Typical arterial phase appearance of the spleen. This striking wave-like, somewhat psychedelic, pattern of enhancement is a product of the unique splenic vascular anatomy, specifically the sinusoids within the red pulp. Assessment for splenic laceration and subcapsular hematoma can sometimes be difficult during the arterial phase which is why the organ is often covered in both the arterial and portal venous phases. Recently, trauma CT protocols involving single scan combined arterial phase and portal venous phase imaging of the chest, abdomen and pelvis have helped reduce patient radiation dose by allowing the spleen to be scanned only once.