Feasibility of Low Tube Voltage CTA in Abdominal Aorta and Lower Extremity Artery

Purpose: To compare the radiation dose and image quality of abdominal aorta and lower extremity artery CTA by using 80 kV and 120 kV tube voltage on a 128-slice CT and to evaluate the feasibility of low tube voltage technique. Methods: Forty-eight patients who underwent abdominal aorta and lower extremity artery CTA were randomly assigned to two different protocols in this trial: group A(n=24) was examined with 120-kV protocol and group B(n=24) was examined with 80-kV protocol. Objective indices such as vascular attenuation, image noise(N) and contrast-to-noise ratio(CNR) were analyzed. Subjective image quality was assessed by two observers in consensus using a four-point scale. Dose length product(DLP) was recorded. Image quality and radiation dose were compared with t test between the two groups. Results: Vessel attenuation was significantly higher in group B than that in group A(P0.05). Noise was significantly higher in group B than that in group A(57.95±19.23HU vs. 22.78±6.15HU, P0.05),however, there was no significant difference of CNR between them(15.69±5.39 vs.14.85±5.61, P﹥0.05). Subjective image quality was rated similar in both groups(P0.05). The effective dose of group B was significantly lower than that of group A(DLP:274.96±20.72 mGy·cm vs. 1025.50±64.15 mGy·cm, P0.05). Conclusion: Eighty kV tube voltage is feasible for abdominal aorta and lower extremity artery CTA, the radiation dose can be significantly reduced and the image quality can meet the diagnostic request.