Interpretation of renal angiography by radiologists.

OBJECTIVE: Different radiologists may show considerable variation in their interpretation of renal angiograms. We therefore wished to establish the reliability of their interpretation. DESIGN: Assessment of the intra- and inter-observer agreement of the interpretation of renal angiograms. SETTING: Tertiary referral university hospital. PATIENTS: Hypertensive patients suspected of renovascular hypertension on clinical grounds or on the basis of renography. INTERVENTIONS: Patients were prospectively selected to undergo a renal angiography via the femoral approach. MAIN OUTCOME MEASURES: Intra- and inter-observer agreement of the degree and site of stenosis. RESULTS: The difference between two estimates of the degree of stenosis ranged from 0 to 65% for the individual readers and from 0 to 75% between two readers. When the site of greatest stenosis was in the origin of the renal artery, the intra-observer agreement kappa ranged from 0.54-0.71, the inter-observer agreement across multiple readers being 0.43. In a post hoc analysis using two different cut-off points of stenosis (50 or 70%), the intra- and inter-observer agreement was better at the 70% cut-off-point. In a subset of patients with stenosis and a renin ratio greater than 1.5, both the intra- and inter-observer agreement were much better than when all angiograms were considered. CONCLUSIONS: Assessment of the diagnostic performance of three experienced radiologists in their interpretation of renal artery angiograms indicates that the intra- and inter-observer agreement with respect to their estimates of the degree of stenosis and the site of greatest stenosis are rather poor but their diagnostic performance improves in patients with stenosis and a renin ratio greater than 1.5. There is a need for more objective assessment of renal artery lesions.