  Recent advances in imaging techniques have enabled us to visualize lung
tumors or nodules in early-stage cancer. However, the positions of nodules can
change because of intraoperative lung deflation, and the modeling of
pneumothorax-associated deformation remains a challenging issue for
intraoperative tumor localization. In this study, we introduce spatial and
geometric analysis methods for inflated/deflated lungs and discuss
heterogeneity in pneumothorax-associated deformation. Contrast-enhanced CT
images simulating intraoperative conditions were acquired from live Beagle
dogs. Deformable mesh registration techniques were designed to map the surface
and subsurface tissues of lung lobes. The developed framework addressed local
mismatches of bronchial tree structures and achieved stable registration with a
Hausdorff distance of less than 1 mm and a target registration error of less
than 5 mm. Our results show that the strain of lung parenchyma was 35% higher
than that of bronchi, and that subsurface deformation in the deflated lung is
heterogeneous.
