CT冠脉成像中胸廓径线与图像质量的相关性研究

目的 探讨双源CT冠脉成像中胸廓前后径及左右径与图像质量的相关性,以获得最优化降低辐射剂量的可能性。 方法 收集我院双源CT冠脉成像检查的患者118例,分为A25 kg/m2 ≤体质量指数(BMI)值<30]、B(BMI值<25 kg/m2)两组。A组患者58例,平均年龄59.9岁;B组患者60例,平均年龄60.1岁。扫描参数:准直64×0.6 mm,重建层厚0.75 mm,重建间隔0.7 mm,FOV 150~180 mm,根据心率自动调整螺距。A组:管电压100 kV,管电流330 mAs;B组:管电压100 kV,管电流220 mAs。采集图像后,测量胸廓前后径(AP)、左右径(RL),及所在层面(共5个层面)冠脉、背脊肌的CT值和噪声(SD),并计算冠脉相对于背脊肌的对比噪声比(CNRa)、信噪比(SNRa)。应用统计学软件进行CNRa、SNRa与胸廓AP、RL、BMI的相关性检验。 结果 A、B两组RL的5个层面与CNRa具有相关性(P<0.05),A、B两组中除A组第iii、iv层外,均与CNRa具有相关性(P<0.05),除A组第ii、iv层、B组第v层外,BMI均与CNRa具有相关性(P<0.05)。A组CNRa与RL的相关系数除第ii层面外,都大于其与AP的相关系数,B组CNRa、SNRa与RL的相关系数均大于其与AP的相关系数。A组除第iii层面外,CNRa、SNRa与AP的相关系数大于其与BMI的相关系数;B组除第ii层面外,CNRa与AP的相关系数大于其与BMI的相关系数。 结论 在双源CT冠脉成像检查中,图像质量与胸廓径线(左右径、前后径)的相关性大于与BMI的相关性。采用胸廓径线作为降低射线剂量的参考标准更具有临床实用意义。

Image Quality Adapted Thoracic Diameters in CT Coronary Artery Imaging

Objective To evaluate the correlation between image quality and thoracic diameters, anteroposterior diameter (AP) and right-left diameter(RL) for the optimization of reducing radiation dose in coronary artery imaging with Dual-source CT. Methods 118 patients underwent CT coronary artery imaging(CTCA)were divided into two groups (A and B) according to body mass index (BMI). There were 58 patients in group A with BMI values ≥ 25 kg/m2 and <30 kg/m2; and 60 patients in group B with BMI values <25 kg/m2. Scan parameters:collimation 64×0.6 mm, reconstruction slice thickness 0.75 mm, reconstructin interval 0.7 mm, FOV 150-180 mm, the pitch adjusted according to heart rate automatically. CT imagings were obtained with tube voltage 100 kV, tube current 330 mAs (group A) and 100 kV, tube current 220 mAs (group B). The contrast-noise ratio (CNR), signal to noise ratio (SNR),as well as blind correlation test score values were calculated to establish the relationship among BMI, AP, RL and CNR, SNR; Results RL of five levels in groups of A, B were correlated to CNRa (P<0.05). In group A and B (except iii, iv level of Group A), AP were associated with CNRa (P<0.05). In addition to ii, iv level of group A, v level of group B, BMI were associated with CNRa (P<0.05). The correlation coefficient of CNRa and RL of group A except ii level was greater than that of CNRa and AP. The correlation coefficient of CNRa, SNRa and RL of group B was greater than that of CNRa, SNRa and AP. Except iii level, the correlation coefficient of CNRa, SNRa and AP of group A was greater than that of CNRa, SNRa and BMI. Except ii level, the correlation coefficient of CNRa and AP of group B was greater than that of CNRa and Conclusion Thoracic diameter of RL can be used as a guider to select the appropriate scan protocol in the coronary imaging acqusition with dual-source CT.