Motion Compensation in Pulmonary Fluorescence Lifetime Imaging: An Image Processing Pipeline for Artefact Reduction and Clinical Precision

Goal: This study introduces Temporal Reliability and Accuracy via Correlation Enhanced Registration (TRACER), a novel image processing pipeline that addresses motion artefacts in real-time Fluorescence Lifetime Imaging (FLIm) data for in-vivo pulmonary Optical Endomicroscopy (OEM). Its primary objective is to improve the accuracy and reliability of FLIm image sequences. Methods: The proposed TRACER pipeline comprises a comprehensive sequence of pre-processing steps and a novel registration approach. This includes the removal of uninformative frames and motion characterisation through dense optical flow, followed by a tracking-based Normalised Cross Correlation image registration method leveraging Channel and Spatial Reliability Tracker for precise alignment. Results: The complete TRACER pipeline delivers significant performance improvements, with 20% to 30% enhancement across different metrics for all tested registration methods. In particular, the unique TRACER registration approach outperforms state-of-theart methods in image registration performance and achieves an order-of-magnitude faster runtime than the next best-performing approach. Conclusion: By addressing motion artefacts through its integrated pre-processing and novel registration strategy, TRACER offers a robust solution that ensures improved image quality and real-time feasibility for FLIm data processing in in-vivo pulmonary OEM.