腹主动脉CT血管成像的低剂量对比剂应用研究

目的 探讨腹主动脉CTA低剂量对比剂成像的可行性.方法 将98例行腹主动脉CTA检查的患者按照对比剂剂量和注射流率的不同随机分为3组,均采用碘海醇(350 mgI/ml),A组34例,对比剂用量为90ml,生理盐水20ml,注射流率4 ml/s;另外64例对比剂剂量和流率按照公式注射流率=患者体质量×对比剂剂量和体质量的比值/(5+曝光扫描时间)计算获得,每组32例,B组和C组对比剂剂量和体质量的比值分别为0.8～0.9和0.6～0.7 ml/kg.根据原始图像和MIP像评价腹主动脉及其分支、肾动脉及其分支图像质量,并测量血管内的对比剂浓度,采用单因素方差分析比较各组腹主动脉及其分支的CT值,采用x2检验比较肾动脉及其分支的评分.结果 3组中腹主动脉、腹腔干、肾动脉、脾动脉和肠系膜上动脉均清晰显示,3组腹主动脉内CT值分别为(363 ±28)、(362 ±28)和(334±14) HU,腹腔干内CT值分别为(368±28)、(367±28)和(338±15)HU,肾动脉内CT值分别为(365±27)、(364 ±29)和(336±15) HU,脾动脉内CT值分别为(373±28)、(372 ±28)和(343±15)HU,肠系膜上动脉内CT值分别为(374±28)、(372±28)和(344±16)HU,3组间上述血管内CT值差异均有统计学意义(P值均为0.000),两两比较,A组和C组、B组和C组间各血管内CT值差异有统计学意义(P值均＜0.01),A组和B组间各血管内CT值差异无统计学意义(P值均＞0.05).A组每例患者对比剂用量为90ml,B组和C组每例患者人均对比剂用量分别为(51±9)和(40±9)ml,差异有统计学意义(F=537.091,P=0.000),两两比较差异均有统计学意义(P=0.000).A组肾动脉图像质量优秀、良好和一般的为26、7和1例,B组分别为24、7和1例,C组分别为22、8和2例,差异无统计学意义(x2 =0.561,P=0.755).结论 腹主动脉CT血管成像个体化注射方式在满足临床诊断的需要下最大程度的减少了对比剂的用量.

Study on the feasibility of abdominal aortic CT angiography with low dose contrast medium

Objective To study the feasibility of abdominal aortic CT angiography with low dose contrast medium.Methods The patients who took the examinations were divided into three groups.In 34 patients of group A,the injection flow rate was 4 ml/s,and the contrast medium volume was 90 ml and 20 ml of saline was applied.The contrast medium dose and injection flow rate of the other 64 patients were determined according to the formula,injection tlow rate = patients' body mass × ratio of contrast medium dose to the body mass / (5 + exposure time).In B and C group with 32 cases each,the ratio of contrast medium dose to body mass were 0.8 to 0.9 and 0.6 to 0.7 ml/kg.The depiction and the measured intraarterial concentration of contrast medium of the abdominal aorta and the renal arteries as well as their branches were compared and evaluated on the source images and MIP images generated among three groups respectively.CT values of the abdominal aorta and its branches in each group were analyzed using singlefactor analysis of variance,while renal artery and its branches were analyzed using x2 test score.Results The abdominal aorta,the celiac trunk,the splenic artery,the superior mesenteric artery,the renal arteries and their branches were all well shown in three groups.The CT value within the abdominal aorta were (363 ±28),(362 ±28) and (334 ± 14) HU for the three groups respectively,the CT values within the celiac were (368 ±28),(367 ±28) and (338 ± 15)HU,the CT value within the renal artery were (365 ±27),(364 ± 29) and (336 ± 15) HU respectively,the CT value within the splenic artery were (373 ±28),(372 ± 28) and (343 ± 15) HU respectively,and the CT value within the superior mesenteric artery were ( 374 ± 28 ),( 372 ± 28 ) and ( 344 ± 16 ) HU respectively.There were significant differences among the three groups ( P = 0.000).There were significant differences between A group and C group,B group and C group ( P ＜ 0.01 ),while no significant difference existed between A group and B group( P ＞0.05 ).The amount of contrast agent for each patient in group A was 90 ml,while the amount of contrast agent in group B and C was (51 ± 9) and (40 ± 9) ml respectively.There were significant differences of the contrast medium volume among the three groups ( F = 537.091,P = 0.000).Results of pairwise comparisons were statistically significant(P =0.000).Image quality of renal artery in group A was rated as excellent,good,and generally for 26,7 and 1 cases,24,7 and 1 for group B,and 22,8 and 2 for group C.There were no significant differences in image quality of the renal arteries among the three groups ( x2 = 0.561,P = 0.755 ).Conclusion The individualization of injection method in abdominal aortic CT angiography can minimize the amount of contrast agent but to meet the clinical requirements.