<Li> Arterial phase, which is particularly useful to detect for example aortic dissection . </Li> <Li> Portal venous phase </Li> <Li> Late or delayed phase </Li> <P> "Washout" is where tissue loads radiocontrast during arterial phase, but then returns to a rather hypodense state in venous or later phases . This is a property of for example hepatocellular carcinoma . </P>

Identify and briefly describe the three major phases in the ct imaging process