NGP-Net: A Lightweight Growth Prediction Network for Pulmonary Nodules.

Abstract

Accurate monitoring of pulmonary nodules' growth is crucial for preventing lung cancer progression and improving patient outcomes. Yet, identifying high-risk nodules in computed tomography (CT) scans remains challenging due to subtle growth patterns, irregular follow-up intervals, and the limitations of current diagnostic tools. Existing methods often depend on single-timepoint analyses or assume fixed temporal intervals, constraining prediction to rigid scenarios. To address these limitations, we propose NGP-Net, a W-shaped architecture for dynamic nodule growth prediction from irregular longitudinal CT scans. NGP-Net introduces a Spatial-Temporal Encoding Module (STEM) that learns temporal dynamics directly from irregularly sampled data, and a dual-branch decoder that reconstructs high-fidelity nodule textures and shapes at arbitrary future timepoints. We further release a curated dataset of 378 chest CT scans from 103 patients with 226 pulmonary nodules, each followed across at least three timepoints spanning 2-64 months and annotated by seven radiologists. Extensive evaluation demonstrates that NGP-Net achieves state-of-the-art performance on this new dataset, obtaining the lowest mean square error of $\mathbf {{6}.{13} \times {{10}}^{-{3}}}$ (overall) and $\mathbf {{1}.{28} \times {{10}}^{-{4}}}$ (nodule-specific), with substantial improvements in Dice similarity coefficient ( $\mathbf {{10}.{55}\%}$ ), peak signal-to-noise ratio ( $\mathbf {{0}.{29}}$ dB), and structural similarity index ( $\mathbf {{5}.{94}\%}$ ). NGP-Net's robust and precise predictions across varied growth scenarios highlight its potential to support radiologists in clinical decision-making. The source code and dataset are publicly available at GitHub and Kaggle.