A method for mapping regional oxygen and CO2 transfer in the lung

• We present a method to map pulmonary O2 and CO2 transfer rates in three dimensions.
• The method is illustrated using PET/CT data from a healthy subject and an asthmatic.
• We present sensitivity analyses of errors in imaging data and in global variables.
• Gas transfer maps may yield valuable insights into lung function in health and disease.

This paper presents a novel approach to visualizing regional lung function, through quantitative three-dimensional maps of O2 and CO2 transfer rates. These maps describe the contribution of anatomical regions to overall gas exchange and demonstrate how transfer rates of the two gas species’ differ regionally.An algorithm for generating such maps is presented, and for illustration, regional gas transfer maps were generated using values of ventilation and perfusion imaged by PET/CT for a healthy subject and an asthmatic patient after bronchoprovocation.In a sensitivity analysis, compartment values of gas transfer showed minor sensitivity to imaging noise in the ventilation and perfusion data, and moderate sensitivity to estimation errors in global lung input values, chiefly global alveolar ventilation, followed by cardiac output and arterial-venous O2 content difference.Gas transfer maps offer an intuitive display of physiologically relevant lung function at a regional level, the potential for an improved understanding of pulmonary gas exchange in health and disease, and potentially a presurgical evaluation tool.

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