半量对比剂能谱单能量成像在肾动脉CTA中的可行性研究

A feasibility study of half-dose contrast agent with dual-energy spectral CT in renal artery CTA:compared with conventional 120 kV

目的:探讨半量对比剂能谱单能量成像在肾动脉成像中的可行性。方法:收集行肾动脉CTA的患者41例,随机分为对照组(A组)21例和研究组(B组)20例。A组采用常规扫描,120 kV,对比剂用量600 mgI/kg体质量。B组采用能谱扫描,140和80 kV瞬时切换,对比剂用量300 mgI/kg体质量。A组重建1.25 mm、滤波反投影(FBP)图像,B组分别重建40、45、50、55、60、65、70 keV单能量、层厚为1.25 mm、40%ASIR单能量图像。将所有图像行MPR、VR、CPR,比较2组图像质量主观评分,并应用Kappa检验比较2名医师主观评价的一致性。计算肾动脉的SNR、CNR,对2组图像的CT值、SD值、SNR、CNR进行统计学分析。结果:2组一般资料和辐射剂量相比差异均无统计学意义(均P> 0.05)。B组比A组对比剂用量降低了51.6%(P=0.000);B组55 keV时的CT值与A组等效,55、60 keV的SD值与A组最接近,55 keV的SNR与A组最接近,50-65 keV的CNR与A组最接近。结论:在能谱CT单能量肾动脉成像中,半量对比剂55-60 keV的能量点接近常规剂量的图像质量。

Objective:To explore the feasibility of half-dose contrast agent with dual-energy spectral CT in renal artery imaging when compared with conventional 120 k V. Methods:Forty-one patients with renal artery imaging were collected and randomly divided into two groups with Group A as the control group and Group B as the study group. Group A used conventional scan protocol,tube voltage 120 k V,while Groups B used dual-energy spectral imaging mode. The contrast dosages were 600 mg I/kg in Group A and 300 mg I/kg in Group B. The images in Group A were reconstructed at 1.25 mm and FBP while Group B was reconstructed at 40 ke V,45 ke V,50 ke V,55 ke V,60 ke V,65 ke V and 70 ke V,with 40%ASIR images. All the images were reformated with MPR,VR,CPR. The subjective image scores of the two groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the Kappa test. The signal noise ratio(SNR) and contrast noise ratio(CNR) were calculated. The single factor analysis of variance was used to analyze the differences between Group A and 7 subgroups of Group B with P <0.05 being statistically significant. Results:The basic datas and radiation dose between two groups were not significantly different(P> 0.05) while the contrast agent dosage in Group B decreased by 51.6% compared with Group A(P<0.05). The CT value of Group B with was similar to Group A while the SD value of Group B with 55 ke V and 60 ke V monochromatic energy was similar to Group A. The images of Group B with 55 ke V monochromatic energy can obtain the similar SNR with Group A and the CNR of Group B with 50 ke V to 65 ke V monochromatic energy were nearest to that of Group A. Conclusion:In renal artery imaging with spectral CT monochromatic energy,half-dose contrast agent combined with 55 ke V to 60 ke V monochromatic energy images can obtain the similar image quality with that of conventional contrast-agent dose.