Efficiency of ultrasonography and CT angiography in follow-up studies of carotid stent and percutaneous transluminal angioplasty

The aim of this study was to determine a more appropriate method for follow-up of carotid stenting by comparing the efficiency of US and CT angiography. Eleven carotid arteries of seven patients(men:5, women:2, mean age:56.4years) who underwent stent placement and percutaneous transluminal angioplasty(PTA) because of carotid stenosis were studied. The follow-up periods ranged from three to eleven (mean, five) months, and US and CT angiography were performed in one day. Color duplex sonography was performed with a 10 MHz linear array transducer. After spiral CT scan were obtained, MPR images were reconstructed on a workstation. Retrospective imaging analysis specifically focused on [1] stent configuration, [2] the accuracy of internal diameter measurement, [3] the detection of blood flow and the measurement of blood flow velocity, [4] the presence of atheroma and intraluminal thrombi, [5] the measurement of stent location, and [6] artifacts. US was more accurate than CT angiography for measuring internal diameter. In all cases, US and CT angiography were able to detect the blood flow at carotid artery, and utilizing the Doppler spectrum, flow velocity was measured. US showed atheromas in all cases but CT angiography demonstrated calcified atheromas in three cases only. In six cases, US failed to determine stent location, though in this respect CT angiography was successful in all cases. Artifacts of US were small reverberation artifact(11/11) of the stent and a defective color Doppler signal caused by acoustic shadowing of atheroma calcification(3/11). Artifacts of CT angiogrpahy were hardbeam artifact of the stent(11/11) and motion artifact(3/11). US was superior to CT angiography in accuracy of measuring stent diameter, hemodynamic assessment, high-resolution views of the luminal state of the stent and minimal artifacts for the non-invasive follow-up studies of carotid stenting