Optimized contrast enhancement and homogeneity in aortic CT angiography: bolus tracking with personalized post-trigger delay

Background: The bolus tracking technique has been used for decades, yet still faces the challenging task of determining the optimal scanning time for individuals. Our study aimed to assess the feasibility of a novel bolus tracking method with a personalized post-trigger delay (PTD) to optimize scanning time and achieve optimized enhancement and contrast homogeneity in aortic computed tomography angiography (CTA).

Methods: Participants undergoing aortic CTA with bolus tracking were prospectively assigned to two different groups: Group A with a fixed 6-second PTD and Group B with a personalized PTD. A reader assessed objective image quality and evaluated enhancement level and contrast homogeneity; two readers rated subjective image quality. Student's t-test or Mann-Whitney U test was used to determine quantitative data, whereas the Chi-square test compared categorical variables between the two groups.

Results: Group A comprised 70 participants [13 female; mean ± standard deviation (SD) age 58±11 years], whereas Group B included 70 participants (18 female, mean ± SD age 59±12 years) with the personalized PTD ranging from 7.8 to 14.1 seconds (mean ± SD, 11.2±1.5 seconds). Group B demonstrated improved mean attenuation and contrast-to-noise ratio (CNR) of aortoiliac artery [417.55±71.55 vs. 345.71±60.41 Hounsfield units (HU), 16 vs. 13, both P<0.001, respectively]. Enhancement level (78.6% vs. 37.1%, P<0.001), contrast homogeneity (94.3% vs. 64.3%, P<0.001), and subjective ratings (scores greater than or equal to 4, 91.4% vs. 68.6%, P<0.001) were superior in Group B compared to Group A. Enhancement level of abdominal aortic branches in aortic dissection or aortic aneurysm patients was optimized in Group B (74.5% vs. 23.3%, P<0.001).

Conclusions: Bolus tracking with a personalized PTD can improve enhancement level and contrast homogeneity in aortic CTA due to reliable scan timing.