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Objective To assess the effect of iDose4 in image quality and radiation dosage in CT angiography of craniocervical arteries.Methods Imaging data of 50 patients with 256-slice spiral CT angiography of craniocervical arteries were randomly divided into two groups:(A) 120 kV,250 mAs (25 patients),(B) iDose4 100 kV,180 mAs (25 patients).Dose length product (DLP) of the two groups were compared.Objective image noise was compared by two blinded readers,t test and nonparametric tests were used for statistical analysis.Results The overall image quality score of group A (3 points =1 patient,4 points =6 patients and 5 points =18 patients) and group B (4 points =5 patients and 5 points =20 patients) were shown.The image noise of group A (1 point =1 patient,2 points =5 patients and3 points =19 patients) and group B (2 points =4 patients,3 points =21 patients) were also evaluated.There was no statistical difference in revealing rate of image quality scores and objective noise between the two groups (Z =-0.334,-0.218,P ＞ 0.05).The estimated effective radiation dose was reduced by 56％ in group B than in group A.DLP was significantly lower in group B [(642.4 ±36.6) mGy · cm]than in group A [(1462.1 ± 64.3) mGy · cm].Conclusion Low dose contrast medium of CT angiography can display craniocervical arteries and the intracranial arteries very well with high image quality.
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Objective To explore clinical significance of muhidetector(64-row)computed tomography carotid atherosclerosis angiography(MDCTA)in detecting carotid atherosclerotic plaque.Methods Data of 116 patients with carotid atherosclerosis undergone with MDCTA stayed at Huashan Hospital,Shanghai from January to August,2008 were analyzed retrospectively.Results Three hundred and seventy-seven plaques were identified among all the 116 patients in the study,with an incidence of calcified plaque of 63.40 percent,and more detected at the common carotid artery(27.85%).the carotid bifurcation(39.78%)and the internal carotid artery (21.48%).There was significantly statistical difference in plaque types between those with mild,moderate and severe carotid stenosis(P=0.000)and between those aged equal to or lower than 50 years and equal to or greater than 70 years(P=0.005).Plaque types at the common carotid artery were significantly difierent from those at the carotid bifurcation(P=0.000)and at the internal carotid artery(P=0.000).Results of regression analysis showed a positive and significant association between carotid occlusion and clinical symptomatology(with a coefficient of correlation of 1.080.P=0.023)and inverse association between calcified plaque and clinical symptomatology(with a coefficient of correlation of 0.688,P=0.006).Conclusions Not only imaging characteristics of carotid atherosclerotic plaque can be accurately assessed by MDCTA,but also measurement of its stenosis degree.Assessment of plaque type,degree of stenosis and distribution of plaque in different Vascular segments with MDCTA can be used to predict clinical occurrence of cerebevaseular events in patients with carotid atherosclerosis.