Positron emission tomography imaging of regional lung function.

Area of Science:

• Pulmonary physiology
• Medical imaging
• Nuclear medicine

Background:

• Assessing regional pulmonary perfusion and ventilation is crucial for understanding lung function.
• Positron emission tomography (PET) offers advanced imaging capabilities.
• Nitrogen-13 (13N2) has unique properties for pulmonary kinetic studies.

Purpose of the Study:

• To describe the methodology of PET imaging for regional pulmonary perfusion and ventilation using 13N2.
• To highlight insights into the pathophysiology of acute lung injury and asthma gained through this technique.

Main Methods:

• Intravenous infusion of 13N2 in saline during a short apnea to assess regional perfusion and shunt.
• Modeling pulmonary kinetics of 13N2 to obtain robust estimates.
• Modeling 13N2 washout after resuming breathing to measure regional ventilation.
• Inhalation of 13N2 to measure regional gas content and dead space ventilation.

Main Results:

• 13N2 accumulates in alveolar airspace proportional to regional perfusion during apnea due to low solubility.
• Non-aerated regions do not retain infused 13N2, allowing for shunt estimation.
• Regional ventilation is accurately measured by modeling 13N2 washout.
• The technique provides valuable data on regional gas exchange.

Conclusions:

• PET imaging of 13N2 kinetics is a novel functional imaging technique for pulmonary assessment.
• This method enhances understanding of the pathophysiology of various pulmonary diseases, including acute lung injury and asthma.