单扇区重建算法改善非预期自由呼吸640层CT冠状动脉成像图像质量的可行性研究

Half-cycle reconstruction improve image quality in high heart rate patients with unanticipated free-breathing 320-row coronary CT angiography

目的探讨单扇区重建算法改善高心率患者非预期自由呼吸640层CT冠状动脉成像图像质量的可行性。方法2011年3月1日-8月31日期间，行640层CT冠状动脉成像时发生非预期自由呼吸的31例心率大于65次／min的患者被纳入本研究。31例患者的CT原始数据均采用单扇区重建算法、多扇区重建算法进行CT容积数据重建。由两名心血管放射医师以优（1分）、良（2分）、差（3分）3个等级独立评价每个病例的15个冠状动脉节段和左、右肺血管的图像质量。比较两种重建算法的信噪比、对比噪声比。结果采用单扇区重建算法，图像质量可诊断（优＋良）的冠脉节段占97．9％，相比较于多扇区重建算法69．5％的可诊断率，两组有明显的统计学差异（P〈0．001）。两组间肺血管的图像质量也有明显的统计学差异（P〈0．001）。单扇区重建组的信噪比显著低于多扇区重建组（14．0±3．4比17．6±4．2，P〈0．001）。两种重建方法的对比噪声比在左冠状动脉主干、右冠状动脉初段、中段和末段均无统计学差异（P〉0．05）。结论单扇区重建技术可以改善非预期自由呼吸病例的640层CT冠状动脉成像的图像质量。

Objective To assess the image quality of half-cycle reconstruction of free-breathing 320-detector row coronary CT angiography （CTA） in patients with heart rates above 65 beats per minute. Methods From March 1 to August 31, 2011, 31 patients with unanticipated free-breathing during coronary CTA were included in the study. CTA was performed using the standard breath-holding method. All images were reconstructed using half-cycle reconstruction （HCR） and multi-cycle reconstruction （MCR） methods. The image quality for 15 segments of all coronary arteries was scored as 1 （excellent）, 2 （good）, and 3 （poor）. The signal- to-noise ratio （SNR） and contrast-to-noise ratio （CNR） were compared. Results With HCR, 97.4% of the coronary artery segments were evaluable with image quality scores of 1 and 2 compared to 65.6% with MCR group （P 〈 0.001）. The image quality score of lung vessels was also significantly higher with HCR than that with MCR （P 〈 0.001）. The SNR was significantly （P 〈 0.001） lower with HCR （14.0 ＋ 3.4） than that with MCR （17.6 ＋ 4.2）. The CNRs were not significantly different in the left main coronary artery （P = 0.052）, proximal right coronary artery （ P = 0.058）, middle right coronary artery （P = 0.081） and distal right coronary artery （ P = 0.112） between the two reconstructive methods. Conclusions Half-cycle reconstruction can improve image quality of unanticipated free-breathing on 320-detector row coronary CTA in patients with heart rates above 65 beats per minute.