Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography

UNLABELLED: The aim of the study was the evaluation of electron beam computed tomography as a non-invasive method to localize coronary stents and to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 +/- 7.8 years) with coronary Palmaz-Schatz stents were examined. Contrast enhanced electron beam computed tomography using an Evolution scanner (Siemens) and coronary angiography were carried out within 7 days of each other. Stent localization was performed using the single-slice mode of the electron beam computed tomography scanner. Patency of the coronary target segment was assessed using the multi-slice mode after peripheral venous injection of a 40 ml bolus of contrast medium (Ultravist 370). Qualitative image analysis of a cine loop of 10 consecutive frames and quantitative analysis of densitometric curves in a region of interest distal to the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients (91%), qualitative assessment of contrast enhancement patterns enabled stent patency to be evaluated. In 18 patients (90%), contrast medium was visualized distal to the stent. Quantitative coronary angiography confirmed that the stented vessel segments were not stenosed. Densitometric curves obtained in 16 of these 18 patients yielded contrast enhancement distal to the stented vessel segment of 63 +/- 6% compared to the aorta. In one patient, qualitative and quantitative analysis showed prolonged contrast enhancement of reduced density, which hinted at a stenosis related to the stented vessel segment. Coronary angiography revealed subtotal occlusion of the stented vessel directly distal to the stent. In another patient, no contrast visualization of the vessel distal to the stent was achieved. Coronary angiography revealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronary stents and may become a useful tool for providing information on stented vessel segment patency.