Related Experiment Video
Updated: Jul 5, 2026
In vivo Macrophage Imaging Using MR Targeted Contrast Agent for Longitudinal Evaluation of Septic Arthritis
Published on: October 20, 2013
Macrophage activity in infected areas of an experimental vertebral osteomyelitis model: USPIO-enhanced MR
Guillaume Bierry1, François Jehl, Nelly Boehm
1Department of Radiology 2, University Hospital of Strasbourg, Strasbourg, France. guillaume.bierry@chru-strasbourg.fr
Purpose:
To prospectively evaluate ultrasmall superparamagnetic iron oxide (USPIO) magnetic resonance (MR) imaging for the depiction of macrophages in infected areas of an experimental rabbit vertebral osteomyelitis model.
Materials And Methods:
Lumbar vertebral osteomyelitis was induced in 10 rabbits with intradiscal injection of bacteria in a vertebral disk (test level) versus saline injection in another disk (control level). After a mean interval of 12 days, rabbits were imaged prior to and 24 hours after administration of USPIO. The MR imaging protocol included T1-weighted spin-echo, T2-weighted fast spin-echo, and T2*-weighted gradient-echo sequences. MR findings were compared with histologic findings (macrophage immunostaining and Perls Prussian blue staining). A Wilcoxon signed rank test was used to compare signal-to-noise ratio (SNR) results before and after USPIO administration.
Results:
T1-weighted MR images of infected vertebral test levels obtained 24 hours after USPIO administration showed a significant increase in SNR (P = .005), whereas T2- and T2*-weighted images showed no significant changes in SNR (P = .14 and P = .87, respectively). Histologic examination results of infected areas demonstrated complete replacement of hematopoietic bone marrow by macrophage infiltration. Perls Prussian blue staining showed that some macrophages were iron loaded. T1- (P = .02), T2- (P = .04), and T2*-weighted (P = .04) images of control vertebrae showed a significant decrease in SNR. Histologic examination results confirmed the persistence of normal hematopoietic bone marrow without macrophage infiltration, which was reflected by more intensive Perls Prussian blue staining compared with that in infected areas.
Conclusion:
MR imaging can depict USPIO-loaded macrophage infiltration present in infected areas in an experimental rabbit model of vertebral osteomyelitis.
Insights
Ultrasmall superparamagnetic iron oxide (USPIO) magnetic resonance imaging effectively depicts macrophage infiltration in infected bone marrow. This technique shows promise for diagnosing vertebral osteomyelitis in experimental rabbit models.
Area of Science:
- Biomedical Imaging
- Osteomyelitis Research
- Macrophage Biology
Background:
- Vertebral osteomyelitis is a challenging bone infection.
- Accurate detection of inflammatory infiltrates, like macrophages, is crucial for diagnosis and treatment.
- Current imaging modalities may have limitations in visualizing cellular-level inflammation.
Purpose of the Study:
- To prospectively evaluate ultrasmall superparamagnetic iron oxide (USPIO) magnetic resonance (MR) imaging.
- To assess USPIO's capability in depicting macrophages within infected areas.
- To utilize an experimental rabbit model of vertebral osteomyelitis.
Main Methods:
- Induction of lumbar vertebral osteomyelitis in rabbits via bacterial injection.
- MR imaging performed before and after USPIO administration using T1, T2, and T2*-weighted sequences.
- Comparison of MR findings with histologic analysis, including macrophage immunostaining and Perls Prussian blue staining.
Main Results:
- T1-weighted MR images showed a significant increase in signal-to-noise ratio (SNR) in infected vertebral levels post-USPIO (P = .005).
- Histology confirmed macrophage infiltration replacing bone marrow in infected areas, with some macrophages iron-loaded.
- Control vertebrae showed decreased SNR, consistent with normal hematopoietic bone marrow and no significant macrophage infiltration.
Conclusions:
- MR imaging with USPIO can successfully depict USPIO-loaded macrophage infiltration in infected vertebral osteomyelitis.
- This imaging approach holds potential for non-invasively visualizing inflammatory cellular responses in bone infections.
- The study demonstrates the utility of USPIO-enhanced MR imaging in an experimental model of vertebral osteomyelitis.
More Related Videos
18:40Combined In vivo Optical and µCT Imaging to Monitor Infection, Inflammation, and Bone Anatomy in an Orthopaedic Implant Infection in Mice
Published on: October 16, 2014
07:33In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur
Published on: November 14, 2017