“双低”技术在胸部CT增强扫描中的可行性研究

The feasibility of CT low tube voltage combined with low concentration contrast agent in enhanced imaging of the chest

目的 :探讨CT"双低"技术(等渗低浓度对比剂、低管电压)对胸部增强扫描成像质量及辐射剂量的影响。方法 :选取85例行CT胸部平扫及增强扫描的初诊患者(18.5 kg/m2<体质量指数<28 kg/m2),随机分为A组(41例)和B组(44例)。A组采用高浓度对比剂(350 mg I/m L)、常规管电压(120 k V);B组采用等渗低浓度对比剂(270 mg I/m L)、低管电压(100 k V)。分别记录及计算每位患者的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED)、血管及肌肉强化后的平均CT值、噪声及对比噪声比(CNR)。图像质量客观评价通过对各组血管及肌肉强化后的CT值、CNR分析得出;图像质量主观评价由2名不同年资诊断医师采用4分制对各组图像质量进行评分。各组间辐射剂量指标、客观评价指标及主观图像质量评价均采用t检验,以P<0.05为差异有统计学意义。结果:B组较A组平均CTDIvol降低36.87%,平均DLP值降低36.19%,平均ED值降低36.35%(均P<0.05)。A、B组强化后血管平均CT值、肌肉平均CT值差异均无统计学意义(均P<0.05),B组噪声较A组增加约28.3%,CNR降低约22.0%,差异均有统计学意义(均P<0.05),A、B组主观图像质量评分差异无统计学意义(P>0.05)。结论:使用"双低"技术行胸部CT增强扫描,可有效降低受检者辐射剂量,降低对比剂肾病及过敏风险,并能满足影像诊断需求,具有一定的可行性。

Objective：To explore the feasibility of CT low tube voltage combined with low concentration contrast agent in enhanced imaging of the chest. Methods：85 patients with chest enhanced CT scan were randomly divided into 2 groups. Group A（28 males,13 females） were performed with conventional k V and high concentration contrast agent（120 k V,350 mg/m L）,group B（30 males,14 females） were performed with low k V and low concentration contrast agent（100 k V,270 mg/m L）. The CTDIvol,DLP,ED,the average enhanced CT values of vessels and muscles,image noise,CNR and the subjective image quality in two groups were recorded and compared. Results：Comparing with group A,the average CTDIvol of group B decreased 36.87%,the average DLP decreased 36.19%,the average ED decreased 36.35%,the average SD increased 28.3%,the average CNR decreased22%. The average blood CT value and muscle CT value between two groups had no significant differences. Subjective image quality scores in two groups had no statistically significant difference. Conclusions：CT low tube voltage combined with low concentration contrast agent in enhanced imaging of the chest can decrease the radiation dose of patient,and reach the requirements of clinical diagnosis,and can be used in enhanced chest CT.