Renogram Curves

1. General
1. There are three portions to a renogram curve



1. A - Vascular (flow phase) - Shows blood flow and initial uptake
2. B - Cortical transit (tissue-function phase) - Peaks at 3-5 minutes
3. C - Excretory (drainage phase) - T1/2 should be less than 10 minutes
4. Time per phase is important in assessing normal/abnormal renal function
2. Delay in any part of the curve indicates a problem with that aspect of the kidney
1. Vascular
1. What would cause delayed uptake?
2. What would cause little or no activity?
2. Cortical transit
1. What would cause the curve to have an extended cortical transit time?
2. What would cause the curve never to have a peak?

3. Components that affect this phase - a variation of cortical transit time is noted with different radiopharmaceuticals. Other aspects that would effect cortical transit would include: age, renal transplant, and dehydration
3. Excretory phase
1. What would cause an extended T1/2 or no T1/2?
2. What should be administered to confirm disease?
4. What would cause a delay in all three aspects of the curve?
2. A look at some curves


1. First, let us look at a normal curve (above)
   1. There is a short vascular phase
   2. Cortical transit that lasts no more than several minutes
   3. The T1/2 of both Rt and Lt kidneys occur within 10 minutes
      

2. The next example considers renal obstruction and the concern is to determine when a complete or partial obstruction may be present
   1. Blue line represents a normal time-activity curve of the kidneys
   2. Following the red line to determine obstruction.
   3. When lasix is given does the slope turn negative or stays positive?
   4. Click here if you need see the difference between a positive and negative slope
   5. Following the orange lines where the T1/2 is less than 10 minutes (total 30 minutes) then there is no obstruction
   6. However, if the T1/2 is between 10 to 20 minutes (total 30 to 40 minutes) then there is partial objection
   7. If the red line continues a positive slope, then there is total obstruction

 


3. Here is an actual time-activity curve that shows total obstruction. Note that even after Lasix is administered the curve continues to build



4. Example of what a hydroureter (ureter blockage) looks like. The above is a similar example from the previous curve showing no cortical transit or excretion phase

    


5. The above is an example of ATN following a renal transplant. There is no clear definition of cortical transit or excretion phase.

6. The above is an example of renal nephrectomy or a non-functioning kidney.



7. What does a time activity-curve look like as the kidney continues to fail over time? Several key points you should note
   1. As renal failure continues all three phases of the time-activity curve are extended.
   2. Purple goes to brown goes to red in the different curves are an example of the kidneys progressively getting worse.
   3. Red also indicates total obstruction
   4. Blackline indicates total renal failure


8. Three more examples of renal curves and the related images. What are your thoughts as to what might be going right/wrong?

9. Compare the role of lasix and relate this to renal obstruction

10. Can you tell the effects of an Ace Inhibitor?

11. Assess the curves. Compare the right kidney to the left.