Clinical Study On Coronary CT Angiography Using100kVp And270mg I／mL Iodixanol With Adaptive Statistical Iterative Reconstruction (ASIR)

Objective(1) To compare the diagnostic efficiency between different contrast mediumconcentrations in Coronary CT angiography(CCTA)，and to evaluate the clinicalfeasibility of100kVp and270mgI／mL iodixanol in CCTA with64slice spiral CTscanner using ASIR reconstruction．(2) To compare the image quality of different percentage ASIR using100kVp and270mgI／mL iodixanol in CCTA with64slice spiral CT scanner.Materials and methods(1) Cases collection:90patients whose BMI from20to25kg/m2with suspected coronary diseaseunderwent coronary CT angiography in the general hospital of Shenyang militarycommand from March.2013to August.2013.(2) Instruments and machines:GE64-slice gemstone CT scanner(GE Discovery750HD，GE Healthcare，Milwaukee，USA)，GE AW4.5workstation，Medrad Stellant CT injection system.(3) Coronary CT angiography imaging techniqueAn oral β-blocker (50-100mg) was administered45-60minutes before CT scan.Also，0.5mg of sublingual nitroglycerine spray was administered2-4minutes beforecardiac CT，unless contraindicated. The breathless training was performed by technician before the check and tried to keep the same level movement of the chest wall. Takingsupine position when the check was performed and connecting the electrocardiographic.Use the GE HD750gemstone CT scanner made in USA，Firstly，chest AP and LATscan was performed in order to determine the range of heart. After scanning the series ofthe calcification score，injected different contrast media according to different group.Coronary CT angiography scanning parameters and group information shown asfollows:Group1(double low group)，100kVp，600mA，contrast media: Visopaque270mgI/ml. Group2（low radiation group），100kVp，600mA，contrast media: Xenetix350mgI/ml)，Group3（normal group）:120kVp，600mA，contrast media：Xenetix350mgI/ml). Group3were reconstructed using filtered back projection (FBP)，the othertwo were reconstructed using30%ASIR.Group1were also reconstructed with differentpercentage of ASIR(0%、20%、40%、60%、80%、100%).(4) Coronary CT angiography image analysis and post-processing methodCT image data were transfer to AW4.5workstation， coronary artery werereconstructed with VR(volume rendering，VR)，coronary artery tree and CPR(curveplanar reconstruction，CPR)．Subjective evaluation was assessed by two experiencedradiologist by5-point scale and omitted the case ranged below3-point. According to thecoronary segment standard made by AHA(American Heart Association，AHA)，CTattenuation of proximal ascending aorta and the main segments of coronary arteries(S1、S5、S6、S11、S12)were measured. Objective evaluation of the image quality(Noise，CNR，SNR)were estimated. The ED（Effective radiation Dose，ED）and SSDE（SizeSpecific Dose Estimate，SSDE）of each patient were calculated．A comparison ofpatients’ comfort was recorded.(5) Statistical MethodsStatistical analysis was performed by using statistical software (SPSS for Windows，version19.0，IBM，USA). The presentation of patient’s age，BMI，coronary arteryCT value， radiation dose and objective evaluation of the image quality were x±S， ANOVA for the group comparison. The Mann-Whitney U test and The Kruskal-Wallistest was used for categorical data.A comparison of patient comfort between theiodixanol group(group1) with Iobitridol group(group2，group3) with χ2test. A p value ofless than0.05was considered to indicate statistically significant difference.RESULTS(1) The mean CT attenuation of the measured vessels in each group all meets the clinicdiagnosis needs. All vessels imaging quality score ranged above3-points.The ED indouble low group which were obviously lower than that in normal prospectiveEGG-gated group (p<0.05)，with about38.5%of reduction．As for the SSDE，thereduction was36．4%(p<0.05)．Measured image noise，calculated SNR and CNR wereno statistically significant difference between each group (p＞0.05).The mean CTattenuation of the measured vessels in group2were higher than the other groups withstatistically significant difference (p＜0.05). The patient in iodixanol group feel morecomfort than in Iobitridol group (p＜0.05).(2) In comparison with FBP (0%ASIR)，the use of20%，40%，60%，80%，and100%ASIR resulted in reduced image noise between groups (12%，24%，33%，46%，and51%，respectively；p <0.001) without difference in the mean CT attenuation of themeasured vessels (p=0.60). ASIR also increased SNR、CNR between groups(7%，22%，50%，81%，103%and8%，23%，50%，81%，101%，respectively；p <0.001)，There were significant differences between groups (0%，20%，40%，60%，80%，and100%ASIR) in the subjective scores (1.5，1.9，3.9，4.0，2.0，and1.2，respectively；p <0.001).Reconstruction using40%and60%ASIR had the highest the subjectivescores，display the best imaging quality for coronary artery.CONCLUSIONS（1） To those whose body mass index between20～25kg/m2，CCTA performed by100KVP and270mgI/ml iodixanol with prospective EGG-gated may obtain the imagequality to meet diagnostic needs with a large scale reduction of the radiationdose．270mgI/ml iodixanol also can promote patients’ comfort during the course of examination.（2） In comparison with FBP，reconstruction using40%and60%ASIR had thehighest subjective scores of imaging quality in CCTA.