Aortic and Coronary Assessment in Retrospectively Electrocardiogramgated Thoracal-abdominal Dual-source Computed Tomographic Angiography of Aorta

  Objective  To evaluate image quality of aortic and coronary arteries and radiation dose in retrospective electrocardiography (ECG) -gated thoracal-abdominal dual-source computed tomographic angiography (CTA) of aorta.

  Methods  Totally 45 patients who underwent aorta CTA from December 2009 to Novem-ber 2010 were evaluated retrospectively. Among them 23 patients underwent retrospective ECG-gated thoracalabdominal dual-source CTA of aorta, while 22 underwent conventional non-ECG-gated aortic CTA. The attenuation and image noise of 4 parts of aorta (aortic root, aortic arch, abdominal aorta, and aortic bifurcation) were evaluated. Image quality of aortic root and coronary arteries were assessed using a 3-point scale. Attenuation, image noise, image quality, and radiation dose were compared between two groups who underwent different scan protocols.

  Results  Attenuation of 4 different parts of aorta showed no significant difference between two groups (P > 0.05). Image noise was significantly lower in conventional non-ECG-gated group than in retrospective ECG-gated group (P=0.002). The percentage of patients with diagnostic image quality was high in retrospective ECG-gated group:aortic root, 100% (23/23); coronary artery, 83% (19/23), which was significantly higher than in conventional non-ECG-gated group; aortic root, 5% (1/22); coronary artery, 0% (0/22) (P < 0.001). The effective radiation dose was significantly higher in retrospective ECG-gated group than in conventional non-ECG-gated group (P=0.038).

  Conclusions  Retrospective ECG-gated thoracal-abdominal dual source CTA of aorta provides well attenuated whole aorta, well displayed aortic root, and assessable coronary arteries. However, the effective radiation dose used in this mode is higher than that in conventional nonECG-gated aortic CTA.