<prompt> A 55 year old man who has been on bed rest for the past 10 days, complain of breathlessness and chest pain. The chest X-ray is normal. The next step in the investigation should beLung ventilation perfusion scanPulmonary arteriographyPulmonary venous wedge angiographyEchocardiography  <response>: This patient has a high clinical likelihood of pulmonary embolism because clinical assessment score is more than 4:-Signs symptoms of PE Breathlessness chest pain score 3.0Immobilization bed rest 3 days score 1.5So, the total score is 4.5. Therefore, imaging test should be done. CT contrast is the imaging test of choice. 