A 3D-CNN model with CT-based parametric response mapping for classifying COPD subjects

Thao Thi Ho, Taewoo Kim, Woo Jin Kim, Chang Hyun Lee, Kum Ju Chae, So Hyeon Bak, Sung Ok Kwon, Gong Yong Jin, Eun Kee Park, Sanghun Choi

Research output: Contribution to journalArticlepeer-review

Abstract

Chronic obstructive pulmonary disease (COPD) is a respiratory disorder involving abnormalities of lung parenchymal morphology with different severities. COPD is assessed by pulmonary-function tests and computed tomography-based approaches. We introduce a new classification method for COPD grouping based on deep learning and a parametric-response mapping (PRM) method. We extracted parenchymal functional variables of functional small airway disease percentage (fSAD%) and emphysema percentage (Emph%) with an image registration technique, being provided as input parameters of 3D convolutional neural network (CNN). The integrated 3D-CNN and PRM (3D-cPRM) achieved a classification accuracy of 89.3% and a sensitivity of 88.3% in five-fold cross-validation. The prediction accuracy of the proposed 3D-cPRM exceeded those of the 2D model and traditional 3D CNNs with the same neural network, and was comparable to that of 2D pretrained PRM models. We then applied a gradient-weighted class activation mapping (Grad-CAM) that highlights the key features in the CNN learning process. Most of the class-discriminative regions appeared in the upper and middle lobes of the lung, consistent with the regions of elevated fSAD% and Emph% in COPD subjects. The 3D-cPRM successfully represented the parenchymal abnormalities in COPD and matched the CT-based diagnosis of COPD.

Original languageEnglish
Article number34
JournalScientific Reports
Volume11
Issue number1
DOIs
StatePublished - Dec 2021

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