Integrated imaging approach to tumor model mice using bioluminescence imaging and magnetic resonance imaging

We developed an integrated imaging method using bioluminescence imaging (BLI) and magnetic resonance imaging (MRI) and applied it to mouse tumor monitoring. BLIs and MRIs were successively acquired from mice fixed on a transparent flat plate and were registered using three small markers. After spatial coregistration, the two-dimensional BLI was fused with all MRI slices. The accuracy of image registration was evaluated using fluorescence imaging and MRI of many markers attached to the mice. Mice were inoculated with luciferase-expressing tumor cells subcutaneously or directly into the liver, and disease progression was evaluated repeatedly by integrated BLI-MRI. Image registration was achieved with acceptable accuracy, although the registration error increased with increasing distance from the center of the imaging field and was larger in imaging the convex dorsal side of the mouse than in imaging the flat ventral side. Integrated BLI-MRI allowed longitudinal assessment of disease progression and appeared to facilitate detailed interpretation of the imaging findings. It aided the anatomic localization of lesions demonstrated by BLI and recognition of MRI abnormalities corresponding to BLI foci. Integrated BLI-MRI is feasible and appears to be a practical method for comprehensive, longitudinal assessment of disease model mice.