Psma pet ct scans align while preserving tumor measurements
PET Quantification-Preserving Registration for Longitudinal Whole-Body PSMA PET/CT
Computer Vision and Pattern Recognition
Summary
Tracking changes in cancer using PET/CT scans requires aligning images taken at different times. The authors improved an existing method to better register whole-body scans while keeping important tumor measurements accurate. They used special constraints to keep the size and activity of tumors consistent in the images. Their approach performed well in tests and the code is available for others to use.
What this means in practice
- •For medical imaging teams: Align longitudinal PSMA PET/CT scans accurately while preserving tumor size and metabolic activity for monitoring cancer progression or treatment response.
- •For radiation therapy planners: Improve the accuracy of tumor targeting by registering whole-body scans over time without distorting key tumor biomarkers.
Authors
Fryderyk Kögl, Anna Reithmeir, Daniel M. Lang, Emily Chan, Rickmer Braren, Julia A. Schnabel
Abstract
We adapt the diffeomorphic coarse-to-fine LapIRN architecture for longitudinal whole-body PSMA PET/CT registration in the Learn2Reg 2026 PSMAReg challenge. The method combines affine pre-registration, multi-modal deformable registration, and test-time instance optimization. We further introduce PET biomarker preservation losses for metabolic tumor volume (MTV) and total lesion glycolysis (TLG), including Jacobian-based constraints, and a per-structure rigidity regularization for skeletal structures. The submitted configuration achieved 81.0% DSC and 6.17 mm HD95, with MTV and TLG errors of 3.3% and 3.3%, respectively, on our evaluation protocol. Code is available at https://github.com/koegl/psmareg.