Ventilation perfusion scan of the lungs.

• A. Chest X-ray
• B. VQ Scan
• C. CT Pulmonary Angiography
• D. Pulmonary function test

Answer: (B)

Ventilation-perfusion imaging directly maps both airflow and blood flow in the lungs. It uses an inhaled radiotracer to visualize ventilation and an injected radiotracer to visualize perfusion. By comparing the two images, you look for mismatches—areas that are well ventilated but poorly perfused suggest a vascular issue such as pulmonary embolism. This functional, regional assessment is what defines a VQ scan.

Chest X-ray can show gross lung abnormalities but doesn’t evaluate ventilation or perfusion distribution. CT pulmonary angiography images the blood vessels and can diagnose PE anatomically, but it isn’t a true ventilation-perfusion study. Pulmonary function tests assess overall lung function and gas exchange, not the regional distribution of ventilation and perfusion.