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

The aim of the study was the evaluation of electron beam computedtomography as a non-invasive method to localize coronary stentsand to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 ± 7·8 years) withcoronary Palmaz-Schatz stents were examined. Contrast enhancedelectron beam computed tomography using an Evolution scanner(Siemens) and coronary angiography were carried out within 7days of each other. Stent localization was performed using thesingle-slice mode of the electron beam computed tomography scanner.Patency of the coronary target segment was assessed using themulti slice mode after peripheral venous injection of a 40 mlbolus of contrast medium (Ultravist 370). Qualitative imageanalysis of a cine loop of 10 consecutive frames and quantitativeanalysis of densitometric curves in a region of interest distalto the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients(91%), qualitative assessment of contrast enhancement patternsenabled stent patency to be evaluated. In 18 patients (90%),contrast medium was visualized distal to the stent. Quantitativecoronary angiography confirmed that the stented vessel segmentswere not stenosed. Densitometric curves obtained in 16 of these18 patients yielded contrast enhancement distal to the stentedvessel segment of 63 ± 6% compared to the aorta. In onepatient, qualitative and quantitative analysis showed prolongedcontrast enhancement of reduced density, which hinted at a stenosisrelated to the stented vessel segment. Coronary angio graphyrevealed subtotal occlusion of the stented vessel directly distalto the stent. In another patient, no contrast visualizationof the vessel distal to the stent was achieved. Coronary angiographyrevealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronarystents and may become a useful tool for providing informationon stented vessel segment patency. (Eur Heart J 1996; 17: 1546–1553)