THE PLACE OF RENAL SCINTIGRAPHY IN THE DIAGNOSIS OF RENAL-ARTERY STENOSIS - 15 YEARS OF CLINICAL-EXPERIENCE

Background: Renal scintigraphy with radiolabeled pentetic acid (diethy lenetriamine pentaacetic acid [DTPA]) or, more recently, mertiatide (m ercaptoacetyltriglycine [MAG(3)]), with or without captopril challenge , is widely recommended as a diagnostic test for renal artery stenosis . Objectives: To address (1) whether the diagnostic accuracy has been improved by the use of captopril and the introduction of mertiatide an d (2) whether a renal scan that shows abnormalities is a useful criter ion to select patients for renal arteriography. Patients and Methods: A standard diagnostic protocol, using both scintigraphy and arteriogra phy, was followed in 505 consecutive high-risk hypertensive patients w ho were evaluated for renovascular hypertension at the University Hosp ital Dijkzigt, Rotterdam, the Netherlands, from 1978 to 1992. Results: Renal artery stenosis (greater than or equal to 50%) was present in 2 63 patients. When the single-kidney fractional uptake was used as a di agnostic criterion, a specificity of 0.90 was obtained at a cutoff val ue of 35% for the worst kidney in scintigraphy using pentetic acid wit hout captopril challenge (n=225) and at a cutoff value of 37% after ca ptopril challenge (n=280). This was associated with sensitivity levels of 0.65 and 0.68, respectively. The difference between the uptake of pentetic acid with and without captopril challenge in the 85 patients who were studied under both circumstances was no more accurate as a pr edictor of renal artery stenosis. In the 93 patients who were studied with mertiatide as well as with pentetic acid, both after captopril ch allenge, the diagnostic accuracy was no better with mertiatide than wi th pentetic acid; mertiatide failed to offer any advantage not only wh en the single-kidney fractional uptake was used as a criterion, but al so with the use of other scintigraphic parameters leg, time to peak, t ime to pyelum, overall shape of renographic curve, and kidney size). C onclusions: The diagnostic accuracy of renal scintigraphy has not been improved by the introduction of mertiatide or by the use of captopril . The usefulness of scintigraphy as a diagnostic test for the presence of renal artery stenosis remains questionable. The physician will alw ays confront either a substantial number of arteriograms that do not s how abnormalities when renal scintigraphy is omitted as a screening st ep or a substantial number of missed diagnoses when a renal scan that shows abnormalities is used as a prerequisite for arteriography.