A 55-year-old female undergoes a hip replacement after a fall. Two days post op she develops sudden shortness of breath and tachycardia. On examination, she is tachypneic with a heart rate of 120. Her blood pressure is 120/57. Blood gas reveals a pH of 7.38, PCO2 35, PO2 72, and bicarbonate of 23. Duplex of the extremities reveals a large clot in the iliofemoral veins. What of the following is most likely to be found on a chest radiograph?