Fixed Versus Patient-Specific Trigger Delay in High-Pitch Computed Tomography Angiography of the Aorta Prior to Transcatheter Aortic Valve Implantation: Assessment of Image Quality and Homogeneity of Vessel Enhancement.

Objective: The aim of the study is to compare the image quality and homogeneity of vessel enhancement in high-pitch CT-angiography of the aorta (CTA) prior to transcatheter aortic valve implantation between bolus tracking with a fixed trigger delay and bolus tracking with a patient-specific trigger delay.

Materials and methods: In this retrospective study, consecutive patients who received a CTA of the aorta prior to transcatheter aortic valve implantation between January 2023 and June 2024 were included. Patients were imaged using either bolus tracking and a fixed trigger delay (Group A; 15 seconds) or bolus tracking and a patient-specific trigger delay (Group B; FAST Bolus; Siemens Healthineers AG). The same contrast injection and scan protocol were used in both groups. Vessel enhancement was measured at multiple craniocaudal locations. Subjective image quality was assessed by 2 readers using 5-point Likert scales. Likert scores were analyzed using Wilcoxon rank-sum tests. Enhancement was assessed with a mixed-effects model.

Results: Sixty-five patients (28 females) were assessed in each group. Patient demographics (both 74 ± 12 years; P = 0.58, body mass index: 26.0 vs 26.2 kg/m2; P = 0.79) and radiation dose (CTDIvol: 3.4 vs 3.5 mGy; P = 0.55) did not differ significantly between the two groups. Mean CT attenuation was 489 HU versus 469 HU in the ascending aorta and 428 HU versus 464 HU in the common femoral artery for fixed and patient-specific delays, respectively. Enhancement in the femoral arteries was significantly lower in the fixed delay group (P < 0.05), while there was no significant difference at other vessel locations. Diagnostic image quality and enhancement at the femoral artery were rated significantly better for the patient-specific trigger delay by one reader (both P < 0.05).

Conclusions: Bolus tracking with a patient-specific trigger delay improved the craniocaudal homogeneity of vessel enhancement and subjective image quality at the distal access site as compared to bolus tracking with a fixed trigger delay in high-pitch CTA prior to TAVI.