To obtain a nephrogram, the radiographer would have to take a radiograph how long after injection of the contrast media?

To obtain a nephrogram, the radiographer would have to take a radiograph how long after injection of the contrast media?

• A. 30 Seconds
• B. 1 Minute
• C. 5 Minutes
• D. 10 Minutes

Answer: (B)

The nephrogram is the phase when the renal parenchyma itself is opacified by the contrast, allowing assessment of renal perfusion and contour. This happens soon after the contrast enters the kidney, before most of it has moved into the collecting system. Taking a radiograph about one minute after injection captures the cortex and medulla with enough contrast to visualize the parenchyma, which is the goal of a nephrogram. If you image at 30 seconds, you’re likely viewing the arterial Phase, where the vessels are highlighted rather than the parenchymal enhancement. Waiting several minutes (around five or more) shifts you into the excretory/pyelographic phase, where the collecting system and calyces become prominent. By ten minutes, much of the contrast has moved on, and you’d miss the nephrographic appearance. So, about one minute after injection best achieves the nephrogram phase.

The nephrogram is the phase when the renal parenchyma itself is opacified by the contrast, allowing assessment of renal perfusion and contour. This happens soon after the contrast enters the kidney, before most of it has moved into the collecting system.

Taking a radiograph about one minute after injection captures the cortex and medulla with enough contrast to visualize the parenchyma, which is the goal of a nephrogram. If you image at 30 seconds, you’re likely viewing the arterial Phase, where the vessels are highlighted rather than the parenchymal enhancement. Waiting several minutes (around five or more) shifts you into the excretory/pyelographic phase, where the collecting system and calyces become prominent. By ten minutes, much of the contrast has moved on, and you’d miss the nephrographic appearance.

So, about one minute after injection best achieves the nephrogram phase.