Imaging description

The spleen is primarily composed of red and white pulp, separated by a marginal zone of reticular cells (Figure 57.1) [1]. The red pulp consists of large numbers of blood-filled sinuses and sinusoids and is responsible for splenic filtration – filtering foreign material and damaged red blood cells. The white pulp is composed of aggregates of lymphoid tissue responsible for the immunologic function of the spleen [1]. The enhancement dynamics of the spleen are largely attributed to the different blood flow rates through these two tissue structures [2]. If the spleen is imaged in an early arterial phase, the parenchyma can appear heterogeneous as patches of unenhanced white pulp contrast with normally enhanced red pulp.

Three principal patterns of splenic enhancement have been described – archiform, focal, and diffuse. Archiform patterns typically appear as alternating bands of high and low attenuation, a ring-like pattern, or a zebra-stripe pattern (Figure 57.2) [3]. Focal lesions appear as a single area of low attenuation (Figure 57.3). Diffuse enhancement appears as a mottled pattern throughout the splenic parenchyma.