Modality-agnostic, patient-specific digital twins modeling temporally varying digestive motion
Journal:
arXiv
Published Date:
Jul 2, 2025
Abstract
Objective: Clinical implementation of deformable image registration (DIR)
requires voxel-based spatial accuracy metrics such as manually identified
landmarks, which are challenging to implement for highly mobile
gastrointestinal (GI) organs. To address this, patient-specific digital twins
(DT) modeling temporally varying motion were created to assess the accuracy of
DIR methods. Approach: 21 motion phases simulating digestive GI motion as 4D
sequences were generated from static 3D patient scans using published
analytical GI motion models through a semi-automated pipeline. Eleven datasets,
including six T2w FSE MRI (T2w MRI), two T1w 4D golden-angle stack-of-stars,
and three contrast-enhanced CT scans. The motion amplitudes of the DTs were
assessed against real patient stomach motion amplitudes extracted from
independent 4D MRI datasets. The generated DTs were then used to assess six
different DIR methods using target registration error, Dice similarity
coefficient, and the 95th percentile Hausdorff distance using summary metrics
and voxel-level granular visualizations. Finally, for a subset of T2w MRI scans
from patients treated with MR-guided radiation therapy, dose distributions were
warped and accumulated to assess dose warping errors, including evaluations of
DIR performance in both low- and high-dose regions for patient-specific error
estimation. Main results: Our proposed pipeline synthesized DTs modeling
realistic GI motion, achieving mean and maximum motion amplitudes and a mean
log Jacobian determinant within 0.8 mm and 0.01, respectively, similar to
published real-patient gastric motion data. It also enables the extraction of
detailed quantitative DIR performance metrics and rigorous validation of dose
mapping accuracy. Significance: The pipeline enables rigorously testing DIR
tools for dynamic, anatomically complex regions enabling granular spatial and
dosimetric accuracies.
