5T and 3T.

BACKGROUND AND PURPOSE CT angiography (CTA) and MR angiography (MRA) are increasingly used methods for evaluation of stented vessel segments. Our aim was to compare CTA, contrast-enhanced MRA (CE-MRA) at 1.5T, and CE-MRA at 3T for the visualization of carotid artery stents and to define the best noninvasive imaging technique as an alternative to conventional angiography for each stent. MATERIALS AND METHODS CTA and CE-MRA appearances of 18 carotid artery stents of different designs and sizes (4.0 to 10.0 mm) were investigated in vitro. For each stent, artificial lumen narrowing (ALN) was calculated. RESULTS With CE-MRA at 3T and at 1.5T, ALN in most nitinol stents was lower than that in the groups of stainless steel and cobalt alloy stents. In most nitinol stents and in both cobalt alloy stents, ALN was lower on CE-MRA at 3T than at 1.5T. In all stainless steel stents, ALN was lower on CTA than on CE-MRA. With CTA and CE-MRA, in most stents ALN decreased with increasing stent diameter. CONCLUSIONS CTA and CE-MRA evaluation of vessel patency after stent placement is possible but is considerably impaired by ALN. Investigators should be informed about the method of choice for every stent. Stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic methods such as CTA and CE-MRA.