Replacing true non-contrast imaging with DECT in GI bleeding demonstrates non-inferior diagnostic performance,...

To determine whether a dual-energy CT (DECT) protocol-including arterial and portal-venous phases, virtual non-contrast (VNC) images, and iodine maps-provides non-inferior diagnostic performance to a conventional triphasic CT protocol for gastrointestinal (GI) bleeding.

In this retrospective single-center diagnostic accuracy study, we included all patients who underwent triphasic abdominal CT for GI bleeding between September 2015 and June 2024. For each case, conventional and DECT datasets were generated. Three fellowship-trained abdominal radiologists and two residents independently assessed all cases for active GI bleeding. A consensus review served as the reference standard. Sensitivity and specificity were compared using the Wald method for paired confidence intervals (non-inferiority margin 3%). Diagnostic confidence and reading time were analyzed using the Wilcoxon signed-rank test. Inter-reader agreement was assessed with Fleiss' kappa.

One hundred patients (mean age, 70 ± 14 years; 34 women) were evaluated, including 50 with GI bleeding (21 upper, 29 lower) and 50 controls. With conventional triphasic CT, sensitivity and specificity were 91.6% and 94.4%, respectively. With DECT, they were 94.4% and 96.0%, demonstrating non-inferiority within a 3% margin. Diagnostic confidence increased from 4 (IQR, 4-5) to 5 (IQR, 4-5) (p < 0.01). Mean reading time decreased from 96.3 s to 93.6 s (p < 0.01), also meeting non-inferiority. Inter-reader agreement was almost perfect (κ = 0.82). Total DLP was reduced by 20% when true non-contrast images were omitted.

DECT-derived VNC and iodine maps provide non-inferior diagnostic performance to conventional CT for GI bleeding and can replace true non-contrast imaging.

Question Eliminating true non-contrast scans from CT protocols for gastrointestinal bleeding could reduce radiation dose, but its impact on diagnostic performance remains unclear. Findings Dual-energy CT with virtual non-contrast images and iodine maps achieved non-inferior sensitivity, specificity, reading time, and diagnostic confidence compared to conventional triphasic CT. Clinical relevance Dual-energy CT with virtual non-contrast images and iodine maps can reliably replace true non-contrast scans in GI bleeding protocols, maintaining diagnostic performance while reducing radiation exposure-offering a safer and more efficient diagnostic alternative for patients.