A Preclinical Co-Registration Pipeline for MRI and PET/CT: Enabling Multi-tracer Multiparametric PET-CT/MRI in Solid Tumors

Motivation: Robust preclinical multimodal image registration must be developed to provide rich multiparametric data to noninvasively reveal biological treatment-induced tumor alterations. Goal(s): Establish a pipeline to enable multimodal registration of semi-rigid, subcutaneous tumors in preclinical models to evaluate multi-tracer multiparametric PET/CT-MR metric alterations. Approach: Utilizing a breast cancer murine model, a custom-designed mouse couch, augmented with an injectable liquid fiducial marker, was assessed for MR-CT co-registration, facilitating the development of a registration pipeline. Results: Post-registration tumor segmentation performed independently across modalities yielded high Dice Similarity Coefficient scores (0.92-0.95), indicating accurate tumor alignment, and enabling preliminary multiparametric voxel-wise comparisons of multimodal imaging metrics. Impact: Preclinical imaging with our registration pipeline enables for biological treatment-induced characterization of subcutaneous tumors through sequential multi-tracer multiparametric PET/CT-MR.