Imaging description

On contrast-enhanced images, foci of high density that do not conform to the shape, location, and enhancement of normal parenchyma usually represent active bleeding. Occasionally, a similar appearance can be seen with islands of perfused parenchyma surrounded by hematoma (Figure 50.1).

Active arterial or venous extravasation presents with foci of high density on portal venous phase images, corresponding to contrast-enhanced blood that has extravasated from a disrupted blood vessel. If this material is significantly denser than parenchyma, then contrast extravasation can be diagnosed at this time. However, if this material is similar in density to enhancing parenchyma, delayed images are necessary to make the diagnosis. Delayed imaging findings diagnostic of active extravasation include persistence or additional accumulation of high-density contrast and/or diffusion of contrast into the surrounding spaces.

Islands of perfused parenchyma surrounded by hematoma will generally follow the enhancement pattern of normal parenchyma. They enhance on portal venous phase images, and wash out on delayed phase images. If there is contusion of these fragments, the enhancement pattern may be different, and can match that of contused parenchyma within an organ. Whether contused or not, their appearance will be different from that seen with significant extravasations.