Regional lung ventilation from volumetric CT scans using image warping functions

We describe a unique method to determine regional lung ventilation non-invasively. In this study, lungs of two sheep were imaged utilizing a multi-detector row CT while maintaining the lungs at different lung inflations in prone and supine positions. Analysis of cross-sections was then performed on the subjects. We made use of a warping function to map lung regions at different lung volumes based on a set of user-defined landmarks, and validated the warping functions using a set of implanted metal markers. The change in Hounsfield units within smaller lung regions was then used to calculate the percentage air content and regional ventilation.