Ventilation and perfusion scintigraphy (VQ scans) provide a relatively non-invasive evaluation of lung function. They indicate the relative blood flow to each lung and allow a quantitative assessment of the perfusion of each lung segment. They can detect areas of abnormal aeration and demonstrate air trapping. However, VQ scanning gives relatively poor anatomical detail of the lungs and so is commonly used in conjunction with other radiological modalities, most notably the chest X-ray. VQ scans have been utilized for a large range of pathological conditions including congenital cardiac and lung abnormalities, suspected pulmonary emboli, the assessment of childhood diseases, including cystic fibrosis, bronchopulmonary dysplasia and asthma.