双源CT冠状动脉血管成像中降低团注追踪触发监测频率的可行性研究

Feasibility of reducing bolus-tracking monitor frequency in coronary CT angiology with dual-source CT

目的探讨双源CT冠状动脉CTA中降低团注追踪触发监测频率的可行性。方法前瞻性收集120例lf伍床疑似冠心病的患者，按放射科检查登记顺序，以A、B、C组循环的方式分组，每组40例。采用团注追踪程序自动触发技术，A、B、c组均在注射对比剂后10S开始监测，监测频率分别为1．14、1．47、2．00s，触发阈值均为100HU，进行冠状动脉CTA检查。评价图像质量，客观评价指标包括主动脉根部（AO）的信噪比（SNR）和对比噪声比（CNR），以及左主干（LM）、右冠状动脉近段（RCA）的CNR，并对血管节段进行主观评分。记录3组患者监测时ROI达到阈值时的监测次数、达到阈值时的CT值和有效辐射剂量（ED）。采用单因素方差分析比较3组间客观评价指标、监测指标和辐射剂量的差异，采用X2检验评价3组间主观评分的差异。结果3组间AO、RCA和LM的SNR和CNR的差异均无统计学意义（P均〉0．05）。A、B、C组的图像质量评分分别为（1．879±0．042）、（1．876±0．042）、（1．881±0．042）分，差异无统计学意义（X2=0．003，P〉0．05）。A、B、C组达到阈值时的监测次数分别为（4．78±2．37）、（3．76±1．39）、（2．77±0．99）次，ED分别为（0．058±0．031）、（0．031±0．011）、（0．021±0．007）mSv，差异均有统计学意义（F值分别为9．009、31．998，P均〈0．01）；达到阈值时的CT值分别为（133±24）、（142±39）、（137±26）HU，差异无统计学意义（F=0．575，P=0．565）。结论在进行双源CT冠状动脉CTA检查时，降低团注追踪触发监测频率可行。采用2S监测频率的触发扫描技术，在获得满意图像质量的同时，可以显著降低辐射剂量。

Objective To investigate the feasibility of reducing bolus-tracking monitor frequency in coronary CT angiography （CTA）. Methods This prospective study including 120 patients with suspected coronary artery disease （CAD）. According to the examination registration order, the patients were divided into groups A, B and C （n=40 for each group）. All patients underwent coronary CTA with bolus-tracking technology, and were monitored at 10 s after the injection of contrast. The monitoring frequency of bolus- tracking for Group A was every 1.14 s, that for Group B was every 1.47 s, and for Group C was every 2.00 s, while the trigger threshold was set as 100 HU. To evaluate the image quality, the objective evaluation included signal noise ratio （SNR） and contrast noise ratio （CNR） of aorta （AO）, CNR of left main coronary artery （LM） and right coronary artery （RCA）, and the subjective score was recorded for each coronary artery segment. The monitoring times when CT density of the region of interest （ROI） reached the threshold, the CT value and the effective dose （ED） in the 3 groups were recorded. Objective image quality, monitoring parameters and radiation dose were compared using analysis of variance method, subjective image quality was compared with X2 tests. Results There was no significant difference in AO （SNR and CNR）, LM （CNR） and RCA （CNR） among the 3 groups, respectively （P〉0.05）. Subjective image quality scores of groups A, B, C were （1.879±0.042）, 0.876±0.042）, （1.881±0.042）, with no significant difference （X2=0.003,P〉0.05）. The monitoring times of to reach the threshold in groups A, B, C were （4.78±2.37）, （3.76±1.39）, （2.77＋0.99）, and ED were （0.058±0.031）,（0.031±0.011）, （0.021±0.007） roSy, with the significant difference （F=9.009, 31.998, respectively, P〈0.01）. Peak CT values during monitoring among three groups were （133±24）, （142±39）, （137±26） HU, respectively, with no significant difference （F=0.575,P=0.565）. Conclusions It is feasible to reduce monitoring times when performing coronary CTA in dualsource CT scanner. The bolustracking monitor frequency in every 2 seconds can not only obtain satisfactory image quality, but also significantly reduce radiation dose.