What's your differential diagnosis, based on this scan? I'll post the correct answer in a couple of days!
Correct answer: Renal infarction. Most often a result of a clot embolus, which is most often associated with atrial fibrillation (although many patients also have diffuse atherosclerosis). Other, less likely, causes are vasculitis or a ruptured vessel. Because patients present with abdominal or flank pain that mimic other conditions, such as nephrolithiasis and pyelonephritis, the diagnosis is frequently missed or delayed.