冠脉CTA自由呼吸扫描与屏息扫描的辐射剂量对比研究

Comparative Study on the Radiation Dose of Coronary CT Angiography with Free-Breathing and Breath-Holding

目的探讨自由呼吸与屏息两种不同方式下行冠状动脉CT血管造影(Coronary CT Angiography,CCTA)扫描对辐射剂量的影响。方法采用最新的高时间分辨率宽体探测器CT,对102位行CCTA扫描的患者分别在自由呼吸和屏息时进行自动门控心率测试,比较同一名患者自由呼吸和屏息下的心率、扫描期相及相对应的预估辐射剂量长度乘积(Dose LengthProduct,DLP)。结果高心率患者(HR>75bpm,n=16)屏息后少数患者(n=4)辐射剂量上升(屏息后与自由呼吸下DLP之比为156.26%±1.97%),其余患者的扫描期相无变化。中等心率患者(HR为65~75 bpm,n=35)中,超过半数(n=19)屏息状态下扫描期相缩短,辐射剂量降低(期相由40%~80%降低为75%或者70%~80%时,DLP分别为自由呼吸下的42.48%±2.46%和54.35%±1.66%),其余患者期相无变化。中低心率患者(HR为60~65 bpm,n=35)中,多数(n=19,54.3%)在屏息状态下辐射剂量降低(74.02%±6.82%),但有个别中低心率的患者(n=4,11.4%)辐射剂量有大幅度的上升(177.31%±16.06%)。低心率(<60 bpm)的患者扫描期相和剂量无变化。结论应当根据患者实际情况选择自由呼吸或屏息的冠脉CTA可以优化扫描期相,降低辐射剂量。

Objective To compare the radiation dose of coronary CT angiography （CCTA） with free-breathing and breath-holding. Methods A total of 102 patients underwent coronary CTA. Heart rate （HR） test was performed under free-breathing and breath-holding. Radiation dose was estimated and compared. The scan was performed either during breath-holding or free-breathing with the lower estimate radiation dose length product （DLP）. Results For the patients with high HR （〉75 bpm, n=16）, 4 patients （25%） had their DLP increased to 156.26±1.97% after breath holding. For the patients with intermediate HR （65-75 bpm, n=35）, more than half （n=19） received reductions on explosure interval and radiation dose （DLP reduced to 42.48%±2.46% and 54.35%±1.66% of that with free-breathing）. For the moderate-HR patients, more than half （n=19, 54.3%） had their DLP reduced to 74.02%±6.82% while a minority （n=4, 11.4%） had their DLP greatly increased to 177.31%±16.06%. The low-HR patiends neither had their explosure phase nor DLP changed after breath-holding. Conclusion Breath-holding or free-breathing CCTA should be preformed selectively to optimize the scan phase and reduce the radiation dose.