Fixed Versus Tailored Scan Delay for Pancreatic Phase Acquisition: Comparison of Scan Timing Adequacy.

Abstract

Purpose: To compare the scan timing adequacy for the pancreatic phase between fixed and tailored scan delay in the pancreatic protocol CT with a bolus-tracking technique.

Materials and methods: This retrospective study included patients who underwent pancreatic protocol CT using a fixed scan delay of 20 s from January 2020 to November 2022 (conventional group) and those using a tailored scan delay from January 2023 to July 2024 (tailored group). Tailored scan delay was identified to be the same as the time from contrast injection to reaching to trigger threshold of 100 HU (TimeTRIG). The scan delay ratio (SDR) was calculated by dividing the scan delay by TimeTRIG. Two radiologists assessed the scan timing adequacy for the pancreatic phase and classified it into 3 categories: early, appropriate, and late. The SDR and scan timing adequacy were compared between the conventional and tailored groups.

Results: This study involved 128 patients (75 men; median age, 71 y), including 63 and 65 in the conventional and tailored groups, respectively. The median SDR was significantly different between the two groups (1.2 and 1.0 in the conventional and tailored groups; P<0.001). The proportion of appropriate scan timing for the pancreatic phase was higher in the tailored group (55/65; 84%) than in the conventional group (47/63; 75%); however, no statistical significance was observed (P = 0.36).

Conclusions: The tailored scan delay tended to provide a higher rate of appropriate scan timing for the pancreatic phase compared with the conventional protocol using a fixed scan delay of 20 s.