Physiology for the pulmonary functional imager

- An understanding of the relevant pulmonary physiology is crucial to functional lung imaging.
- Spatial resolution for pulmonary functional imaging can be substantially less than that used for anatomic/clinical imaging.
- Regional deformation of the lung under the influence of gravity significantly affects the measurement of pulmonary perfusion.
- Large vessels identified on perfusion imaging do not represent local blood flow.
- Pulmonary diseases are typically characterized by a change in the matching of ventilation and perfusion.

As pulmonary functional imaging moves beyond the realm of the radiologist and physicist, it is important that imagers have a common language and understanding of the relevant physiology of the lung. This review will focus on key physiological concepts and pitfalls relevant to functional lung imaging.