Deep learning-based pulmonary image registration and analysis
Creators: name: Wang, Di
Publisher: name: University of Iowa
Year: 2024
Subjects: public abstract

description: Pulmonary image registration is important because it can be used to compute lung biomechanical measures, study disease progression, and guide image surgery or radiotherapy. The learning-based pulmonary image registration method for aligning 3D breath-hold inspiration-expiration images is a challenging problem due to its large deformation magnitude, the change in CT intensity across the breathing cycle, and anatomical variations among subjects. The overall objective of this thesis is to develop and implement a deep learning-based registration algorithm to align 3D pulmonary CT images with large deformation magnitudes and investigate the regional lung mechanics and longitudinal progression pattern of chronic obstructive pulmonary disease (COPD) with image registration. We designed a fast unsupervised learning-based framework, named Population Learning followed by One Shot Learning (PLOSL), for the 3D-CT pulmonary image registration algorithm. This registration algorithm combines population learning (PL) and one-shot learning (OSL) together, which has the advantages of the PL and OSL approaches while reducing their respective drawbacks. A coarse-to-fine convolution encoder-decoder CNN architecture is used to register large and small shape features. PLOSL pulmonary image registration uses tissue volume preserving and vesselness constraints to register inspiration-to-expiration and expiration-to-inspiration pulmonary CT images.
description: The second objective of this research was to validate and evaluate the registration performance of the proposed method PLOSL in registering intra-patient chest CT images. Results demonstrated PLOSL could achieve comparable registration performance to conventional iterative image registration algorithms in terms of landmark error while preserving pulmonary topology on multiple datasets. Results also show that the proposed PLOSL can generate robust and consistent lung biomechanical measures as conventional iterative image registration algorithms across varying disease severity levels while increasing efficiency by 1.5 orders of magnitude.
description: The third aim of this research was to investigate the longitudinal progression pattern of CT-quantified outcomes of COPD at the voxel level. The correlation of regional lung function decline with emphysema and air-trapping progression was explored. Results show that regional lung function decline was correlated with increased air-trapping progression. The voxel-wise progression pattern of emphysema and functional small airway disease (fSAD) was analyzed across time as a function of the GOLD stage. Results show fSAD progression precedes the development of emphysema and the lung region affected by fSAD was at high risk of developing emphysema. Furthermore, we investigated the utility of the deep learning model for predicting the local progression of COPD for continuous progressors. Results show that CNN was able to predict the future local-level COPD progression (i.e., emphysema and air-trapping) for continuous progressors based on the earlier CTs.