能谱CT对比剂追踪智能触发技术应用于低浓度碘对比剂支气管动脉成像初探

Preliminary applications of spectral CT imaging in angiography of bronchial artery with low concentration of iodine contrast agent

目的探讨能谱CT对比剂追踪智能触发技术在低浓度等渗碘对比剂模式下支气管动脉成像的可行性。方法收集我院胸部增强患者20例,行能谱CT GSI扫描模式下支气管动脉血管成像(CTA)。经留置针注入碘克沙醇(270mgI/ml),剂量1.2ml/kg,流速4.0ml/s,采用对比剂追踪智能法触发扫描。数据均传入工作站,通过GSI viewer软件获得混合能量图像(Quality Check,QC,140kVp)、最佳单能量图像,测定以上两组图像支气管动脉的CNR、SNR,由两位有经验的放射科医师采用盲法对图像进行独立评分。支气管动脉CTA质量的主观评分采用配对t检验,P<0.05具有统计学意义;评分一致性采用kappa检验。结果①本研究患者支气管动脉CTA图像在最佳单能量和混合能量组均显示共55支。最佳单能量组优质支气管动脉共46支(84%),平均主观评分:3.63±0.92;混合能量组优质支气管动脉共28支(51%),平均主观评分:2.57±0.90;两者具有明显统计学差异(t=13.608,P<0.001);两名医师评分结果具有较强一致性(r=0.745,P<0.01)。最佳单能量组图像(CNR:35.1±21.23;SNR:45.10±23.32)CNR、SNR均明显优于140kVp混合能量组(CNR:12.23±9.30;SNR:31.95±17.62)(t=9.865,8.268,P<0.001);②使用低浓度对比剂,患者碘对比剂的碘含量值均低于根据常规对比剂的每公斤体重测量值。结论采用低浓度碘对比剂可以在能谱CT单能量技术优化条件下获得更多优质的支气管动脉图像,提高了支气管动脉的显示率和清晰度。

Objective To investigate the feasibility of spectral CT imaging in angiography of bronchial artery with low concentration of iodine contrast agent .Methods 20 patients in our hospital consecutively underwent enhanced chest CT scan on GSI mode （Discovery CT750 HD ,GE healthcare） .The injection parameters were 1 .2 ml/kg of injection volume , and 4 .0 ml/s of injection speed with iodixanol （270 mgI/ml） .SmartPrep was used to trigger the scan .The source images were conveyed to AW 4 .5 workstation and optimal keV images were obtained by GSI viewer software .We compared 140 kVp QC images （Quality Check） and the optimal keV images after measuring CT value and SD value ,and calculated CNR and SNR of bronchial artery on each patient .5-point scale was used to compare the image quality by 2 experienced radiologists independent and blinded .Results The mean CT value ,mean CNR and mean SNR of the optimal keV images （HU ：269 .22 ± 77 .23 ;CNR：35 .1 ± 21 .23 ;SNR ：45 .10 ± 23 .32） were statistically higher than those in QC images （HU ：160.53 ± 45 .74 ;CNR：12 .23 ± 9 .30;SNR：31 .95 ± 17 .62） （ t =17 .823 ,9 .865 ,8 .268 ,P 〈0 .001） .The subjective score in the optimal keV images （3 .63 ± 0 .92） was higher than that of QC images （2 .57 ± 0 .90） ,（ t =13 .608 ,P 〈0.001） .Totally ;55 bronchial arteries were involved in the study .46 （84% ） of them in optimal keV group met the best quality imaging ,but only 28 （51% ） bronchial artery of QC images met .There was a strong correlation between two physicians （kappa=0.745 ,P 〈0 .01） .Conclusion Low concentration of contrast agent combined with spectral CT imaging gets acceptable image quality in CTA of bronchial artery ,which can reduce contrast agent does in different degrees .