Adding non-contrast and delayed phases increases the diagnostic performance of arterial CTA for suspected active lower gastrointestinal bleeding.

Objectives: When assessing for lower gastrointestinal bleed (LGIB) using CTA, many advocate for acquiring non-contrast and delayed phases in addition to an arterial phase to improve diagnostic performance though the potential benefit of this approach has not been fully characterized. We evaluate diagnostic accuracy among radiologists when using single-phase, biphasic, and triphasic CTA in active LGIB detection.

Method And Materials: A random experimental block design was used where 3 blinded radiologists specialty trained in interventional radiology retrospectively interpreted 96 CTA examinations completed between Oct 2012 and Oct 2017 using (1) arterial only, (2) arterial/non-contrast, and (3) arterial/non-contrast/delayed phase configurations.