心率波动患者多排螺旋CT冠状动脉成像时相重建方法的比较

目的：探讨绝对延迟收缩末期重建、相对延迟收缩末期重建及舒张中末期重建3种重建时相与心率波动患者多排螺旋CT（MSCT）冠状动脉成像阶梯状伪影的关系。材料和方法：选择行64层螺旋CT冠状动脉成像检查中出现心率波动患者20例，平均心率（65.1±5.0）bpm（55～75bpm），扫描过程中心率波动范围≥5bpm。采用64层MSCT（Siemens Somatom Sensation 64 Cardiac）进行扫描。使用相对延迟方式选出最佳收缩末期及舒张中末期时相。使用绝对延迟方式选出最佳收缩末期时相。由2名本专业有3年以上工作经验的放射科医师双盲情况下对图像的阶梯伪影评价打分。阅片结果采用SPSS 11.5软件包进行观察者间Kappa检验，如具有较好一致性则进一步进行评价结果的组间χ2检验。结果：对于评价结果两个阅片者间具有很好的一致性，Kappa值为0.991（P=0.000）。3种重建时相阶梯状伪影评价差异有统计学意义（P<0.05），相对延迟及绝对延迟收缩末期重建优于舒张中末期重建。相对延迟收缩末期重建与绝对延迟收缩末期重建之间差异无统计学意义，但是绝对延迟收缩末期重建优质图像比例高于相对延迟收缩末期重建。结论：使用绝对延迟收缩末期重建能有效减小MSCT冠状动脉成像中因心率波动引起的阶梯状伪影从而提高图像质量。

Multi-detector spiral CT coronary angiography in arrhythmia: selection of reconstruction phase

Objective：To assess the effect of different reconstruction phase selection strategies on the image quality of MSCT coronary angiography in patients with irregular heart beats during examination.Materials and Methods：Twenty patients who experienced heart rate shift of more than 5 beats per minute（bpm） during CT coronary angiography were included in the study mean heart rate（65.1±5.0）bpm.CT coronary angiography examinations were performed with a 64-slice scanner.Image reconstruction based on relative timing was performed with multi-phasic reconstruction.Then the best phases at endsystolic and mid-diastolic stages were selected.Reconstruction based on absolute timing was performed with the reconstruction of the same slice.Then the best image at end-systolic stage was selected.Evaluation of stair-step artifacts were performed with a 4-point ranking scale.The results were analyzed with SPSS 11.5 for Kappa test and inter-group Chi-square test.Results：Two radiologists were in accordance with the rating of the stair-step artifacts（Kappa=0.991）.The absolute delay end-systolic reconstruction and the relative delay end-systolic reconstruction provided superior image quality compared with relative delay mid-diastolic reconstruction（P0.05）.Absolute delay had relatively higher percentage of excellent images than relative delay in end-systolic stage.Conclusion：In patients with irregular heart beats,better image quality and less stair-step artifacts can be obtained with end-systolic reconstruction,especially with absolute delay.