CPT-Interp: Continuous sPatial and Temporal Motion Modeling for 4D Medical Image Interpolation

TL;DR

CPT-Interp introduces a novel neural approach inspired by fluid mechanics for continuous 4D medical image interpolation, improving accuracy and speed while reducing data requirements.

Contribution

It presents a continuous motion modeling method using implicit neural representation that bridges spatial and temporal domains for 4D medical images.

Findings

Outperforms existing methods in accuracy and speed

Operates as a training-free, case-specific optimization

Effectively models continuous anatomical motion

Abstract

Motion information from 4D medical imaging offers critical insights into dynamic changes in patient anatomy for clinical assessments and radiotherapy planning and, thereby, enhances the capabilities of 3D image analysis. However, inherent physical and technical constraints of imaging hardware often necessitate a compromise between temporal resolution and image quality. Frame interpolation emerges as a pivotal solution to this challenge. Previous methods often suffer from discretion when they estimate the intermediate motion and execute the forward warping. In this study, we draw inspiration from fluid mechanics to propose a novel approach for continuously modeling patient anatomic motion using implicit neural representation. It ensures both spatial and temporal continuity, effectively bridging Eulerian and Lagrangian specifications together to naturally facilitate continuous frame interpolation. Our experiments across multiple datasets underscore the method's superior accuracy and speed. Furthermore, as a case-specific optimization (training-free) approach, it circumvents the need for extensive datasets and addresses model generalization issues.