| Objective1. To compare the HDCT imaging of high-definition scan mode with standard-definition in vitro.2. To compare the HDCT imaging of high-definition scan mode with standard-definition in patients underwent coronary stenting.3. To evaluate the advantage of high-definition scan mode in imaging different diameter stents.Material and Methods1. Ten coronary artery stents of different material and diameter were studied. Five stents were made of stainless surgical steel(316L),five of a cobalt-chromium alloy(L605),with diameters of2.5mm,2.75mm,3.0mm,3.5mm and4.0mm. All stents were implanted in a coronary vessel phantom made of a plastic tube filled with contrast material. Images were acquired on a HDCT scanner, the Discovery CT750HD, with two scan mode of high-definition and standard-definition and repeated scanning of316L stents9times. Tube voltage120kV, effective tube current450mA, simulate heart rate was60bpm. After examination, scan data transferred to AW4.4workstation was analysed in curved planar reformations and straightened vessel reformations. To measure inner stent diameter (ISD) using electronic calipers, attenuation values(AV) inside the visible stent lumen,and attenuation values inside the non-stented lumen of vessel models using a region of interest (ROI) technique. All stents were evaluated in a window width of1200-1500HU and a center of300-500HU. To calculate and compare the visibility and in-stent attenuation increase value of two group, using paired t test. At p<0.05statistical significance is assumed.2. fifty-five patients undergent coronary stenting taking a CTCA examination were sequently selected and randomly divided into two groups A and B. Group A,29cases (male12,female9), mean age (57.6±9.5), mean BMI (27.7±2.7)kg/m2,49stents were implanted. Group B,26cases(male19,female7),mean age (61.5±10.7), mean BMI (25.9±2.9) kg/m2,47stents were implanted. All the patients with heart rate more than65bpm orally took β-blocker. All cases were scanned with prospective ECG-gating, tube voltage120kV,tube current set according to BMI(350mA-690mA).Axial imagings transferred to AW4.4workstation were analysed in curved planar reformations and straightened vessel reformations. To measure inner stent diameter (ISD) use electronic calipers. To assess maging quality by3-point. To calculate the mean visibility of two groups and the visibility of different type stents. A t test was used to compare the visibility between two groups.Results1. The visibility of HD group (49.2±8.9)%, NHD group (45.9±10.0)%, there was a statistical difference of the measured inner stent diameter (p<0.05). The visibility of HD group was7.2%higher than NHD group’s. The in-stent attenuation increase of HD group was (50.0±21.0) HU, lower59.8%than that of NHD group. There was a statistical difference (p<0.05). There were statistical differences of the in-stent attenuation increase in every diametral stent of316L. For stents diameter of2mm and4mm of316L, there was no statistical difference in visibility.2.44stents were accepted. The mean points of imaging quality of group A was3.5, group B3.2, there was a statistical difference (P<0.05). the average visibility of group A was(56.5±9.2)%, group B (49.5±9.4)%. there was a statistical difference (P<0.05).For the visibility of stents with diameter of2.5mm or≥4.0mm, there was no statistical difference between two groups, and diameter of2.75mm,3.0mm,3.5mm, there were statistical difference.ConclusionThe high-definition scan mode of HDCT is better than standard-definition to visualize stents with diameter of2.75mm to4mm. For the visualizing stents diameter <2.75mm or≥4.0mm, there is no statistical difference between two groups. |
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