RESUMO
OBJECTIVES: Our aim was to assess image quality and radiation dose of low-voltage high-pitch computed tomography angiography of the infrarenal aorta and lower extremities and evaluate the efficacy of test injection technique using a monitoring scan at knee level. METHODS: A total of 60 patients with suspected peripheral arterial disease were divided into 2 groups: group 1 (30 patients, 80 kVp, high pitch [3.2], and hybrid iterative reconstruction [sinogram-affirmed iterative reconstruction]) and group 2 (30 patients, 120 kVp, low pitch [1.0], and filtered back projection reconstruction). The test injection technique at knee level was used to determine the scan delay time in group 1. The image quality and radiation exposure were compared. RESULTS: There were significant differences between the 2 groups in mean (SD) arterial attenuation (80 vs 120 kVp: 507.78 [103.01] vs 317.54 [62.03] Hounsfield units, P < 0.001), mean (SD) signal-to-noise ratio (51.04 [20.29] vs 34.66 [9.94], P < 0.001), and contrast-to-noise ratio (44.83 [17.93] vs 28.26 [9.60], P < 0.001). No difference in subjective image quality was found between the 2 groups (all P > 0.05). The imaging time was significantly shorter in group 1 (2.70 [0.11] vs 14.65 [0.90s], P < 0.001). The mean (SD) effective dose was significantly lower in the 80 kVp group (0.76 [0.06] vs 4.29 [0.63] mSv, P < 0.001). CONCLUSIONS: The 80-kVp high-pitch computed tomography angiography of the lower limbs using sinogram-affirmed iterative reconstruction yields reduction of radiation exposure as well as obtains acceptable image quality if acquisition protocols are used in conjunction with the test injection technique using monitoring scan at knee level to determine the delay time.
