Radiology The most important sign of significance of renal artery stenosis on an angiogram is – A A percentage diameter stenosis > 70% B Presence of collaterals C A systolic pressure gradient > 20 mm Hg across the lesion D Post–stenotic dilatation of the renal artery 💡 Explanation The most important sign of significance of renal artery stenosis on an angiogram is – ✓ Correct Answer: B. Presence of collaterals