Objective:The purpose of the present study was to investigate the image quality of low radiation dose abdominal CT scan using gemstone spectral imaging (GSI) and adaptive statistical iterative reconstruction technique (ASIR).Methods:90 patients were enrolled and underwent both plain and dual-phase enhanced abdominal CT scan using GE Discovery 750HD 64-row CT scanner.In experiment group A (30 cases),GSI (60keV and 50％ ASIR) with 450mg I/kg contrast material was administrated;in experiment group B (30 cases),conventional scan mode (120kVp) with 300mg I/kg contrast material was used;in control group C (30 cases),conventional scan mode (120kVp) with 450mg I/kg contrast material was dministrated.In each group,CT values of 26 ROIs including abdominal vessels [arterial-phase (AP) or portal-phase (PP)] and organs,muscles and fat tissue (in three phases) were obtained.The corresponding signal-to-noise ratios (SNRs) were calculated and image quality were subjectively evaluated using five point Likert scale.Results:There were no significant differences in age,height,weight and BMI among the three groups (P＞0.05).The CT values of 26 ROIs in group A were higher than those in group C.Statistical differences were existed in the CT values of 23 ROIs between the two groups (P＜ 0.05) except three ROIs of liver on plain and AP images and muscles on plain images.The CT value of each ROI in group B was less than that in group C,but no significant difference was showed (P＜0.05).The SNRs of 25 ROIs (except SMA) in group A were higher than those in group C,no statistical difference was showed only in the SNRs of left portal vein,liver and spleen in AP,pancreas in plain and PP (P＜0.05);and the SNRs in group B were less than those in group C but with no significant difference (P＞0.05).As for subjective evaluation,there was no significant difference of image quality scores among the three groups (P＞0.05).The dose-length product (DLP) in group A was less than that in group C with significant difference (P＜0.001),and the contrast medium dose in group B was less than that in group C with significant difference (P＜0.001).Conclusion:With the help of ASIR and GSI,abdominal CT scan using low tube voltage can get high quality images.%目的:探讨在腹部低剂量CT扫描中使用宝石能谱单能量成像(GSI)结合自适应统计迭代重建技术的成像质量.方法:90例患者使用GE Discovery CT750 HD 64排CT机行腹部CT平扫及双期增强扫描.实验组A(30例)采用GSI技术(60 keV+ASIR 50％)+对比剂碘剂量450 mg I/kg;实验组B(30例)采用常规扫描(120 kVp)十对比剂碘剂量300 mg I/kg;对照组(30例)行常规扫描(120 kVp)+对比剂碘剂量450 mg I/kg.每组均测量腹部大血管(动脉期/静脉期)、脏器和肌肉(三期)共26个ROI的CT值并计算相应的SNR,使用5分法(Likert分级)对各部位的图像质量进行主观评价.结果:三组患者的年龄、身高、体重及身体质量指数(BMI)间的差异均无统计学意义(P＞0.05).A组中26个ROI的CT值均高于对照组,除平扫和动脉期肝脏CT值和平扫肌肉CT值外,其它23个ROI的CT值在两组间的差异均有统计学意义(P＜0.05).B组各ROI的CT值均低于对照组,但差异无统计学意义(P＞0.05).A组中(除SMA外)各ROI的SNR均高于对照组,仅门脉左支、动脉期肝和脾、平扫和静脉期胰腺的SNR在两组间的差异无统计学意义(P＞0.05).B组的SNR均低于对照组,但差异无统计学意义(P＞0.05).主观评价方面,三组间图像质量评分的差异无统计学意义(P＞0.05).A组与对照组间辐射剂量的差异有统计学意义(P＜0.001);B组对比剂剂量与对照组间的差异有统计学意义(P＜0.001).结论:在能谱CT成像结合ASIR技术的帮助下,使用低管电压能得到较好的腹部CT图像质量.
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