MSCT Evaluation Before And After Coronary Stent Operation

1. Ability of64-sfice spiral CT in demonstrating coronary collateral circulation:comparing with coronary angiographyObjective:To evaluate the ability of64-slice spiral CT(64-MSCT) in demonstrating coronary collateral circulation(CCC).Methods:Retrospectively analysis58patients’imaging of64-MSCT coronary angiography, which manifested at least one major coronary artery with complete or sub-total occlusion. Taking traditional coronary angiography (CAG) as the reference standard, we evaluated the accuracy of the64-MSCT to detect the CCC and analyzed the misdiagnosis and missed diagnosis of MSCT according to the Rentrop grading.Results:Among the58patients, at least one CCC was found by CTA in27patients, and at least one CCCwas detected by CTA. Taken the CAG results as the reference standard, the sensitivity and specificity of the CTA in detecting patients with the CCCs were88.9%(24/27) and91.2%(31/34) retrospectively. The14misdiagnosis were all CAG-1in Rentrop grading, and the12misdiagnosis included1CAG-lgroup,8CAG-2group,3CAG-3group.Conclusion:64-MSCT angiography can accurately evaluate the coronary collateral circulation. 2. In-Vitro evaluation of coronary stents by HDCT:An experimental studyObjective:To assess the ability of HDCT in diagnosing the stenosis of coronary stents and the true lumen.Methods:Six Excel stents (2.75×18mm) were dilated to different stent with the diameters of2.75mm,3.0mm,3.5mm by the balloon dilatation catheters. They were divided into three groups A, B, C and were established stenosis models of0%,30%,50%,70-80%which demonstrated non-stenosis, low-grade stenosis, intermediate stenosis, high-grade stenosis. All stents were filled with iodinated contrast, submerged in water, and scanned by GSI scanning mode. Reconstruct40-140keV monochromatic energy images and material decomposition images and mixed energy images and analyze the visibility rate and stenosis of stents.50-60keV monochromatic energy images have better image quality in displaying mixed plaques of coronary stents. The diagnostic accuracy of non-, low-grade, intermediate, high-grade stenosis increased by16.67%,33.33%,16.66%,16.67%respectively.Results:Water-based material decomposition images and140-keV monochromatic energy images can display stents with least artifacts, but the latter have better resolusion of the stent lumen which helps diagnosing different stenosis. Effective atomic number images can help to differentiate plaques and artifacts in stents.Conclusions:40-140keV monochromatic energy images are suitable for displaying stent structure:50-60keV monochromatic energy images can be used for diagnosing stent restenosis. Spectral substance analysis apply to differentiate plaques and artifacts in stents. Spectral CT provides a more accurate measurement of true stent lumen and stenosis of coronary stents. 3. Coronary artery stent luminal visibility:comparison between GE SDCT and GE HDCTObjective:To prospectively evaluate luminal visibility of the coronary artery stent imaging performance of GE HDCT(High-definition multidetector computed tomography) and compare it with GE LightSpeed VCT.Methods:6months after the stent implantation,52patients (85stents implanted) received assessment by VCT, and HDCT after one year as following examination. Coronary images with stents were visually compared between the two systems. In addition, stent lumen diameter and CT value, and CT number of vascular segments before and after implantation were measured. The spatial resolution and stent beam hardening impact on the evaluation of the in-stent lumen was studied using the CT value difference and the diameter ratio between the in-stent and proximal lumens.Results:Stents and in-stent lumens were more clearly visualized on HDCT than VCT with significantly difference (69.0%by HDCT vs.42.9%by VCT; P<0.01). The average increase of CT value of the in-stent lumen as compared with the un-stented segments was15.2HU with HDCT and54.2HU with VCT (P<0.01).Conclusion:With the improved spatial resolution, image reconstruction algorithm and effective restrain from beam hardening artifact, HDCT improves the clarity for imaging coronary stents for better re-stenosis evaluation, and provides more accurate measurement for in-stent lumen diameter compared with VCT.