Investigation of choice in pulmonary embolism: March 2009

Ans. C: Chest CT Helical CT scanners and multidetector CT, with intravenous contrast which allow rapid coverage of the chest with high resolution, have become increasingly used as the examination of choice for diagnosing. Advantages in adults and children have included the identification of other causes for the clinical presentation when pulmonary embolism is not present. Thrombi within the pulmonary vessels can be demonstrated. It is considered to be more cost-effective because fewer indeterminate and nondiagnostic studies are needed. Additionally, central nonobstructing emboli are clearly seen with CT, but they would not be demonstrated with perfusion imaging. Disadvantages of CT include the radiation dose, which is known to be associated with a small but significant risk of neoplasia.