Saline flush during contrast medium administration

The saline flush during contrast medium administration otherwise known as a saline chaser is a secondary injection following the administration of contrast medium via a power injector. It is used in both CT and MRI.

The primary purpose of the saline chaser is to ‘push’ the otherwise unused contrast agent in the peripheral vessels and connecting tubing. This mechanism allows for a reduction in contrast medium volume during and a decrease in the bolus artifact seen in the superior vena cava and brachiocephalic vein during CT contrast examinations. The saline ‘push’ also modifies the shape of the injected contrast bolus resulting in a steep drop in contrast enhancement due to the lack of lingering contrast arriving from the peripheries.