CAJ | 학술논문

目的：评价256层CT前瞻性心电门控冠状动脉成像的图像质量与辐射剂量，并与回顾性心电门控对照分析。方法共200例患者纳入研究。100例行前瞻性心电门控的患者分为2组：(1)心率≤70次/min( bpm )50例，数据采集时间窗设在心动周期的75％期相（A组）；(2)心率＞70 bpm 50例，数据采集时间窗设在心动周期的45％期相，包含5％宽容度（B组）。另外100例行回顾性心电门控的患者亦分为2组：(3)心率≤70 bpm 50例，最大管电流输出设在75％期相（C组）；(4)心率＞ 70 bpm 50例，最大管电流输出设在45％与75％期相（D组）。所有患者由数字表法随机分组。采用4分法半定量分析冠状动脉节段及整体评分。采用Mann-Whitney U检验比较组间图像质量，采用t检验比较组间的辐射剂量；并对100例前瞻性心电门控检查者冠状动脉图像质量与平均心率进行ROC分析及相关分析。结果在共2338个冠状动脉节段中，图像质量优秀或良好（评分1或2分）者A组中达到96.5％( 585/606)，B组为77.7％(445/573)，C组为96.1％( 548/570)，D组为85.7％ (505/589)，冠状动脉节段图像质量A组与C组比较差异无统计学意义（Z＝ -1.351,P＞0.05）；B组和D组差异有统计学意义（Z＝-2.236,P＜0.05）。前瞻性心电门控检查ROC分析及相关分析显示，平均心率与冠状动脉图像质量密切相关(r＝0.577，P＜0.01)，平均心率78 bpm可做为满足诊断图像的最高临界点心率（ROC曲线下面积为0.827，P＜0.05）。A组[(2.6±0.5)mSv]相对C组[(10.6 ±2.3) mSy]平均辐射剂量减少75％,B组[(4.0 ±0.7) mSy]相对D组[ (13.0±1.4) mSy]平均辐射剂量减少69％。结论 256层CT低剂量前瞻性心电门控成像可获得与回顾性心电门控相似的满足诊断需要的图像质量，并可应用于高心率检查者。
목적：평개256층CT전첨성심전문공관상동맥성상적도상질량여복사제량，병여회고성심전문공대조분석。방법 공200례환자납입연구。100례행전첨성심전문공적환자분위2조：(1)심솔≤70차/min( bpm )50례，수거채집시간창설재심동주기적75％기상（A조）；(2)심솔＞70 bpm 50례，수거채집시간창설재심동주기적45％기상，포함5％관용도（B조）。령외100례행회고성심전문공적환자역분위2조：(3)심솔≤70 bpm 50례，최대관전류수출설재75％기상（C조）；(4)심솔＞ 70 bpm 50례，최대관전류수출설재45％여75％기상（D조）。소유환자유수자표법수궤분조。채용4분법반정량분석관상동맥절단급정체평분。채용Mann-Whitney U검험비교조간도상질량，채용t검험비교조간적복사제량；병대100례전첨성심전문공검사자관상동맥도상질량여평균심솔진행ROC분석급상관분석。결과 재공2338개관상동맥절단중，도상질량우수혹량호（평분1혹2분）자A조중체도96.5％( 585/606)，B조위77.7％(445/573)，C조위96.1％( 548/570)，D조위85.7％ (505/589)，관상동맥절단도상질량A조여C조비교차이무통계학의의（Z＝ -1.351,P＞0.05）；B조화D조차이유통계학의의（Z＝-2.236,P＜0.05）。전첨성심전문공검사ROC분석급상관분석현시，평균심솔여관상동맥도상질량밀절상관(r＝0.577，P＜0.01)，평균심솔78 bpm가주위만족진단도상적최고림계점심솔（ROC곡선하면적위0.827，P＜0.05）。A조[(2.6±0.5)mSv]상대C조[(10.6 ±2.3) mSy]평균복사제량감소75％,B조[(4.0 ±0.7) mSy]상대D조[ (13.0±1.4) mSy]평균복사제량감소69％。결론 256층CT저제량전첨성심전문공성상가획득여회고성심전문공상사적만족진단수요적도상질량，병가응용우고심솔검사자。
Objective To compare the image quality and patient radiation dose of coronary computed tomography angiography (CCTA) received by prospectively-gated step-and-shoot (SAS) technique with those obtained by retrospectively-gated spiral (RGS) technique on a 256-slice CT scanner. Methods A total of 200 patients were enrolled in this study. One hundred patients underwent CCTA with SAS mode were subdivided into two groups: ( 1 ) 50 patients with an average heart rate (HR) ≤70 bpm were scanned with a data acquisition time window centered at the 75％ of the R-R cycle ( group A) and (2) 50 patients with HR ＞ 70 bpm were scanned with the data acquisition time window centered at the 45％ of the R-R cycle, including a phase tolerance of ±％ (group B). Other 100 patients underwent CCTA with RGS mode and ECG-based tube current modulation were also subdivided into two groups: (3) 50 patients with HR ≤70 bpm were scanned with cardiac dose right set to phase of 75％ (group C) and (4) 50 patients with HR ＞ 70 bpm were scanned with cardiac ose Rdight set to phases of 45％ and 75％ (group D). All patients were grouped in randomized order. The image quality of CCTA were evaluated using a rank scale from 1 to 4 ( 1 : excellent ; 4 : non-assessable ) . Radiation dose of the four groups received was also estimated. The image quality between groups was compared by Mann-Whitney U test. The radiation dose between groups was compared by t test. For the 100 patients received by prospective ECG-gated CCTA, the receiver operating characteristic curve (ROC) was used to analyze the CCTA image quality and average heart rate to determine the uppercutoff of HR for obtaining diagnostic coronary images with SAS mode. A spearman correlation analysis was also performed to analyze the correlation of HR and image quality in patients underwent CCTA with SAS mode. Results Of 2338 coronary artery segments, excellent or good image quality( score of 1 or 2) was achieved in 96. 5％ (585 of 606) in group A, 77.7％ (445 of 573 ) in B,96. 1％ (548 of 570) in C, and 85. 7％ (505/589) in D, with no significant difference for A vs C(Z ＝- 1. 351 ,P ＞0. 05) and with significant differenceS for B vs D (Z＝ -2. 236,P ＜0. 05). Linear correlation analysis indicated a significant degradation of image quality with the increase of heart rate using SAS mode (Spearman correlation, r ＝ 0. 577, P ＜0. 01 ). ROC analysis established an upper HR threshold of 78 bpm for obtaining diagnostic image quality using SAS mode( AUC ＝ 0. 827, P ＜ 0. 05 ). The average radiation dose in group A [ ( 2. 6 ± 0. 5 ) mSv]reduced 75 ％ comparing with that in group C [ ( 10. 6 ± 2. 3 ) mSy], and the average radiation dose in group B [ ( 4.0 ± 0. 7 ) mSy]reduced 69％ comparing with that in group D [ ( 13.0 ± 1. 4) mSv]. Conclusion Using SAS mode to perform low-dose CCTA with 256-slice helical CT could keep the image quality and reduce radiation dose significantly. Our preliminary experience suggests a good promise of this technique which could be applied to a wider group of patients such as with higher heart rates.