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CT- and MRI-Aided Fluorescence Tomography Reconstructions for Biodistribution Analysis
Sarah Schraven1, Ramona Brück, Stefanie Rosenhain
1From the Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany (S.S., R.B., S.R., T.L., D.H., W.L., F.G., F.K.); Institute of Molecular Medicine, RWTH Aachen University, Aachen, Germany (H.N., O.P.); Gremse-IT GmbH, Aachen, Germany (S.R., F.G.); Department for Diagnostic and Interventional Radiology, RWTH Aachen University, Aachen, Germany (T.L.); Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany (F.K.); and Fraunhofer MEVIS, Institute for Medical Image Computing, Aachen, Germany (F.K.).
This study introduces a novel trimodal imaging approach combining computed tomography-magnetic resonance imaging-fluorescence tomography (CT-MRI-FLT) for enhanced biodistribution tracking. The new method improves fluorescence signal assignment and pharmacokinetic analysis accuracy.
Area of Science:
- Biomedical imaging
- Optical fluorescence imaging
- Multimodal imaging
Background:
- Optical fluorescence imaging tracks biodistribution of labeled agents.
- Hybrid computed tomography-fluorescence tomography (CT-FLT) offers anatomical context but suffers from limited soft tissue contrast.
- Magnetic resonance imaging (MRI) provides superior soft tissue characterization, potentially improving fluorescence imaging accuracy.
Purpose of the Study:
- To establish and evaluate a hybrid CT-MRI-FLT approach for whole-body imaging.
- To compare the performance of CT-MRI-FLT with conventional CT-FLT.
- To assess the impact of MRI on fluorescence reconstruction and quantification accuracy.
Main Methods:
- Developed and implemented a trimodal CT-MRI-FLT imaging system.
- Utilized a fat-water-separated mDixon sequence for MRI acquisition.
- Co-registered CT, MRI, and FLT data using fiducial markers for accurate fusion.
- Validated the approach using phantoms, ex vivo mouse samples, and in vivo biodistribution studies with fluorescent immunoglobulins.
Main Results:
- Successfully fused CT and MRI data, demonstrating good segmentation agreement.
- CT-MRI-FLT enabled more detailed soft tissue characterization compared to CT-FLT alone.
- While fluorescence reconstructions were comparable in dead mice, MRI improved organ segmentation and signal assignment in vivo.
- MRI facilitated visualization of additional organs like the gallbladder, thyroid, and brain, leading to more differentiated conclusions.
Conclusions:
- Whole-body CT-MRI-FLT represents a novel trimodal imaging approach.
- This method enhances the accuracy of fluorescence signal assignment.
- The improved accuracy significantly benefits pharmacokinetic analyses and overall understanding of biodistribution.
