nclude positive vascular remodeling,low plaque density,spotty calcification,and eccentric stenosis.

Objective To explore the accuracy of high definition computed tomography angiography (HDCTA)in the evaluation of coronary in-stent restenosis.Methods 93 patients with 159 implanted coronary stents who underwent both HDCTA and CAG were included in the study.The sensitivity,specificity,positive predictive value (PPV),negative predictive value (NPV)and diag-nostic accordance rate of HDCTA were calculated.The imaging quality was analyzed by visual estimation.Possible factors that in-fluenced the diagnostic accuracy of HDCTA were evaluated,which included stent location,stent diameter and heart rate in the pa-tients with left anterior descending branch stents.Results Restenosis was found in 21 stents by CAG and 19 stents by HDCTA.The false positive and false negative were 5 and 3,respectively.Sensitivity,specificity,PPV,NPV and diagnostic accordance rate were 90.5%,96.4%,79.2%,98.5% and 95.6% respectively.The image quality was 4 score in 75 stents (47.1%),3 score in 33 (20.8%),2 score in 27 (17%),≤1 score in 24 (15.1%).The image quality of proximal segments,large stents (≥3.0 mm)and slow heart rate (<66 beast per minute)was significantly better than that of distal segments,small stents (<3.0 mm)and fast heart rate (≥6 6 beast per minute).Conclusion HDCTA is a convenient,efficient and non-invasive method for follow-up after im-plantation of the coronary artery stents.

Purpose To investigate the diagnostic value of the arrhythmogenic right ventricular dysplasia (ARVD) using multi-slice spiral CT (MSCT). Materials and Methods Thirty-four patients who were suspected as ARVD received right ventricular radiography, including 16 ARVD patients and 15 non-ARVD patients regarded as control group. The structural and shaped change of heart on reconstructed images of long axis, short axis and four cavity surface and analyze were observed, and MSCT features of right ventricular radiography characteristics were analyzed for ARVD patients. Results Sixteen cases of ARVD were correctly diagnosed by MSCT, and 14 cases had fatty infiltration including 11 cases of apex of heart, 8 cases of inferior wall, 5 cases of anterior wall, 5 cases of anterior wall of funnel area, 3 cases of diagram, 4 cases of papillary muscle, 6 cases of muscular trabecula and moderator band and 1 case of whole right ventricular free wall. Five cases showed scallop sign, 16 cases excessive trabecular change, 11 cases thinned changes, and 16 cases enlarged changes of right ventricular wall. Conclusion MSCT features of right ventricular for ARVD have relative diagnostic characteristics, and the scallop sign and excessive trabecular change of right ventricular wall are its specific imaging characteristics.

Objective To evaluate images quality and diagnostic feasibility of low-dose CT in patients with traumatic rib fractures.Methods Twenty-five patients presented with thoracic iniury were underwent 64-slice spiral CT scanning in inspiration breath-hold technique.Two scan protocols were performed.In one scan protocol noise index(NI)is 11,and in another NI is 21,but the other scan parameters were no difference.The mean value of tube current,the volume CT dose index(CTDIvol),and effective dose(ED)were recorded.Image quality was scored by 2 experienced radiologists using the 5-points scale.The numbers and degrees of rib fractures were recorded.The data were tested by using the Wilcoxon signed rank sum test.The differences of the inter-observer were determined by Kappa statistics.Results The mean CTDIvol and ED in scan protocol with NI of 11 were(13.88±5.17)mGy and(8.14±3.21)mSv,and that with NI of 21 were(3.91±1.57)mGy and(2.31±0.97)mSv.Compared the scan with NI of 11.there was 72%intrinsie dose reduction in the scan with NI of 21.The mean value of tube current in scan with NI of 11 and 21 were(195.88±69.33)mAs and(54.56±21.54)mAs.AIl patients with 11 and Ⅲ degree and most patients with I degree rib fractures that identified by the scan with NT of 11 were detected by the scan with NI of 21.There were no statistical difference between two scaus with the Wilcoxon signed rank sum test.The diagnostic acceptability and image noise score in the scan with NI of 11 were 4.9±0.2 and 4.6±0.5.and that with NI=21 were 3.5±0.5 and 3.3±0.5.There was prefect concordante in the inter-observers in diagnostic acceptability on finding of rib fractures.diagnostic acceptability and image noise(Kappa=0.876,0.820,0.792,P<0.01)between two scan protocols.Conclusion Rib fractures can be diagnosed by the low-dose CT using the scan protocol with NI of 21.

