V/Q Scan (Both Lung Perfusion and Lung Ventilation)

A V/Q (ventilation–perfusion) scan is a nuclear medicine test that evaluates airflow and blood flow in the lungs. It uses a small inhaled radioactive gas or aerosol for ventilation images and an injected radiotracer for perfusion images. Comparing the two reveals mismatched areas that suggest pulmonary embolism. It’s noninvasive, relatively low‑radiation, and used when CT angiography is unsuitable.

Ventilation is the movement of air into and out of the lungs and alveoli, bringing oxygen in and removing carbon dioxide. Perfusion is the flow of blood through pulmonary capillaries around alveoli, delivering deoxygenated blood for gas exchange and carrying away oxygenated blood. Effective gas exchange requires matching ventilation and perfusion; mismatches reduce oxygen uptake and can cause low blood oxygen.

In India, a V/Q (ventilation–perfusion) lung scan typically costs between ₹3,000 and ₹12,000. Prices vary by city and facility (government vs private), whether the radiotracer and report are included, and any hospital admission or additional imaging. Public hospitals may charge much less or offer subsidized rates; private and corporate centres generally charge higher fees.

A normal V/Q (ventilation–perfusion) scan shows uniform, matched ventilation and perfusion throughout both lungs with no segmental or larger perfusion defects or mismatched areas. Perfusion mirrors ventilation on imaging, indicating preserved blood flow and air distribution. This pattern carries a very low probability of pulmonary embolism and is considered a normal study.

A ventilation–perfusion (V/Q) scan usually takes about 30–60 minutes for the imaging itself. The ventilation and perfusion phases each take roughly 15–30 minutes, with short waits between. Allow 1–2 hours for the whole appointment to include registration, explanations and any preparation. If you have limited mobility or breathing difficulty, discuss arrangements with the imaging department.

The normal ventilation–perfusion (V/Q) ratio is about 0.8 (approximately 4 L/min alveolar ventilation to 5 L/min pulmonary blood flow). This reflects overall matching in the healthy lung but varies regionally: the apex has a higher V/Q (~3.0) and the base a lower V/Q (~0.6) due to gravity-dependent differences in ventilation and perfusion.