Feasibility Of Reduced Radiation Dose And Iodine Load In Lower Extremity Computed Tomography Angiography

Objective: To evaluate the feasibility of reduced radiation dose and low-concentration contrast medium in lower extremity computed tomography angiography (CTA) compared with conventional automatic exposure control CTA.Methods: A total of 64 subjects underwent dual-source CTA operating in dual-source, high-pitch mode, using both high-concentration contrast medium (group A, n = 31; iomeprol 400 mg l/mL) and low-concentration contrast medium (group B, n = 33; iodixanol 270 mg l/mL). Group A was scanned using a reference tube voltage of 120 kVp and reference 100 mAs under automatic exposure control with iterative reconstruction. Group B was scanned using low tube voltage (80 kVp or 100 kVp if body mass index >= 25 kg/m(2)) and fixed 120 mAs, along with iterative reconstruction. Images of the two groups were compared regarding attenuation, image noise, signal-to-noise ratio, contrast-to-noise ratio, iodine load, radiation dose, and visual quality assessment (general, enhancement, sharpness, and noise) in various locations of CTA.Results: The averages of mean attenuation (765.29 +/- 146.3 vs. 581.11 +/- 163.99 HU), signal-to-noise ratio (42.93 +/- 10.85 vs. 30.97 +/- 9.54), and contrast-to-noise ratio (39.89 +/- 10.53 vs. 27.82 +/- 9.12) were significantly higher in group A than in group B (all p < 0.05). Visual quality comparisons in each location were not significantly different.Conclusion: In lower extremity CTA, reduced radiation dose and iodine load in CTA scans with low-concentration contrast medium and low tube voltage may not yet be a feasible replacement for conventional automatic exposure control CTA.