Renal Artery Stenosis
| % Stenosis | Peak velocity (cm/sec) | Renal PSV to aortic PSV ratio (RAR) |
| Normal | <180 | <3.5 |
| <60% | >=180 | <3.5 |
| 60-99% | >=180 | >=3.5 |
| Occlusion | No color flow |
Renal artery resistive index: Normal is about 0.6. 0.7 is used as the upper limite of normal.
High RI: renal artery stenosis (if measured upstream from the stenosis) , ureteric obstruction, extreme hypotension, very young children, perinephric fluid collection, medical renal disease.
High RI in transplant: acute tubular necrosis (ATN), acute or chronic transplant rejection, renal vein thrombosis, drug toxicity, renal artery stenosis (if measured upstream from the stenosis), ureteric obstruction, perinephric fluid collection.
Mesenteric Artery Stenosis: (more than 70% stenosis)
Celiac Artery: PSV > 200 cm/s.
SMA: PSV > 275 cm/s.
IMA: PSV > 200 cm/s.