Prospective Study on Captopril Renography in Hypertensive Patients

Abstract

Six hundred and sixty-seven hypertensive patients were analyzed by captopril-enhanced scintigraphy. If time to reach maximal activity (T_max) was ≧ 5 min using ^99mTc-diethylenetriaminepentaacetic acid (DTPA) or ≧ 3 min with ¹²³I-oiodohippurate (OIH) and ^99mTc-mercaptoacetyltriglycine (MAG3) and washout time ≧ 15 min, a control study with nifedipine was performed. If the difference between T_max under captopril and nifedipine premedication was ≧ 5 min with ^99mTc-DTPA or ≧ 3 min with ¹²³I-OIH and ^99mTc-MAG3, the renogram was defined highly suggestive of renovascular hypertension. In the evaluation of bilateral abnormalities an additional parameter was considered, i.e. the presence of functional asymmetry of the emuntories susceptible of partial reversal in the control study under nifedipine. Based on these criteria, 58 out of 667 (8.7%) scintigrams were found to be abnormal. Thirty-five of these 58 patients and 32 of the remaining 609 scintigraphically negative cases underwent additional arteriographic examination. A renal vascular stenosis ≧ 50% was found in 33 out of 35 (94.2%) patients with positive scintigraphy and in 3 out of 32 patients with negative scintigraphy. By examining results of the 67 patients undergoing arteriography, the sensitivity of captopril-enhanced scintigraphy was estimated to be 91.6 %, with a specificity of 9 3.5 %, an accuracy of 92.5 %, and predictive values of a positive or negative result of 94.2 and 90.6%, respectively. By restricting analysis to bilateral stenosis, sensitivity was found to be 76.9%. Postexamination of 16 patients undergoing revascularization by surgery or percutaenous transluminal renal angioplasty reflected the expected results with a substantial shortening in T_max and T75 in the responsive cases.

Interpretation of captopril renography using artificial neural networks

“…The results are similar to those of human experts shown in earlier studies (Fommei et alm 1993, Mann et al, 1991, Gijsbert et al, 1991, Setaro et al, 1991, Roccatello et al, 1992, i.e. sensitivity and specificity in the region of 90 % respectively.…”

Radionuclides in Nephrourology, Part 2: Pitfalls and Diagnostic Applications

“…In an attempt to circumvent this problem, other investigators have used the more stringent standard of a stenosis greater than 70%. Although good results have been reported using RAS as the gold standard (70), not surprisingly, the sensitivity and specificity of ACE inhibition renography is improved when the gold standard is the response to revascularization rather than the anatomic presence of RAS (50,65–69). …”

The diagnosis of renovascular hypertension: the role of captopril renal scintigraphy and related issues

“…In contrast, in patients with RVHT and plasma creatinine values >_ 160 btM, the increased RCA observed after ACE inhibition decreased in the baseline renogram [62]. Other similar excretory indexes, such as washout time (T 75%) or the asymmetrical reversal of bilaterally abnormal renograms with 123I-hippuran or 99mTc-MAG 3, can be used in patients with renal impairment to discriminate RVHT from various other intrinsic renal diseases in hypertension [101].…”