Not all cases of renal artery stenosis will cause renovascular hypertension. Some patients will show no response to angioplasty or stenting. ACE inhibition renography can be used to determine which patients with renal artery stenosis could benefit from intervention. 

High probability criteria for renovascular hypertension: 

• 10% decrease in differential (split) function (i.e. 50/50 to 60/40)
• retained cortical activity at 20 minutes differing from the contralateral kidney by more than 20%
• delay in time to peak activity in the affected kidney of more than 2 minutes when compared to the baseline study or unaffected kidney