Lower limbs low voltage (80 kV) CTA: lower radiation dose delivered and less contrast medium with preservation of image quality

Purpose: To compare the intravascular enhancement in low dose (80 kV) CT- angiography of lower limbs performed with a reduced dose of high concentration contrast medium (CM) (75 ml of iopromide 370) in comparison with standard protocol at 100kV performed injecting a full dose of CM (100 ml). Methods and Materials: 120 patients (84 males; mean age 71.4 years) were randomly directed in two different protocols of CT-angiography of lower limbs, performed with standard tube parameters (100kV) and administration of 100 ml of CM at 4 ml/s or with low voltage protocol (80 kV) with injection of 75 ml of CM at 3 ml/s. In each patient density values of 4 region of interest (ROI) at the level of the abdominal aorta, popliteal artery, of a vessel of the leg ad in a psoas muscle were measured. Risk factors, serum creatinine, the signal to noise ratio and x-ray dose (DLP) were also registered. Results: The density values of aorta were significantly higher in 80 kV protocol in comparison with the standard protocol (P=0.001); no statistically significant differences were noted in the vascular enhancement of popliteal or leg artery. There was no statistically significant difference (P = 0.152) in image quality measured with SNR. The DLP in the 80 kV protocol was significantly lower than the standard approach (P < 0.05). Conclusion: 80 kV CT angiography of lower limbs allows to significantly reducing the amount of administered contrast medium preserving the image quality and lowering the radiation dose of about 30%.