【作者】 王道才；

【导师】 王锡明；

【作者基本信息】 山东大学 ， 影像医学与核医学（专业学位）， 2014， 博士

【摘要】 一、MSCT低管电压扫描对比剂剂量优化的实验研究目的：探讨与低管电压(kVp) CT扫描技术匹配的对比剂剂量。材料方法：配制不同对比剂含量的混合溶液(对比剂和生理盐水,单位ml,对比剂为碘海醇300mgI/ml),分别装入5只试管内,0号试管对比剂含量为2%,1-4号管对比剂含量依次较0号试管减少10%,20%,30%,40%,分别为1.8%、1.6%、1.4%、1.2%,再装入标准腹部体膜小孔内,分别行90kVp和120kVp腹部条件扫描,分别测量5只试管内对比剂溶液的CT值,比较不同对比剂含量溶液90kVp管电压时的CT值,以及90kVp各不同对比剂含量溶液的CT值与120kVp0试管对比剂溶液CT值的差异,进行统计学分析。结果：90kVp条件下,0-4号试管的CT值随着对比剂剂量的减少而降低,0和1号试管内对比剂溶液的CT值无统计学意义,0、1与2、3、4号试管间对比剂溶液CT值有统计学意义。90kVp条件下,0、1、2号试管内对比剂溶液的CT值均高于120kVp的0号管,90kVp条件下的3、4号管(即对比剂剂量减少30-40%)对比剂溶液CT值与120kVp的0号管对比剂溶液CT值间无统计学差异,但辐射剂量降低约33%。结论：低管电压扫描时减少30-40%的对比剂剂量,可以达到常规扫描模式的强化效果,同时辐射剂量降低33%。二、MSCT低管电压扫描门静脉成像延迟时间的选择目的：探讨MSCT90kVp门静脉成像延迟时间的选择。材料方法：46例行腹部CT强化扫描的患者,随机分为A、B两组,每组23例,均行9OkVp.395mAs腹部扫描,对比剂为碘海醇300mgI/ml,注射剂量为1.2ml/kg,速率3.0ml/s,行门脉期扫描时延迟时间分别为A组50s,B组60s,选取门脉期图像进行分析,分别测量肝实质及门静脉CT值,比较A、B两组患者肝实质CT值、门静脉CT值及不同延迟时间肝实质和门静脉CT值差值,进行统计分析。结果：A组门静脉平均CT值为197.2±27.2Hu,B组为178.3±24.0Hu,A组高于B组,二者有统计学差异；A组肝实质平均CT值为109.8±15.3Hu,B组肝实质平均CT值为108.4±12.9Hu,二者无统计学差异；A、B两组门静脉与肝实质的差值分别为87.4±23.8Hu,69.9±30.8Hu,A组高于B组,二者差异有统计学意义。结论：90kVp低管电压腹部CT扫描,门静脉成像延迟时间50s强化效果优于60s。异；ED分别为3.8±O.4mSv,5.7±0.5mSv,二者有统计学差异,90kVp组辐射剂量减少了33%。结论：MSCT双低扫描可用于正常体质量指数患者的门静脉成像,且门静脉显示优于常规扫描,同时降低了辐射剂量,减少了对比剂用量。更多还原

