Review Question - QID 8178

Figures 42a and 42b are the AP pelvis and normal chest radiographs of a 40-year-old man who was a restrained driver in a high-speed motor vehicle crash. He reports right hip pain in the emergency department. He was awake and alert, normotensive, and tachycardic. Hemoglobin was 14 gm/dL. Thoracolumbar radiographs are normal. A closed reduction of the right hip was performed and the patient was monitored in the emergency department. One hour later, he was transported to the intensive care unit and, en route, he started to report chest pain and new onset of lower extremity weakness. He was noted to be tachycardic and hypotensive. Which of the following studies should be obtained?