Renal scan

Tc-DTPA

• Inject 5-15 mCi
• Cleared by glomerular filtration
• Used to measure GFR (normal is 125mL/min)
• May underestimate by 5-10% due to protein bond DTPA
• Brief nephrogram phase so not used for cortical imaging

Tc-MAG3

• Inject 5-15 mCi
• Cleared by tubular secretion (95%)
• Used to assess tubular function
• Protein bound
• Can measure effective renal plasma flow (ERPF)

Tc-DMSA

• Binds renal tubules for cortical imaging
• Evaluate for scar in pediatric population
• Pinhole or SPECT used

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Blood Flow (perfusion) - decreased perfsion is nonspecific and it can be flow related or secondary to poor kideny function with the exception of ATN where blood flow is preserved with poor function

Clearance - difficult to get standards becasue must exclude calyces

Diuretic Renogram

• Emptying T1/2 of <10 min is normal
• Emptying T1/2 of >20 min is abnormal

Captopril Scan

• Use ACE inhibitor which blocks efferent vasoconstriction, decreases GFR and induce renal insufficiency
• Monitor BP
• Won't work if renal function is already poor
• Unilateral is evident, bilateral is more difficult, may have to do a baseline scan

Transplant Kidney

• Mostly to evaluate perfusion
• ATN - prolonged accumulation of radiatracer with normal blood flow
• Rejection - poor perfusion

Tc-MAG3 Renal Scan

Blood Flow	Pre Lasix with Delayed Clearance on right
Post Lasix with washout	Spot images with Gallbladder uptake