Current status of ventilation-perfusion scintigraphy for suspected pulmonary embolism

Ventilation imaging is most often performed in conjunction with lung perfusion to characterize perfusion defects as a matched, mismatched or reverse mismatched.

The optimal tracer for ventilation studies is Technegas, an ultra fine dispersion of 99mTc-labeled carbon. Despite that Technegas is not approved for use in the United States, it is used in 79% of ventilation imaging studies performed in Canada and is also commonly used in Europe. Its main advantage is greater percentage deposition in the alveolar spaces and less undesirable adherence to the central airways, compared with droplet radioaerosols.