超低管电压联合大螺距扫描模式在冠状动脉搭桥术后 随访中的应用

Application value of ultra-low tube voltage combined with large pitch scanning mode in follow-up of patients after coronary artery bypass grafting

目的:探讨超低管电压联合大螺距扫描模式在冠状动脉(冠脉)搭桥术后随访中的应用价值。方法:选取接受冠脉搭桥术并行冠脉CTA(CCTA)的患者54例,随机分为A、B 2组各27例。A组采用超低剂量方案:70 kV,大螺距扫描模式,对比剂注射流率3.0 mL/s,剂量30~40 mL;B组采用常规方案:100 kV,前瞻性心电门控扫描模式,对比剂注射流率5.0 mL/s,剂量50~60 mL。分别在桥血管的近段、中段及远段放置ROI,并记录ROI的CT值和标准差(SD)值,计算SNR和CNR。采用4分法对各节段图像进行主观评分,并计算2组的有效辐射剂量(ED)。结果:2组患者不同节段的桥血管在图像客观质量(包括CT值、SD值、SNR、CNR)及主观质量评分上差异均无统计学意义(均P>0.05)。A组的对比剂剂量、ED分别为(34.9±3.2)mL、(1.1±0.2)mSv,B组分别为(53.4±4.9)mL、(3.2±0.4)mSv,2组差异均有统计学意义(均P<0.05),且A组对比剂剂量和ED较B组分别降低约34.6%和65.6%。结论:心率≤65次/min且心律齐的冠脉搭桥患者,采用70 kV联合大螺距扫描模式可在不降低图像质量的前提下,显著降低对比剂剂量和辐射剂量。

Objective:To investigate the application value of ultra-low tube voltage combined with large pitch scanning mode in the follow-up of patients after coronary artery bypass grafting(CABG).Methods:A total of 54 patients who underwent CABG and coronary CTA(CCTA)were chosen and randomly divided into two groups.For the patients in group A,the ultra-low dose protocol was used,tube voltage of 70 kV,a large pitch scanning mode,the contrast agent rate and dosage of 3.0 mL/s and 30~40 mL.And for the patients in group B,the conventional protocol was used,tube voltage of 100 kV,prospective ECG-gated scanning mode,the contrast agent rate and dosage of 5.0 mL/s and 50~60 mL.The ROIs were placed in the proximal,middle and distal segments of the bridging vessels,and CT value and standard deviation(SD)value were recorded in each ROI,CNR and SNR were calculated.The 4-point scale was used to evaluate image quality,and the effective dosage(ED)was calculated.Results:Both quantitative measures(CT value,SD value,SNR and CNR)and subjective scores for the bridge vessels at various levels between the two groups had no significant differences(all P>0.05).The contrast agent dose and ED in group A[(34.9±3.2)mL and(1.1±0.2)mSv]were lower than those in group B[(53.4±4.9)mL and(3.2±0.4)mSv],the differences were statistically significant(both P<0.05),and the contrast agent dose and ED in group A were decreased by approximately 34.6%and 65.6%,respectively,compared to those in group B.Conclusions:In CABG patients with heart rate≤65 beats/min and regular rhythm,the use of 70 kV combined with a high-pitch scanning mode can significantly reduce radiation dose and contrast agent dose without compromising image quality.