Figure 18b. Surgical clip artifact mimicking stenosis in a 56-year-old man who presented with renal dysfunction and hypertension. The patient had undergone renal transplantation 9 years earlier. (a) MPVR MR angiogram demonstrates an area of apparent narrowing in the main renal artery (arrow). (b) Subsequent contrast-enhanced MR angiogram demonstrates a widely patent main renal artery with a clip at the site of the MR imaging pseudostenosis (arrowhead).