Technetium-99m DTPA renography and angiography in renal artery stenoses of varying severity

Thirty-five hypertensive patients, consecutively studied between 1986 and 1991, were retrospectively reviewed, to compare Technetium-99m (^99mTc) DTPA renal scanning for renal artery stenosis with angiography. Ten patients were on chronic angiotensin converting enzyme (ACE) inhibitor medication and 20 underwent angioplasty of their stenoses. In patients not on ACE inhibitors the renal scan specificity was 83%, sensitivity 82%, negative predictive value 89% and positive predictive value 74%. In the 10 patients on ACE inhibitors the specificity was 67% (relatively more stenoses of < 50% were reported in this group), sensitivity 100%, negative predictive value 100% and positive predictive value 60%. Low levels of function (<10mL/min/1.73m²) in 9 kidneys did not militate against diagnoses that correlated well with angiography. Hence, renal scanning, particularly with ACE inhibition, is efficacious in the evaluation of possible renal artery stenosis. With a mean follow-up period of 29 months after percutaneous transluminal angioplasty (PTA), four patients had clinical improvement of hypertension control. Each had pre-PTA total glomerular filtration rates (GFR) of approximately 75mL/min/1.73m². No improvement was detected in cases with pre-PTA total GFR of <50mL/min/1.73m². This may be the level of renal function below which PTA therapy or surgery will not provide benefit.