【Abstract】 PART I Experimental study about optimization of contrast agent dose with low tube voltage MSCT scanningObjective:To investigate the feasibility of reducing contrast agent dose with low tube voltage (kVp) high tube current (mAs) CT technical. Materials and methods: Preparation of five different contrast agent solution volume ratio (contrast agents and saline)2%;1.8%;1.6%;1.4%;1.2%, numbered0,1,2,3,4.10%,20%,30%,40%of the contrast media dosage were reduced from1to4, and then put them into the standard abdominal phantom. The tube that contained highest concentration was scanned by120kVp200mAs with abdomen scanning mode. All the5tubes were scanned by90kVp,395mAs with abdomen scanning mode. Comparing the CT values of the different tubes between the two scanning mode. SPSS19.0was used for statistical analysis. Results:If the volume of contrast agent reduced less than20%the measurement value by90kVP CT scanning mode is higher than the maximum concentration values by the conventional CT scanning. The contrast agents reduced by30%that there is no difference between the two scanning style. If the contrast agent reduced by40%the CT value of90kVP scan mode was lower than conventional scanning measurement. The radiation dose was reduced by approximately33%. Conclusion:The contrast agent dose was reduced by30-40%which had no significant effect on the CT values by the low kVp scanning technology. PART Ⅱ Optimal delay time for portography at90kVp MSCTObjective:To investigate the optimal delay time by90kVp MSCT scanning technology in the portography. Materials and Methods:MSCT scanning were performed in two groups (A, B) and there were23cases in each group.90kVp,395mAs abdominal scanning mode was used. The delay time was50s in group A and60s in group B. The portal venous phase images were analyzed. CT values of the liver parenchyma and the portal vein were measured and the CT values of hepatic parenchyma, portal vein and CT value difference between hepatic parenchyma and portal vein were compared within group A and B. Results:The portal vein CT values of group A were higher than the corresponding values in group B. The liver parenchyma CT values within two groups were not statistically significant. Comparing the difference between the portal vein and liver parenchyma was statistically significant. The value in group A is higher than that in group B. Conclusion:Portography delay time by90kVp abdominal scanning mode50s is better. PART Ⅲ Clinical application of low tube voltage and low dosage contrast agent on CT portographyObjective:The purpose of this study was to investigate feasibility of the low dose CT scanning on portography with normal body mass index (BMI) in patients. Materials and Methods:Portography was performed with two protocols:low kVp, high mAs CT scanning (90kVp,395mAs) with the contrast material volume1.2ml/kg and normal CT scanning (120kVp,200mAs) with the contrast material volume1.5ml/kg. For each protocol there were59cases. The body mass index (BMI) of each protocol was less than25kg/m2. Portal phase CT scans were acquired50s after contrast material injection. CT attenuation (HU+SD) was measured at liver and portal vein. The noise(SD) of image was measured at abdominal aorta at the level of main portal vein, then calculated signal to noise ratio (SNR), contrast to noise ratio (CNR), and effective dose(ED) with each protocol were assessed according to dose-length product (DLP).The image quality was evaluated by two radiologists. The SNR, CNR, ED and image quality were compared and differences were examined for significance by using SPSS (version19.0). P<0.05was considered to indicate a significant difference. The image score conformance according to2physicians was analyzed by Kappa consistency. Results:CNR, SNR were better at90kVp than120kVp images (p<0.05). SD was no significant difference between the two protocols (p>0.05). At90kVp versus120kVp, the ED reduction was33%and there was difference in image quality score between the two protocols, the images at90kVp superior to120kVp (p<0.05). The average amount of contrast agent decreased17.8%. Conclusion:Low dose CT technique in patients with normal BMI, the portography is superior to conventional scanning, while reducing the radiation dose and the amount of contrast agent. PART I Experimental study about optimization of contrast agent dose with low tube voltage MSCT scanningObjective:To investigate the feasibility of reducing contrast agent dose with low tube voltage (kVp) high tube current (mAs) CT technical. Materials and methods: Preparation of five different contrast agent solution volume ratio (contrast agents and saline)2%;1.8%;1.6%;1.4%;1.2%, numbered0,1,2,3,4.10%,20%,30%,40%of the dosage of contrast media were reduced from1to4, and then put them into the standard abdominal phantom. The tube that contained highest concentration was scanned by120kVp200mAs with abdomen scanning mode. All the5tubes were scanned by90kVp,395mAs with abdomen scanning mode. Comparing the CT values of the different tubes between the two scanning mode. SPSS19.0was used for statistical analysis.Results:If the volume of contrast agent reduced less than20%the measurement value by90kVP CT scanning mode is higher than the maximum concentration values by the conventional CT scanning. The contrast agents reduced by30%that there is no difference between the two scanning style. If the contrast agent reduced by40%the CT value of90kVP scan mode was lower than conventional scanning measurement. The radiation dose was reduced by approximately33%. Conclusion:The contrast agent dose was reduced by30-40%which had no significant effect on the CT values by the low kVp scanning technology. PART Ⅱ Optimal delay time for portography at90kVp MSCT Objective:To investigate the optimal delay time by90kVp MSCT scanning technology in the portography. Materials and Methods:MSCT scanning were performed in two groups (A, B) and there were23cases in each group.90kVp,395mAs abdominal scanning mode was used. The delay time was50s in group A and60s in group B. The portal venous phase images were analyzed. CT values of the liver parenchyma and the portal vein were measured and the CT values of hepatic parenchyma, portal vein and CT value difference between hepatic parenchyma and portal vein were compared within group A and B. Results:The portal vein CT values of group A were higher than the corresponding values in group B. The liver parenchyma CT values within two groups were not statistically significant. Comparing the difference between the portal vein and liver parenchyma was statistically significant. The value in group A is higher than that in group B. Conclusion:Portography delay time by90kVp abdominal scanning mode50s is better. PART Ⅲ Clinical application of low tube voltage and low dosage contrast agent in MSCT portographyObjective:The purpose of this study was to investigate feasibility of the low dose CT scanning on portography with normal body mass index (BMI) in patients. Materials andMethods:Portography was performed with two protocols:low kVp, high mAs CT scanning (90kVp,395mAs) with the contrast material volume1.2ml/kg and normal CT scanning (120kVp,200mAs) with the contrast material volume1.5ml/kg. For each protocol there were59cases. The body mass index (BMI) of each protocol was less than25kg/m2. Portal phase CT scans were acquired50s after contrast material injection. CT attenuation (HU±SD) was measured at liver and portal vein. The noise(SD) of image was measured at abdominal aorta at the level of main portal vein, then calculated signal to noise ratio (SNR), contrast to noise ratio (CNR), and effective dose(ED) with each protocol were assessed according to dose-length product (DLP).The image quality was evaluated by two radiologists. The SNR, CNR, ED and image quality were compared and differences were examined for significance by using SPSS (version19.0). P<0.05was considered to indicate a significant difference. The image score conformance according to 2physicians was analyzed by Kappa consistency. Results:CNR, SNR were better at90kVp than120kVp images (p<0.05). SD was no significant difference between the two protocols (p>0.05). At90kVp versus120kVp, the ED reduction was33%and there was difference in image quality score between the two protocols, the images at90kVp superior to120kVp (p<0.05). The average amount of contrast agent decreased17.8%. Conclusion:Low dose CT technique in patients with normal BMI, the portography is superior to conventional scanning, while reducing the radiation dose and the amount of contrast agent.更多还原