Abstract：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 end-systolic 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(P<0.05). 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.
2010, Vol. 21 
