When does the portal-venous phase occur after a bolus injection?

The portal-venous phase typically occurs approximately 60 seconds after a bolus injection of contrast material during a CT scan. This phase is characterized by optimal enhancement of the liver's vascular supply primarily through the portal vein, which brings blood from the gastrointestinal tract to the liver. Achieving this phase is crucial for imaging structures that rely on portal circulation, as it provides a clear contrast difference that aids in the detection of lesions, liver abnormalities, and vascular structures.

The timing of this phase is based on the dynamics of contrast flow through the vascular system following injection. In most protocols, 60 seconds is established as a standard time point to capture the enhancement that will help delineate the anatomy and pathologies in the abdomen. Understanding the timing of these phases is essential for obtaining optimal imaging results during abdominal CT scans.