中文摘要：

目的探讨管电压和碘对比剂浓度对腹部动态cT增强图像质量的影响。方法采用4种扫描方案，对6只小型猪行腹部动态cT增强扫描。方案1：管电压80kV、对比剂含碘270mg／ml；方案2：管电压120kV、对比剂含碘270mg／ml；方案3：管电压80kv、对比剂含碘370mg／ml；方案4：管电压120kV、对比剂含碘370mg／ml。对方案1和方案3图像行迭代算法（iDose4）重组；方案2和方案4图像行常规滤波反投影（FBP）重组。各方案对比剂碘含量均为600mg／kg，注射碘流率均为0．92g／s（含碘270mg／ml对比剂流率3,4ml／s、含碘370mg／ml流率2．5ml／s）。对各组图像进行主观评价，包括图像质量评分、图像噪声评分、图像锐利度评分；进行客观评价，测量主动脉、门静脉、肝静脉、下腔静脉及肝实质的强化CT值、噪声、达峰时间、信噪比（SNR）及对比噪声比（CNR），并记录扫描的CT剂量容积指数（CDTIv01）和剂量长度乘积（OLP）。采用方差分析比较不同扫描方案下各血管和肝实质的强化CT值、噪声、SNR和CNR，采用非参数Kruskal．Wallis检验比较不同扫描方案下各血管和肝实质的达峰时间及图像评分。结果4种方案扫描的主观图像质量、图像噪声和图像锐利度评分均〉3分，差异均无统计学意义（P均〉0．05）。方案1～4扫描的主动脉强化峰值分别为（729±46）、（515±84）、（707±59）、（513±53）HU，下腔静脉强化峰值分别为（366±95）、（282±39）、（368±92）、（262±67）HU，门静脉强化峰值分别为（213±18）、（180±21）、（201±29）、（176±27）HU，肝静脉强化峰值分别为（207±18）、（179±24）、（193±10）、（170±14）HU，肝实质强化峰值分别为（128±7）、（135±5）、（127±4）、（135±6）HU，方案1和方案3、方案2和方案4比较，上述部位强化CT峰值差异均无统计学意义（P均〉0．05），且方案1、方?

英文摘要：

Objective To investigate the effect of tube voltage and iodine concentration of contrast medium （CM） on abdominal dynamic enhanced CT image quality. Methods Six miniature pigs underwent repeated upper abdomen dynamic contrast-enhanced CT scans in 4 scanning protocols with different concentration of CM and tube voltage, namely, protocol 1, CM with iodine concentration of 270 milligrams iodine per milliliter （mg/ml） and 80 kV tube voltage; protocol 2, 270 mg/ml and 120 kV; protocol 3,370 mg/ml and 80 kV and protocol 4, 370 mg/ml and 120 kV. The same iodine dose （600 mg/ml） and iodine delivery rate （IDR） （920 mg/s） were used in all protocols. The CM with iodine concentration of 270 mg/ml were injected at a flow rate of 3.4 ml/s, and 370 mg/ml CM injected at 2.5 ml/s. Image reconstruction was performed with iterative reconstruction （iDose4） in protocol 1 and 3,filtered back projection （FBP） was used in protocol 2 and 4. A subjective scoring system for image quality, image noise and sharpness was conducted by 2 radiologists independently. The measured values （peak of enhanced CT values, image noise of aorta, inferior vena cava, portal vein, hepatic vein and liver parenchyma） as well as the calculated values [their time-to-peak, signal-to-noise （SNR） and contrast-to-noise （CNR） ratios] were compared between among 4 protocols. The CT volume dose index （CDTIvol） and dose length product （DLP） were recorded from the CT console after each scanning. Factorial designed ANOVA was used for comparison of enhanced CT values of vessels and liver parenchyma, noise, SNR and CNR. The Kruskal-Wallis test was used for comparison of values among the 4 protocols, including the time-to-peak enhancement of vessels and liver parenchyma, the subjective scores of image quality indices. Result There was no significant differences in subjective scores of the image quality, image noise and image sharpness （P〉0.05）. The scored were more than 3, and the images with 4 scanning protocols were all