What phase occurs between 70 and 90 seconds after the injection of a contrast agent in CT imaging?

The phase that occurs between 70 and 90 seconds after the injection of a contrast agent in CT imaging is the nephrographic phase. During this phase, the contrast material is primarily concentrated within the renal parenchyma, which enhances the visibility of the kidneys and surrounding structures. This timing is crucial for adequately assessing renal function and pathology, as the kidneys are actively filtering and excreting the contrast material during this period, providing optimal visualization of renal tissue.

In this context, the nephrographic phase is significant for evaluating various renal conditions, such as tumors, cysts, or signs of renal failure. The enhancement of the renal parenchyma can be effectively visualized in this timeframe, allowing for clear differentiation between normal and abnormal findings.

Other phases, such as the arterial phase, occur shortly after contrast injection and are characterized by arterial enhancement, while the venous phase follows shortly after and provides visualization of structures receiving blood through venous circulation. The excretory phase takes place after the nephrographic phase, where the contrast material is actively being excreted into the renal collecting system. Thus, understanding the timing and characteristics of these phases is essential for optimal imaging and diagnosis in CT studies.