To evaluate the use of 80 kVp and iterative model reconstruction (IMR) in lower extremity computed tomography angiography (CTA).

Sixty patients were randomly assigned to Group A or Group B (both n=30) to further undergo CTA. Group A received Protocol 1 (P1) with 120 kVp, 180mAs, and 100mL of contrast agent with filtered back-projection (FBP). Group B received Protocol 2 (P2) and Protocol 3 (P3) with 80 kVp, 140mAs and 75mL of contrast agent with hybrid iterative reconstruction (P2) and IMR (P3). Mean intravascular attenuation (MIA), image noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were compared. Radiologists assessed image quality on a 5-point scale, and radiation was compared between both groups.

Group A had 9 men and 21 women (mean age, 68.2±9.3 years [range: 53–85 years]), and Group B had 20 men and 10 women (mean age, 64.8±10.4 years [range: 37–81 years]). The MIA of P2 and P3 were significantly larger than that of P1 (P<0.01). The CNR and SNR of P3 were significantly higher than those of P1 and P2 (P<0.01). The interobserver agreement had Kappa values of 0.78, 0.77, and 0.81 for P1, P2, P3, respectively. The mean CT volume dose index and dose-length product of Group B were lower than those of Group A (P<0.01).

Lower extremity CTA using 80 kVp and IMR is useful for lower radiation and contrast agent dose while preserving image quality. IMR can also provide better image quality for small-caliber vessels below the knee than HIR.