Hemorrhages can be easily distinguished from veins if SWI is performed both before and after administration of contrast agent. Blood vessels will change their signal intensity due to the contrast agent, but signal intensity from hemorrhage will not change. Fig (left) Precontrast SWI shows a small hemorrhage inside the tumor (arrow). (right) In postcontrast SWI, a new hypointense signal intensity appears after contrast agent injection, which indicates the presence of intratumoral vessels; the signal intensity from the hemorrhage inside the tumor remains unchanged (arrow). Mittal et al. 2009