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目的 探讨100kVp条件下使用碘克沙醇(270 mg I/ml)联合iDose4迭代重建技术行下肢动脉CTA检查的可行性.方法 2014年7月1日至2015年1月1日温州医科大学附属第二医院临床拟诊下肢动脉病变而行下肢动脉CTA检查的连续52例患者,分为两组,分别采用不同的CT扫描方案:双低组26例,采用100kVp、碘克沙醇(270 mg I/ml)及iDose4-4迭代算法;常规组26例,采用120 kVp、碘普罗胺(370 mg I/ml)及滤波反投影(FBP)算法.两组使用对比剂的总量均为95 ml.测量并计算L4椎体、髋关节、膝关节及踝关节4个层面动脉CT值、背景噪声、信噪比(SNR)和对比噪声比(CNR),并对图像质量进行主观评价.记录扫描长度(L)、容积CT剂量指数(CTDIVOL)和剂量长度乘积(DLP),并计算有效剂量(ED).对测量结果和主观评价进行统计学分析.CTA结果以数字减影血管造影(DSA)检查为“金标准”进行对比分析.结果 (1)两组受检者性别、年龄、身高、体质量及体质指数差异无统计学意义(P＞0.05).(2)两组图像在L4椎体、髋关节、膝关节及踝关节4个层面动脉CT值、SNR和CNR差异无统计学意义(P＞0.05).双低组较常规组在髋关节及膝关节层面背景噪声分别增加16.6％和13.8％ (P ＜0.05).(3)两组图像质量均符合诊断要求,主观评价的差异无统计学意义(P＞0.05).(4)双低组CTDIvoL、DLP、ED均低于常规组,差异均有统计学意义(均P ＜0.05).双低组使用对比剂的总碘量为25.6 g,常规组为35.2 g.(5)双低组中7例行DSA检查,共发现18处狭窄和闭塞,其中16处与CTA相符;常规组中6例行DSA检查,共发现15处狭窄和闭塞,其中13处与CTA相符.两组诊断效能的差异无统计学意义(P=0.626).结论 100 kVp条件下使用碘克沙醇(270 mg I/ml)联合iDose4迭代重建技术行下肢动脉CTA检查,图像质量能够满足临床诊断需要,同时能降低患者的辐射剂量和对比剂剂量.

Objective To evaluate the feasibility of CT angiography of lower extremities by using 100 kVp as tube voltage and Iodixanol(270 mg I/ml) as contrast medium combined with iDose4 iterative reconstruction technique.Methods A total of 52 continuous patients with clinically suspected lesions of lower extremity arteries underwent CT angiography of lower extremities,divided into 2 groups,and different scan protocols were adopted." double low" group included 26 patients using 100 kVp,Iodixanol (270 mg I/ml) and iDose4-4 iterative reconstruction algorithm;routine group included 26 patients using 120 kVp,Iopromide(370 mg I/ml) and filtered back projection reconstruction algorithm.The total amount of contrast medium in both groups was 95 ml.Artery CT value and background noise at the level of L4 vertebral,hip,knee and ankle were measured,signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated,and the quality of images was evaluated subjectively.Scan length(L),volume CT dose index (CTDIvoL) and dose length product(DLP) were recorded,and the effective dose(ED) was calculated.The measurement results and subjective evaluation were analyzed statistically.CTA results were analyzed with the digital subtraction angiography (DSA) as the "gold standard".Results (1) No significant difference was existed in gender,age,height,weight and body mass index(BMI) of these two groups(P ＞0.05).(2)No significant difference was existed in artery CT value,SNR and CNR at the level of L4 vertebral,hip,knee and ankle of the two groups (P ＞ 0.05).Compared with routine group,background noise of "double low" group at the level of hip and knee increased by 16.6％ and 13.8％,respectively(P ＜0.05).(3)The image quality of the two groups met the requirement of diagnosis,no significant statistical difference was existed in subjective evaluation(P ＞ 0.05).(4) The CTDIVOL,DLP,ED of "double low" group were lower than that of routine group,with significant statistical difference(P ＜ 0.05).The total amount of iodine in "double group" was lower than that of routine group(25.6 g vs 35.2 g).(5)A total of 7 cases from "double low" group underwent DSA examination,and 18 pathological changes (stenosis and occlusion) were found totally,in which 16 matched CTA;6 cases from routine group underwent DSA examination,and 15 pathological changes (stenosis and occlusion) were found totally,in which 13 matched CTA.No significant statistical difference was existed between the two groups in diagnostic efficacy (P =0.626).Conclusions Using 100 kVp and Iodixanol (270 mg I/ml) combined with iDose4-4 iterative reconstruction technique for CT angiography of lower extremities,the image quality could meet the requirement for clinical diagnosis,the radiation dose and the volume of contrast medium could be lowered.