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Updated: Aug 16, 2026
Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT
Published on: November 23, 2012
Registration of [18F]FDG microPET and small-animal MRI
Douglas J Rowland1, Joel R Garbow, Richard Laforest
1Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA. rowlandd@wustl.edu
Abstract:
This paper describes a voxel-based method for coregistering microPET [(18)F]FDG emission images and MRI data without the need for fiducial markers. [(18)F]FDG has a well-characterized biodistribution in normal mice and thus may be useful for image registration. Female BALB/c mice were implanted with EMT-6 mouse mammary carcinoma 1 week prior to imaging. Three imaging sessions were performed in which a [(18)F]FDG microPET-R4 emission scan was taken followed by small-animal MRI with and without Gd-based contrast agent. MicroPET and MR images were registered using a voxel-based algorithm that computes rigid-body image transformations based on the alignment of intensity gradients. Registration accuracy was assessed on the basis of dual-modality external fiducial line sources incorporated into the mouse bed. The root mean square (rms) registration errors were 0.74 mm translation and 1.44 degrees rotation without contrast and 0.72 mm translation and 0.89 degrees rotation with contrast. Generally, good registration was evident upon inspection of fused microPET/MR images. Accurate automated, voxel-based microPET-MR image coregistration, utilizing image intensity gradients, is feasible. Our technique requires no manual identification of image features and makes no use of surgically implanted or external fiducial markers or stereotactic apparatus.
Insights
This study presents a novel voxel-based method for accurately aligning microPET ([(18)F]FDG) and MRI scans in mice without markers. This automated technique enhances multimodal imaging for research applications.
Area of Science:
- Biomedical Imaging
- Medical Physics
- Radiochemistry
Background:
- Accurate image registration is crucial for multimodal imaging in preclinical research.
- Existing methods often rely on fiducial markers, which can be invasive or introduce inaccuracies.
- Fluorine-18 fluorodeoxyglucose ([(18)F]FDG) PET imaging offers a valuable functional imaging modality.
Purpose of the Study:
- To develop and validate a marker-free, voxel-based method for coregistering microPET ([(18)F]FDG) and MRI data.
- To assess the accuracy of the registration method with and without contrast agents.
- To demonstrate the feasibility of automated image fusion for preclinical studies.
Main Methods:
- A voxel-based algorithm was employed to align microPET and MRI images by matching intensity gradients.
- The method was tested on female BALB/c mice bearing EMT-6 mammary carcinoma.
- Registration accuracy was evaluated using external fiducial line sources, calculating root mean square (rms) errors.
Main Results:
- The voxel-based registration achieved high accuracy, with rms errors of 0.74 mm translation and 1.44 degrees rotation without contrast.
- With Gd-based contrast agent, registration accuracy improved to 0.72 mm translation and 0.89 degrees rotation.
- Visual inspection of fused microPET/MR images confirmed good registration quality.
Conclusions:
- Automated, voxel-based coregistration of microPET ([(18)F]FDG) and MRI is feasible and accurate.
- The developed technique eliminates the need for manual feature identification, fiducial markers, or stereotactic equipment.
- This marker-free approach simplifies and improves the reliability of multimodal image analysis in preclinical research.
![Visualization and Quantification of Brown and Beige Adipose Tissues in Mice using [18F]FDG Micro-PET/MR Imaging](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F62460.jpg&w=3840&q=50)
