Imaging in Aerosol Medicine

Imaging techniques have been used extensively to study the delivery of inhaled medications. Deposition scintigraphy involves the quantification of deposited aerosol dose and is performed using 2-dimensional planar or 3-dimensional positron emission tomography (PET) or single-photon-emission computed tomography (SPECT) imaging techniques. Planar techniques have an extensive history of use, and quantification methods are well established. SPECT and PET techniques can provide better dose localization, but quantification is more complex, and the techniques are in more limited use. Aerosols have also been used to deliver radiopharmaceutical probes for the imaging of lung physiology. These studies include measurements of ventilation, mucus and cough clearance, and, more recently, liquid absorption in the airways. Clearance measurements have been used to assess therapeutic response in conditions such as cystic fibrosis. Future directions in aerosol-based imaging are likely to include use of novel probes to measure new physiological processes in the lung, more thorough integration of anatomical imaging, and use of multiple probes to simultaneously image drug and disease or interacting physiological processes.