摘要
目的探讨多层螺旋CT肺动脉成像（CTPA）低辐射剂量与低对比剂量成像的可行性。方法搜集258例临床拟诊肺栓塞患者,挑选体质量指数（BMI）〈22.5的患者90例行CTPA。按照管电压及对比剂剂量的不同随机分成3组,均采用碘海醇（350 mg I/ml）。Ⅰ组30例,管电压80 k V,对比剂40 ml,图像重建算法为正弦确认迭代重建算法（SAFIRE）;Ⅱ组30例,管电压100 k V,对比剂40 ml,图像重建算法为滤过反投影重建法;Ⅲ组30例,管电压80 k V,对比剂60 ml,图像重建算法为SAFIRE。90例中63例经CTPA诊断为肺栓塞,分别测量3组肺动脉1~3级分支、栓子及背部肌肉的CT值,并计算信噪比（SNR）及对比噪声比（CNR）。应用独立样本t检验分别比较Ⅰ组和Ⅱ组,Ⅰ组和Ⅲ组的SNR及CNR值差异是否有统计学意义,同时比较Ⅰ组与Ⅱ组的有效辐射剂量（ED）及Ⅰ组与Ⅲ组的对比剂用量。利用Kappa检验分析两位医师分析各组CTPA图像质量的一致性。结果Ⅰ组肺动脉1-3级分支SNR及CNR值分别为9.3±1.3、8.2±2.3、8.5±4.3;8.4±1.4、7.0±2.7、6.8±4.8。Ⅱ组肺动脉1-3级分支SNR及CNR值分别为9.7±3.3、8.5±3.9、8.8±2.9;8.7±3.8、7.3±2.1、7.3±4.0。Ⅲ组肺动脉1-3级分支SNR及CNR值分别为9.1±2.1、8.3±2.0、8.7±5.3;8.2±3.2、7.2±3.3、7.1±5.2。Ⅰ组和Ⅱ组、Ⅰ组和Ⅲ组的SNR及CNR值差异无统计学意义（P〉0.01）。Ⅰ组较Ⅱ组的辐射剂量减少46%,Ⅰ组较Ⅲ组对比剂摄入量下降33%。3组CTPA图像质量差异无统计学意义（P〉0.01）。63例CTPA诊断为肺栓塞患者定量分析显示,3组栓子SNR及CNR值分别为1.1±0.3、8.1±3.6;1.3±0.5、7.7±2.8;1.4±0.3、7.9±2.1,3组SNR及CNR比较差异无明显统计学意义（P〉0.05）。两名医师的评价结果经Kappa检验,各组图像质量分析的一致性较好（P〈0.01）。结论在BMI〈22.5的患者中,可以使用管电压80 k V,对比剂40 ml,图像重建算法为SAFIRE的低辐射剂量与低对比剂量方式扫描方式行CTPA,在满足临床诊断的需要下最大程度的减少了辐射剂量及对比剂的用量。
Objective To evaluate the feasibility of using low radiation dose and low contrast dose to perform CT pulmonary angiography （CTPA）. Methods A total of 90 patients, whose BMI was 〈 22.5, were selected from 258 patients with suspected pulmonary embolism. The patients were equally and randomly divided into 3 groups with 30 cases in each group. CTPA was carried out in all patients. In group A, tube voltage of 80 kV and iohexol （350mgI/ml） of 40 ml were used and SAFIRE reconstruction of image was employed; in group B, tube voltage of 100 kV and iohexol （350mgI/ml） of 40 ml were adopted and FBP reconstruction of image was used ; in group C, tube vohage of 80 kV and iohexol （ 350mgI/ ml） of 60 ml were used and SAFIRE reconstruction of image was employed. Among the 90 patients, pulmonary embolism confirmed by CTPA was found in 63. CT values of grade I to III branches of pulmonary artery, thrombus and back muscles were determined, and the signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） were calculated. Using independent-sample t test, the differences in SNR and CNR were compared between group A and group B as well as between group A and group C; at the same time the mean effective dose （ED） was compared between group A and group B, and the used dose of contrast was compared between group A and group C. The inter-reader agreement of image quality was assessed by Kappa test. Results In group A, the SNR and CNR values of grade Ⅰ to Ⅲ branches of pulmonary artery were 9.3 ±1.3, 8.2 ± 2.3, 8.5 ±4.3 and 8.4 ± 1.4, 7.0 ± 2.7, 6.8 ±4.8 respectively ; those in group B were 9.7 ± 3.3, 8.5 ±3.9, 8.8 ± 2.9 and 8.7 ± 3.8, 7.3 ± 2.1, 7.3 ± 4. 0 respectively; while those in group C were 9.1± 2.1, 8.3 ± 2.0, 8.7 ± 5.3 and 8.2 ± 3.2, 7.2 ± 3.3, 7.1± 5.2 respectively. No statistically significant differences in SNR and CNR values existed between group A and B as well as between group A and C （P 〉 0. 05）. Compared with group B, the radiation dose in group A was reduced by 46% ; and compared with group C, the used dose of contrast agent in group A was decreased by 33%. The differences in image quality among the three groups was not statistically significant （P 〉0.05）. Quantitative analysis of 63 patients with CTPA-proved pulmonary embolism indicated that the SNR and CNR values of thrombus in group A, B and C were 1.1 ± 0.3,8.1 ± 3.6 ; 1.3 ± 0.5, 7.7 ± 2.8 ; 1.4 ±0.3,7.9 ±2.1 respectively, but the differences among the three groups were not statistically significant （ P 〉 0. 05 ）. Kappa coefficient analysis showed that the consistency in evaluating image quality between two radiologists was excellent （P 〈 0.01 ）. Conclusion For patients whose BMI is 〈 22.5, tube voltage of 80 kV and iohexol （350mgI/ml） of 40 ml can be used in CT pulmonary angiography with SAFIRE reconstruction of image, this technique can reduce the overall radiation dose and minimize the amount of contrast agent to the greatest possible advantage while the image quality can meet the diagnostic requirement.
出处
《临床放射学杂志》
CSCD
北大核心
2014年第12期1935-1939,共5页
Journal of Clinical Radiology
