Which of the following is NOT listed as a test for pulmonary embolism?

• A. Arterial blood gas analysis
• B. D-dimer
• C. EKG: help pinpoint tachycardia and irregular heartbeat patterns
• D. MRI brain

Answer: (D)

Pulmonary embolism evaluation relies on tests that directly assess the lungs, blood clot activity, and heart response. Arterial blood gas analysis can show impaired gas exchange that may accompany PE. D-dimer is a blood marker that rises with clot formation and breakdown, helping to rule out PE when the clinical probability is low. An EKG can reveal tachycardia and signs of right heart strain, which can occur with a PE and support the suspicion. MRI of the brain, on the other hand, is used to evaluate neurological conditions like stroke or other brain disorders and does not assess the pulmonary vasculature or lung function, so it is not a standard test for diagnosing or evaluating pulmonary embolism.