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