THE IMPORTANCE OF THE PERFUSION INDEX IN THE EVALUATION OF CAPTOPRIL RENOGRAPHY FOR TRANSPLANT RENAL-ARTERY STENOSIS

Severe renal artery stenosis (RAS) is a relatively uncommon complicati on following renal transplantation but is a curable cause of hypertens ion which demands reliable early diagnosis to reduce morbidity, mortal ity and graft loss. Captopril renography has been used for a number of years as a method of detecting RAS mainly in native kidneys, with onl y a few studies concerning the transplant situation. Controversy still exists as to the diagnostic accuracy of this test and as to the most appropriate interpretation criteria with which to establish a positive result. This paper reports the evaluation of 26 captopril renography investigations on hypertensive renal transplant patients with a suspec ted diagnosis of RAS. Each renogram study was correlated with an arter iogram as the 'gold standard' which was undertaken within 28 days of t he renography. A sensitivity of 92%, a specificity of 86% and an accur acy of 88% were achieved by including a consideration of the change in perfusion to the kidney between pre- and post-challenge studies. It i s concluded that captopril renography is a useful screening test for t he detection of transplant renal artery stenosis (TRAS).