How do you approach the workup of a patient with a large focal wedge-shaped cortical swelling on CT concerning for renal infarct, but with a normal echocardiogram showing no thrombus or vegetation?  

This would depend on the clinical setting - is this someone presenting with signs or symptoms suggesting acute ischemic kidney disease, or an incidental finding on the CT? My first step would be to determine if this is actually a renal infarct by imaging. Either CTA or MRA, or nuclear renogram would...