Optimized versus conventional trigger threshold for pancreatic phase image acquisition using dual-energy CT at 40-keV: a randomized controlled trial

To evaluate the impact of optimized trigger threshold on 40-keV pancreatic phase images acquired with a dual-energy CT (DECT) protocol.

A cohort of 69 consecutive participants (median age, 72 years) undergoing a pancreatic protocol DECT examination between September to December 2021 were prospectively randomized into two protocols: conventional trigger threshold of 100 HU (Group A, n = 34) and optimized trigger threshold of 30 HU (Group B, n = 35). Pancreatic phase image acquisition was performed with fixed delay of 20 s from the trigger threshold. Two radiologists assessed the 40-keV pancreatic phase images for scan timing adequacy using a binary scale (adequate or inadequate). The proportions of these classifications were compared in the two groups using the Fisher’s test.

The median times to achieve the aortic attenuation of 30 HU and 100 HU were 16.3 s and 22.3 s in Group A, respectively, and was 17.8 s for 30 HU in Group B. The median time difference from 30 HU to 100 HU was 4.5 s in Group A. The scan timing adequacies of pancreatic phase images were classified as adequate (50.0% and 74.3%) or inadequate (50.0% and 25.7%) in Group A and Group B (P = 0.049).

An optimized trigger threshold of 30 HU allows consistent acquisition of adequate pancreatic phase images compared to the conventional trigger threshold of 100 HU for pancreatic protocol DECT at 40-keV which might lead to improved pancreatic lesion conspicuity.