| Purpose:To explore the feasibility of low radiation dose and concentration contrast media intracranial and cervical arteries CTA,by comparing the effects of different tube voltage and concentrations of iodine contrast media on the image quality of intracranial and cervical arteries CTA,Methods:1.Conduct volume scanning on the vascular model with tube voltage at 120kv,100kV and 80kV,and with ATCM(Noise index:10;Tube current scope:100 mA-the highest value of the equipment allowed),and with scanning parameters that to be using in the examination of intracranial and cervical arteries CTA.Compare and analyze the CT value in the vascular model and noise between images of each group,and compare the radiation dose between each group.2.60 cases of patient whose station of illness need them to conduct intracranial and cervical arteries CTA were collected randomly.And they were divided into A,B and C three groups randomly,each group was 20 cases.Performing intracranial and cervical arteries CTA using 120KV,100KVand 80KV respectively,and coordinating with automatic tube current modulation technique and 50%Adaptive Statistical Iterative Reconstruction preset.Reconstruct the data information archived by examination with VR,MIP and MPR reconstruction technology,and compare the CT value in the intracranial and cervical arteries and evaluate the quality of the images and radiation dose.3.The"group C" in "Part two" was considered as the "group A" in "part three";another 40 cases of patients were collected randomly,and they were divided into group B and C randomly,each group was 20 cases.Using 370 mgl/ml,350 mgI/ml and 320 mgI/ml contrast media respectively to conduct intracranial and cervical arteries CTA with 80KV tube voltage.The rest parameters and methods are the same in the "Part two".Compare the CT value in the intracranial and cervical arteries and the quality of the images dose.Results:1.The CT value within the vascular models rise with the drop of tube voltage,and it is negatively correlate highly with the drop of tube voltage(r =-0.93);the 100KV group increased by an average of 24.08%than the 120KV group,the 80KV group increased by an average 27.90%compared to the 120KV group;the CT value in the intracranial and cervical arteries increased 58.47%by average when the tube voltage decrease from 120KV down to 80KV.The CT value in the vascular model decreases with the increasing concentration of contrast media,showed a slight positive correlation(r = 0.29,P = 0),but the CT value of 320mgI/ml CM in 80kV CT group reached an average of 636.65HU,which more than 370mgI/ml CM in 120kv and 100kV groups.In the case of using the ATCM and no limit in the tube current,the radiation dose increases with the decrease of tube voltage.There was no significant difference between the three KV values(F= 0.54,P =0.58).2.The diagnoses of all cases are not affected by quality of images of any case patient;there is no image whose score is less than 3 points.There was no significant difference between them(χ~2 = 1.56,P = 0.49).The CT value of the artery increased with the decrease of the tube voltage,the "r" value in the common carotid artery and Ml segments of sylvian artery were-0.48 and-0.53,respectively,the P value were zero,the correlation was lower than the model experiment,and the correlation was negative.There was no statistical significant difference in the common carotid arteries and the Ml segment of sylvian arteries between each group.The F values were 1.17 and 1.93,respectively;and the P values were 0.32 and 0.15,respectively.The difference of scanning range between three groups no statistical significance(P= 0.49);radiation dose decreased with the tube voltage decreasing,and showed a moderate positive correlation(r = 0.79,P = 0),the ED of the 80kV group reduced 51.88%by an average than the 120kv group.3.The image quality of all the three groups can meet the diagnoses,there is no score of images less than 3 points,and there was no significant difference in each group(χ~2 = 0.25,P =0.88).Arterial CT value decreased with the decreasing of contrast media concentration,but the correlation was not obvious,the "r" value in the level of common carotid artery and M1 segment of middle cerebral artery were 0.13 and 0.28,respectively;LSD-t analysis showed that there was no significant difference between the CT value within common carotid arteries and middle cerebral arteries when using different three concentrations of CM(F values between 0.01-0.30,P values were greater than 0.05)。The mean CT value within common carotid arteries and M1 segments of sylvian arteries were 569.35 and 428.75 HU in "320 group",respectively,and they were higher than it were using 120 KV tube voltage and 370 mgI/ml CM.Conclusions:1.Using the ATCM and set a reasonable tube current range to conduct intracranial and cervical arteries CTA,the radiation dose patients received decreased drastically with the decreasing of tube voltage.2.The CT values within vascular filled with iodine contrast medium increasing with the decreased of tube voltage;the image quality of intracranial and cervical arteries CTA using 80KV tube voltage and 370mgI/ml contrast media can meet the clinical requirements.3.Low tube voltage(80KV)combined with low contrast media concentration(320mgI/ml)with ATCM and 50%Adaptive Statistical Iterative Reconstruction in intracranial and cervical arteries CTA examination is feasible,with an image quality that does not affect the diagnosis;it is valuable to reduce the radiation dose and contrast media damage in patients. |
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