Objective To evaluate accuracy of density measurements within coronary plaque by multi-slice spiral CT and factors that influence measurements. Methods Four adult cadaver hearts were used. Thrombus and pericardial fat which acquired from specimen (size 2.0, 1.5, 1.0 and 0.5 mm respectively) were placed into coronary artery to simulate coronary plaques. The contrast medium (three different concentrations 1: 30, 1:40, and 1:50) were injected into coronary artery. The raw date were reconstructed with two slice width ( 1. 00 and 0. 75 mm). Results When contrast medium concentrations was 1: 30, the CT values of thrombus were 109 HU ( slice width 1. 00 mm, size 2. 0 mm) , 115 HU ( slice width 1.00 mm, size 1.5 mm), 101 HU (slice width 0.75 mm, size 2.0 mm), 113 HU ( slice width 0. 75 mm,size 1. 5 mm) ; the CT values of fat were - 23 HU ( slice width 1. 00 mm, size 2. 0 mm) , -17 HU(slice width 1.00 mm, size 1.5 mm) , -9 HU(slice width 1.00 mm, size 1.0 nun), -27 HU ( slice width 0.75 mm, size 2. 0 mm) , - 19 HU (slice width 0.75 mm, size 1. 5 mm) , - 13 HU (slice width 0. 75 mm,size 1. 0 mm). When contrast medium concentrations was 1: 40, the CT values of thrombus were 79 HU( slice width 1.00 mm,size 2.0 mm) , 87 HU( slice width 1.00 mm, size 1. 5 mm) , 115 HU( slice width 1. 00 mm,size 1. 0 mm) , 73 HU(slice width 0. 75 mm,size 2. 0 mm) , 80 HU(slice width 0. 75 mm, size 1. 5 mm) , 110 HU( slice width 0. 75 mm, size 1. 0 mm) ; the CT values of fat were - 31 HU ( slice width 1. 00 mm, size 2. 0 mm) , - 22 HU ( slice width 1. 00 mm, size 1. 5 mm) , - 10 HU ( slice width 1.00 mm,size 1.0 mm) , -35 HU(slice width 0. 75 mm,size 2.0 mm) , -25 HU(slice width 0. 75 mm, size 1. 5 mm) , - 19 HU ( slice width 0. 75 mm, size 1. 0 mm). When contrast medium concentrations was 1:50, the CT values of thrombus were 53 HU ( slice width 1. 00 mm, size 2. 0 mm) , 60 HU ( slice width 1.00 mm,size 1.5 mm) ,63 HU(slice width 1.00 mm,size 1.0 mm) ,51 HU(slice width 0.75 mm,size 2. 0 mm) ,64 HU( slice width 0. 75 mm,size 1. 5 mm) ,67 HU( slice width 0. 75 mm,size 1. 0 mm) ,145 HU (slice width 0. 75 mm, size 0. 5 mm) ; the CT values of fat were - 39 HU ( slice width 1. 00 mm, size 2. 0 mm) , -28 HU( slice width 1. 00 mm,size 1. 5 mm) , - 22 HU( slice width 1. 00 mm,size 1. 0 mm) , 17 HU(slice width 1. 00 mm,size 0. 5 mm) , -41 HU(slice width 0. 75 mm,size 2. 0 mm), -36 HU(slice width 0. 75 mm, size 1. 5 mm ) , - 27 HU ( slice width 0. 75 mm, size 1. 0 mm ) , 3 HU ( slice width 0. 75 mm, size 0. 5 mm ) . The density values of thrombus were correlated with size ( t = - 6. 624, P 0. 05) not found statistically significant may be caused by both too close slice width (1.0 mm and 0. 75 mm) and few samples. The slice width(t= -2. 595,P