A WEIGHT-BASED contrast protocol for lower-limb CT angiography (CTA) may reduce contrast use and associated costs without compromising diagnostic image quality, according to a prospective study comparing tailored dosing with a conventional fixed-volume approach.
Lower-limb CTA is widely used to assess peripheral arterial disease, a condition in which narrowed or blocked arteries reduce blood flow to the legs. Reliable arterial enhancement is essential for accurate imaging assessment, but standard protocols often use fixed contrast volumes that may expose some patients to more iodine than necessary.
Weight-Based Contrast Protocol Tested in Lower-Limb CTA
The study evaluated whether a weight-based contrast protocol could maintain image quality while lowering contrast exposure. Researchers prospectively enrolled 105 patients who underwent lower-limb CTA using a weight-adjusted contrast regimen of 80-100 ml of contrast medium containing 350 mg I/ml. Outcomes were compared with those of 25 patients who received a standard fixed contrast volume of 120 ml.
Objective image quality measures included arterial attenuation, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Subjective image quality was independently assessed using a five-point Likert scale, and between-group comparisons were analysed using the Mann-Whitney U test.
Lower Contrast Volumes Show Comparable Image Quality
Subjective image quality scores were higher in the fixed-dose group, with statistically significant differences across assessments (all p<0.001). In contrast, most objective image quality measures showed no meaningful difference.
There was no significant difference between groups in arterial attenuation. Although CNR was modestly higher in the standard protocol group (p=0.010), all examinations in both groups remained diagnostically adequate.
Further analysis showed that increasing contrast volume did not significantly influence SNR or CNR. Instead, arterial attenuation and image noise emerged as the primary factors affecting image quality.
Practical Benefits for Routine CTA Imaging
The findings suggest that a weight-based contrast protocol can reduce contrast volume and related costs by 16.7% to 33.3% while preserving diagnostic acceptability. The approach was implemented using standard CT systems, supporting its practicality in routine clinical workflows.
While subjective image quality ratings favoured the fixed-dose strategy, the absence of meaningful differences in key objective measures and the maintenance of diagnostic adequacy indicate that tailored contrast dosing may offer a safe and efficient alternative to fixed-volume protocols in lower-limb CTA.
The authors concluded that weight-based dosing represents a feasible strategy for contrast optimisation, potentially reducing iodine exposure and healthcare costs without sacrificing diagnostic utility.
Reference
Vegas A et al. Weight-based contrast media volume reduction in lower limb computed tomography angiography: a prospective feasibility study. Clin Radiol. 2026;DOI:10.1016/j.crad.2026.107409.
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