Functional testing: ACEI renography

Angiotensin-converting enzyme inhibition (ACEI) renography is the only imaging examination that tests directly for the presence of renovascular hypertension (RVH); other imaging examinations test only for the presence of renal artery stenosis (RAS). Consensus panels have recommended that ACEI renograms be interpreted as low, intermediate, or high probability for RVH. ACEI renography is highly accurate in patients with normal renal function and suspected RVH. In this patient population, the sensitivity and specificity of ACEI renography for RAS are approximately 90%; as an initial approach, angiography is not cost effective. Data from 10 studies evaluating cure or improvement in blood pressure in 291 patients undergoing revascularization showed the mean positive predictive value of ACEI renography to be 92%. When azotemic patients present with suspected RVH, as many as 50% of patients may have an intermediate probability ACEI renogram and the sensitivity of detecting RVH falls to approximately 80% even when intermediate and high probability tests are combined.