Patient-tailored versus fixed post-trigger delay for optimized scan timing: a comparison of image quality and diagnostic confidence in run-off CT angiography.

OBJECTIVES

This study aimed to validate bolus tracking using a patient-tailored post-trigger delay (PTD) in run-off computed tomography angiography (CTA) and to compare the resulting image quality and diagnostic confidence with those obtained using a fixed PTD.

MATERIALS AND METHODS

Participants were prospectively assigned to either fixed (10 s) or patient-tailored cohorts. We measured attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) for each vascular segment. Two radiologists evaluated qualitative image quality and diagnostic confidence. Differences in quantitative variables between cohorts were assessed using Student's t-test or Mann-Whitney U test, while categorical variables were assessed using chi-square test. Generalized least squares linear regression was used to evaluate the effects of different cohorts, anatomical locations, and their interactions on attenuation.

RESULTS

The patient-tailored cohort showed significantly higher attenuation from the popliteal artery to the foot artery (all p < 0.001), with a patient-tailored PTD ranging from 8.10 to 14.90 s. Generalized least squares linear regression revealed more uniform attenuation in patient-tailored cohort and decreasing attenuation in fixed cohort (decrease of 89.06 HU in foot artery, p < 0.001). There was no significant difference in image noise between cohorts (p = 0.060), while SNR and CNR were higher in the patient-tailored cohort at most measurement locations (all p < 0.05). Both radiologists rated the patient-tailored cohort as having better qualitative image quality and more segment with unrestricted diagnostic confidence.

CONCLUSIONS

Bolus tracking with patient-tailored PTD provides reliable scan timing, resulting in optimized vessel opacification, improved image quality, and enhanced diagnostic confidence in run-off CTA.

KEY POINTS

Question Is this novel bolus tracking algorithm for run-off CT angiography feasible for improving image quality by automatically predicting patient-tailored post-trigger delay (PTD) through real-time monitoring. Findings Patient-tailored PTD improved image quality and distal artery opacification through reliable scan timing, thereby enhancing diagnostic confidence. Clinical relevance Patient-tailored PTD improved image quality, not only demonstrating the potential for reducing contrast media volume but also eliminating the need for compensatory scans from the feet to the knee, thus minimizing additional radiation exposure.